Post on 03-Mar-2018
transcript
The Hydrogen Bridge
Interactions without borders
Gautam R DesirajuSchool of Chemistry
University of HyderabadHyderabad 500 046 India
Pisa 6 September 2005
Under certain conditions an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond between them
Hydrogen bond XndashHhellipAPauling definition (1939)
A hydrogen bond is said to exist when (1) there is evidence of a bond and (2) there is evidencethat this bond sterically involves a hydrogen atomalready bonded to another atom
Hydrogen bond XndashHhellipAPimentelndashMcClellan definition (1960)
Hydrogen bond XndashHhellipASteinerndashSaenger definition (1993)
Any cohesive interaction where H carries a positive charge and A a negative charge (partial or full) and the charge on H is more positive than on X
Hydrogen bond
OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO
OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO
OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ
How to assess hydrogen bonds
bull Energybull Spectroscopybull Geometrybull Structurebull Function
A complex interaction
lt 001001 to 005005 to 02∆(XndashH) Aring
VariableDistinctivePronouncedEffect on crystal packing
30-80~100100Shorter than van der Waals
20 to 3015 to 2212 to15HhellipA Aring
lt55-25gt25IR νs
lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)
CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash
WeakStrongVery strong
The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low
electronegativity (1999)
DesirajundashSteiner definition
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Under certain conditions an atom of hydrogen is attracted by rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond between them
Hydrogen bond XndashHhellipAPauling definition (1939)
A hydrogen bond is said to exist when (1) there is evidence of a bond and (2) there is evidencethat this bond sterically involves a hydrogen atomalready bonded to another atom
Hydrogen bond XndashHhellipAPimentelndashMcClellan definition (1960)
Hydrogen bond XndashHhellipASteinerndashSaenger definition (1993)
Any cohesive interaction where H carries a positive charge and A a negative charge (partial or full) and the charge on H is more positive than on X
Hydrogen bond
OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO
OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO
OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ
How to assess hydrogen bonds
bull Energybull Spectroscopybull Geometrybull Structurebull Function
A complex interaction
lt 001001 to 005005 to 02∆(XndashH) Aring
VariableDistinctivePronouncedEffect on crystal packing
30-80~100100Shorter than van der Waals
20 to 3015 to 2212 to15HhellipA Aring
lt55-25gt25IR νs
lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)
CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash
WeakStrongVery strong
The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low
electronegativity (1999)
DesirajundashSteiner definition
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
A hydrogen bond is said to exist when (1) there is evidence of a bond and (2) there is evidencethat this bond sterically involves a hydrogen atomalready bonded to another atom
Hydrogen bond XndashHhellipAPimentelndashMcClellan definition (1960)
Hydrogen bond XndashHhellipASteinerndashSaenger definition (1993)
Any cohesive interaction where H carries a positive charge and A a negative charge (partial or full) and the charge on H is more positive than on X
Hydrogen bond
OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO
OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO
OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ
How to assess hydrogen bonds
bull Energybull Spectroscopybull Geometrybull Structurebull Function
A complex interaction
lt 001001 to 005005 to 02∆(XndashH) Aring
VariableDistinctivePronouncedEffect on crystal packing
30-80~100100Shorter than van der Waals
20 to 3015 to 2212 to15HhellipA Aring
lt55-25gt25IR νs
lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)
CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash
WeakStrongVery strong
The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low
electronegativity (1999)
DesirajundashSteiner definition
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Hydrogen bond XndashHhellipASteinerndashSaenger definition (1993)
Any cohesive interaction where H carries a positive charge and A a negative charge (partial or full) and the charge on H is more positive than on X
Hydrogen bond
OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO
OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO
OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ
How to assess hydrogen bonds
bull Energybull Spectroscopybull Geometrybull Structurebull Function
A complex interaction
lt 001001 to 005005 to 02∆(XndashH) Aring
VariableDistinctivePronouncedEffect on crystal packing
30-80~100100Shorter than van der Waals
20 to 3015 to 2212 to15HhellipA Aring
lt55-25gt25IR νs
lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)
CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash
WeakStrongVery strong
The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low
electronegativity (1999)
DesirajundashSteiner definition
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Hydrogen bond
OndashHmiddotmiddotmiddotO(-) OndashHmiddotmiddotmiddotO NndashHmiddotmiddotmiddotO
OndashHmiddotmiddotmiddotπ NndashHmiddotmiddotmiddotπ CndashHmiddotmiddotmiddotO
OsndashHmiddotmiddotmiddotO CndashHmiddotmiddotmiddotNi CndashHmiddotmiddotmiddotπ
How to assess hydrogen bonds
bull Energybull Spectroscopybull Geometrybull Structurebull Function
A complex interaction
lt 001001 to 005005 to 02∆(XndashH) Aring
VariableDistinctivePronouncedEffect on crystal packing
30-80~100100Shorter than van der Waals
20 to 3015 to 2212 to15HhellipA Aring
lt55-25gt25IR νs
lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)
CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash
WeakStrongVery strong
The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low
