Concepts Supramolecularchemistry

Supramolecular Chemistry

http://homepage.univie.ac.at/jeanluc.mieusset/teaching.html

Supramolecular Chemistry 1 - Concepts.pdf

Supramolecular Chemistry 2 - Cation binding.pdf

Supramolecular Chemistry 3 - Binding of anions.pdf Supramolecular Chemistry 4 - Neutral molecules.pdf

Supramolecular Chemistry 5 - Methods.pdf

Supramolecular Chemistry 6 - Self-Assembly.pdf Supramolecular Chemistry 7 - Artificial enzyms.pdf

Supramolecular Chemistry 8 - Molecular Devices.pdf

Supramolecular Chemistry 9 - Molecular Machines.pdf Supramolecular Chemistry 10 - New.pdf

Supramolecular Chemistry

Steed, J. W.; Atwood, J. L. Supramolecular Chemistry,Wiley 2000 $ 40,-

Balzani, V.; Venturi, M.; Credi, A.Molecular Devices and MachinesWiley VCH 2003

Schneider, H.-J.; Yatsimirski, A. Principles and Methods in Supramolecular ChemistryWiley 2000 £ 39,95

Comprehensive Supramolecular Chemistry, Vol. 1-10; Lehn, J.-M., Series editor, Pergamon/Elsevier Oxford etc, 1996 $ 425 per volume

Encyclopedia of Supramolecular Chemistryedited by Jerry L. Atwood and Jonathan W. SteedDekker, 2004 • 1,500 pages • $489.00

What is Supramolecular Chemistry?

MULTIDISCIPLINARY FIELD

NATURE (biological systems) - inspiration

ORGANIC and INORGANIC CHEMISTRY – building blocks(supramolecular synthons)

PHYSICAL CHEMISTRY – methods to study and understand their properties


The ultimate supramolecular material?

Held together by many specific hydrogen bonds, π-π stacking, etc.

Encodes gigabytes of data Can Self-Replicate

Built-in Error Correction

Information Storage Is the basis of life


Tobacco Mosaic Virus (TMV)


Actin-Myosin Complex


Kinesin Crawling Along a Microtubule


MOLECULAR CHEMISTRY – covalent bonds formation

SUPRAMOLECULAR CHEMISTRY – “non-covalent bond” format ion


J. M. Lehn:„Supramolecular chemistry is the chemistry of the i ntermolecular bond, covering the structures and functions of the e ntities formed by the association of two or more chemical species“

F. Vögtle:„In contrast to molecular chemistry, which is predo minantly basedupon the covalent bonding of atoms, supramolecular c hemistry is based upon intermolecular interactions, i.e. on the association of two or more building blocks, which are held together by intermolecular bond”



But also:

Molecular Devices Supramolecular Photochemistry Electronic Switches Dendrimers


Top-Down (current technology). Continued reduction in size of bulk semiconductor d evices optical, ultra-violet, ion-beam, electron-beam lith ography

Bottom-Up (molecular scale electronics). Design of molecules with specific electronic functi on Design of molecules for self-assembly into supramol ecular structures Connecting molecules to the macroscopic world Man-made synthesis (e.g. carbon nanotubes)


1-50 nm 1-500 nm

SupramolecularAggregates

Nanoelectronicsnanobiology

Development - History

Development - History

Classification of Host-Guest Compounds


Spherand


Corpora non agunt nisi fixata

Receptors and the Lock and Key Analogy

The Chelate and Macrocyclic Effects



Less entropically favorable

Stabilization offered by the chelate effect

Preorganization and Complementarity

Preorganization and Complementarity

Nature of Supramolecular Interactions

Covalent bond energies:

C-O bond 340kJ / mol 1.43ÅC-C bond 360kJ / mol 1.53Å

C-H bond 430kJ / mol 1.11Å

C=C bond 600kJ / mol 1.33ÅC=O bond 690kJ / mol 1.21Å

Compared to most non-covalent interactions these are:

• Very high energies

• Very short distances • Highly dependant on orientation


Driving Forces for the Formation of Supramolecular Structures

hydrophobic interaction <40 kJ/mol electrostatic interaction ~20 kJ/mol

hydrogen bond interaction 12-30 kJ/mol

van der Waals interaction 0.4-4 kJ/mol

cation –π interaction 5-80 kJ/mol

π−π stacking 0-50 kJ/mol

The total inter-molecular force acting between two molecules is the sum of all the forces they exert on each other.



Ion - Ion Interactions

Can be a very strong bond - even stronger then covalent bonds in some cases.