electronegativity (1999)
DesirajundashSteiner definition
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
How to assess hydrogen bonds
bull Energybull Spectroscopybull Geometrybull Structurebull Function
A complex interaction
lt 001001 to 005005 to 02∆(XndashH) Aring
VariableDistinctivePronouncedEffect on crystal packing
30-80~100100Shorter than van der Waals
20 to 3015 to 2212 to15HhellipA Aring
lt55-25gt25IR νs
lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)
CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash
WeakStrongVery strong
The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low
electronegativity (1999)
DesirajundashSteiner definition
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
lt 001001 to 005005 to 02∆(XndashH) Aring
VariableDistinctivePronouncedEffect on crystal packing
30-80~100100Shorter than van der Waals
20 to 3015 to 2212 to15HhellipA Aring
lt55-25gt25IR νs
lt ndash 4ndash 4 to ndash 15ndash15 to ndash40Energy (kcalmol)
CndashHhellipONndashHhellipO=C[FndashHhellipF]ndash
WeakStrongVery strong
The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low
electronegativity (1999)
DesirajundashSteiner definition
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
The weak hydrogen bond isan interaction XndashHA whereina hydrogen atom forms a bond between two structural moietiesX and A of which one or even both are of moderate to low
electronegativity (1999)
DesirajundashSteiner definition
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Cl3ndashnRnCndashHhellipO
G R Desiraju J Chem Soc Chem Comm 179 1989
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Angles XndashHhellipO
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
IR bathochromic shifts CndashHhellipO
G R Desiraju and B N Murty Chem Phys Lett 139 360 1987
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Thermal parameters
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Isostructurality
N
N
H
O
O
O
EtEt N
NO
HH
HH
H231
205
N
N
H
O
O
O
EtEt
NO
HH
HH HH
256
201
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Two molecules in the asymmetric unit (Zrsquo=2)
OO
HH
HH H
Me2NO
O
H
CH3
H
Me2N
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Fluorine
CmdashHhelliphelliphelliphellipFmdashCWeak donor Very weak acceptor
Electronegativity and Hardness
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
F FF
F
F F
F
F
FF
FF
F
F
F
F
FF
FF
F
CndashHmiddotmiddotmiddotFndashC Interactions in Fluorobenzenes
Thalladi Weiszlig et al JACS 120 8702 1998
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
CndashHmiddotmiddotmiddotFndashC Hydrogen Bonds
All C H F compounds Fluorobenzenes
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Polymerization catalyst
Zr+ H
H
FFF
Stereoselective polymerisationChan et al
Angew Chem Int Ed42 1628 2003
Boron adductsLancaster et al Chem Comm
2148 2003
Decrease of β-H transferT Fujita et al
JACS 124 3327 2002JACS 125 4293 2003
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Weak and reversible CndashHmiddotmiddotmiddotFndashC Hydrogen Bridge Applications Molecular recognition
Binding in thrombin
Diederich et al
Angew Chem Int Ed
42 2507 2003
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Electrostatics
Charge transfer (covalency)
Dispersionrepulsion (van der Waals)
Polarisation
A composite interaction
Hydrogen bridge (Wasserstoffbruumlcke)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
[HF2]-
Electrostatic limit(15 kcalmol)
van der Waals limit(025 kcalmol)
weak hydrogen bonds
Covalent limit (40 kcalmol)
very strong hydrogen bonds
strong hydrogen bonds
very weakinteractions
X H X
PhsdotsdotsdotPh
NH2
NH2
O O PO(OH)2H
NHsdotsdotsdotπNHsdotsdotsdotCo
R R
OOH
OCl5
N CH3H
NHsdotsdotsdotNH
OsHsdotsdotsdotOequivC
OHsdotsdotsdotOHCequivCHsdotsdotsdotOH
CHsdotsdotsdotClminusNHsdotsdotsdotS
Cl3CHsdotsdotsdotO=CMe2
CHsdotsdotsdotClCC=CHsdotsdotsdotO
OHsdotsdotsdotπ
CHsdotsdotsdotFCCHsdotsdotsdotS
CequivCHsdotsdotsdotπ
NH4+sdotsdotsdotFminus
NH4+RCOOminus
NH4+sdotsdotsdotClminus
NMe4+sdotsdotsdotXminus
CH4sdotsdotsdotπ
CH4sdotsdotsdotAr
OHsdotsdotsdotO=C
NH4+sdotsdotsdotπ
(NO2)3CHsdotsdotsdotO
NHsdotsdotsdotO=C
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Hydrogen bond (bridge)
DmdashHhelliphellipAA complex interaction that involves several atoms
A composite interaction that spans wide ranges of geometry and energy
Great chemical variations among the donor DmdashH and acceptor A groups
However all hydrogen bonds (bridges) have several features in common notably their effect on crystal structure and packing
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
The above discussion shows that hydrogen bonds of differing strengths have broadly similar if graded effects in the building up of crystals from molecules Indeed it is at the functional level rather than at a geometrical energetic or spectroscopic level that all hydrogen bonds are similar and it is little surprise that it is in the fields of crystal engineering and supramolecular chemistry that the hydrogen bond is most clearly identified as an interaction type without internal borders
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Hydrogen bridgeThe master-key of molecular recognition
StrengthDirectionalityWeaknessFlexibility
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
CndashHhellipO Hydrogen Bonds in the Nuclear Receptor RARγγγγ
Klaholz and Moras Structure 10 1197-1204 2002
Specificity
Reversibility
Affinity
Hydrophobicity
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)
Paulingrsquos definition
Under certain conditions an atom of hydrogen is attractedby rather strong forces to two atoms instead of only one so that it may be considered to be acting as a bond betweenthem
Modern definition
Under certain conditions an atom of hydrogen is attractedto two atoms instead of only one so that it may be considered to be acting as a bridge between them
Bonds and bridges
Students post-docsThomas SteinerJagarlapudi SarmaUniversity of HyderabadDST CSIR DRDOIUPAC (Arunan Klein)