Can be an attractive or a repulsive force.

Non-directional force

Long range (1/r)

Highly dependant on the dielectric constant of the medium


IonIon––IonIon InteractionsInteractions

Energy = (k * z1 * z2 * e2) / (ε ∗ r12)

k = 1 / 4πεo= Coulomb constant = 9*109Nm2/C2

e = elementary charge = 1.6*10-19C

ε = dielectric constant

r12 = meters between the objects

The energy of an ion-ion interaction only falls of at a rate proportional to 1 / r. Therefore these are very long range forces.


IonIon––IonIon InteractionsInteractions

1 nm in water?

1 nm in Chloroform ?

Energy = (k * z1 * z2 * e2) / (ε ∗ r12)

= 9*109 * 1 * -1 * (1.6*10-19)2 / 78.5 * 1 * 10-9

= -2.3 * 10 -28 / 0.8 * 10 -7

= -29.4 * 10-22 J= -1.77 kJ / mole (-0.42 kcal / mole)

= 9*109 * 1 * -1 * (1.6*10-19)2 / 4.8 * 1 * 10-9

= -2.3 * 10 -28 / 4.8 * 10-9

= -4.79 * 10-20 J= -28.8 kJ / mole (-6.89 kcal / mole) -> 8% of a C-C bond



Energy = -(k * Q * u * cosθ / e * r2) If θ = zero= -k * Q * u / e * r2

= -9*109 * 1.6*10-19 * 2.9 * 3.336 *10-30 / e * r2

= -1.39 * 10-38 / 4.8 * (10-9)2

= -2.9 * 10-21 J= -1.75kJ / mole

Example: Acetone pointing directly at Na ion (θ = zero) at a distance of 1nm (in chloroform)

IonIon--Dipole InteractionDipole Interaction

u = q * l (dipole moment)l = length of the dipoleq = partial charge on dipoler = distance from charge to center of dipoleQ = charge on ion


IonIon--Dipole InteractionDipole Interaction

Directional forces

Can be attractive or repulsive

Medium range (1/r2)

Significantly weaker then ion-ion interactions


Nature of Supramolecular Interactions :Hydrogen Bonding




Van der Waals radius of H: 1.1Å, O 1.5Å. Therefore closest approach should be 2.6Å.

Actual separation is about 1Å less!Distance of 1.76Å.

Intermediate between vdw distance and typical O-H covalent bond of 0.96Å.

O H OR

RH

O H OR

RH




Nature of Supramolecular Interactions :Halogen Bonding

Halogen atoms iodine, bromine, chlorine and even fl uorine can function as Lewis acids and engage in electron dono r-acceptor interactions with atoms with lone pairs such as nit rogen, oxygen, phosphorus and sulfur.

BI…X- Halogen bonding may involve dihalogenes X2 and X-Y as well as

organic halides

The strength of the donor-acceptor interaction depe nds on the polarizability of the halogen atom, decreases in the order:

I > Br > Cl (> F)

Nature of Supramolecular Interactions :Halogen Bonding

DMSO to haloarene halogen bonding geometry:

“head on“ to C-X, Γ~ 158(13)° (Cl), 162(12)°(Br), and ~165(8)°(I);

“side on“ to S=O, Ω: 125-135°.

Increase of polarity of the both C-X and S=O bond increases the strength of interaction:

Nature of Supramolecular Interactions :The Cation – ππππ Interaction

Nature of Supramolecular Interactions :π π π π – ππππ Stacking



Nature of Supramolecular Interactions :π π π π – ππππ Interactions

Chem. Rev. 2000,100, 4145-4185.

Nature of Supramolecular Interactions :Charge-Transfer Complex

Nature of Supramolecular Interactions :Van der Waals Forces

Strength of interaction is essentially a function of the surface area of contact. The larger the surface area the stronger the interaction will be.

Regardless of other interactions found within a complex there will almost always be a contribution from vdw.

This is what drives molecules to eliminate spaces or vacuums and makes it difficult to engineer porous or hollow structures and gives rise to the phrase “Nature abhors a vacuum”.

Nature of Supramolecular Interactions :Van der Waals Forces

Nature of Supramolecular Interactions :CLOSE PACKING IN THE SOLID STATE

Conformers allowing maximum intermolecular interactions, even very weak (which do not play a r ole in solution)

„Empty“ space: crystal pores and channels -> inclusi on crystals

TETRIS analogy

Nature of Supramolecular Interactions :Hydrophobic Effects

Nature of Supramolecular Interactions :Hydrophobic Effects

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Concepts Supramolecularchemistry

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