Construction of Near-Infrared
Chiroptical Polymers Based on
Electrochromic viologens
Peking UniversityDeng Jian
2007.07.18
Outline
Background
Hypothesis
Theories
Experimentals and Properties
Near-Infrared Chiroptical Properties
Summaries and Plans
Background
As we peer into the next century, we foresee developments in optics that will change our lives in ways that today we can hardly even contemplate.
The role of optics in research, which already cuts across nearly all fields of science and technology, will be limited only by our imagination.
Harnessing Light by National Research Council of US in 1998
To fully explore the utility of light, new theory must be developed for a better understanding of the nature and the behavior of light when interacting with matters; and new materials and devices must be developed for a better control (e.g. in terms of methodology, extent and efficiency) of light.
Challenges:
Chiral PhotonicsChiral Photonics: Studies making use of the unique chiroptical properties, such as polarization and circular dichroism, of a chiral material as well as of other optical phenomena arose from the unique chiral asymmetric structure for various photonics applications such as lasing, light waveguiding, sensoring, and information storage etc.
• Display
• Chiroptical switch
• Chiral fluorescent sensor
• Chiral lasing
• Chiral waveguide
• Nonlinear optics
• Optical storage media
Chiral Recognition
1-D photonic Ordering
Circular Birefringence and Dichroism
Helical waveguide usable for selective filtering, scattering and
coupling
Chiroptical switch triggered by light
Feringa, Ben L. et al.Chiral photonics, Inc.
Potential uses:
NIR Chiroptical Polymers
• Polarization control (in particular for integrated systems)
• Sensoring and information storage
• EO Modulator via Polarization
Z. Y. Wang, E. K. Todd, X. S. Meng, J. P. Gao, J. Am. Chem. Soc. 2005, 127, 11552.
Phase vs polarization
ChiralityMolecular Chirality Chirality in NatureSupramolecular Chirality
Symmetry
Chirality of a molecule is a symmetry propertiesAsymmetric :no any symmetry element (C1)
Dissymmetric: only axes of rotation (Cn and Dn)
(
(
S (n
i
σ
πn
镜面) 在一个平面上反映
(对称中心) 通过一个中心倒反
C对称轴) 围绕一个轴旋转2 / n弧度
旋转反映轴) 于该轴的平面上反映
Light and Chiroptical Properties
Electromagnetic waves
Optical rotation
Circular Dichroism
α , θ (degree)d=cell length (cm) d’=cell length (dm)c=concentration (M) c’=concentration (g/cm3)n=refractive index ε=absorption coefficient (M-1cm-1)λ=wavelength of incident light (nm)
100[ ]
dc
αψ =180( )l rn n dαλ−= [ ]
' 'd c
αα =
Polarimeter and Circular dichroism Spectrometer
10
4500[ ] log 10log r
el
I
LC Iθ
π
=
1( )
2a r lI I I= +
r lS I I= −
10
124500
[ ] log 10log1
2
ae
a
S
ISLCI
θπ
+ = −
10
4500[ ] log 10 logs
ea
Ee
LC Eθ
π
=
10log4500[ ] log 10 s
ea
E G e
LC E Gθ
π =
100[ ] 3300( )l rdc
θθ ε ε= = −
Kramers-Kronig relation
Inter-relationship between ORD and CD Curves
Rosenfeld’s equation:
Dependence of ORD and CD on wavelength
λ1 λ2
2 2
2 2
296[ ( )]
3i i
i i
n RN
hcλ λπψ λ
λ λ+=
−∑
JACS 1998,120, 6185
Dependence of ORD and CD on chromophore interaction
Kirkwood’s Coupled Oscillator Model
NoncoplanarNon-perpendicularProper distance
Hypothesis
Appropriate introduction of electro/photochromic chromophores into a suitable chiral structure should lead to Electrically or Optically controllable chiroptical properties, which should find wide applications in areas where polarization control is of concern.
N N+e +e
N N
OX RED2
N N
RED1
260 nm 394, 605 nm 394 nm
Structural Design I:
605394260
Structural Design II and Contents of Researches
(R)-BEBPP (R)-BEBPB
(R)-CBEBPB
O
O
N
N
N
N
PF64 xO
O
N
N
N
N
PF64 x
O
O
N
N
N
N
PF64 x
Axially Dissymmetric Compounds:
Synthetic Approach:
OH
OH
O
O
OH
OH
O
O
O
O
S
S Me
Me
O
OO
O
O
O
Br
Br
O
O
N
N
N
N
HOCl
K2CO3
DMF, 110 oC
70%
MeSO2Cl, NEt3, DMAP
CH2Cl292.5%
LiBr
DMSO
50%
N N
(+)-, (R)-BINOL
(+)-, (R)-BEBP
PF62 x
Br
, DMF (110 oC)1)
2) KPF6, 85%
O
O
N
N
N
N
(+)-, (R)-BEBPB
PF64 x
(+)-, (R)-BE (+)-, (R)-BES
(+)-, (R)-BEB
O
O
N
N
N
N(+)-, (R)-BEBP
PF62 x
2) KPF6, 11%
Br
Br
+1) MeCN, 110 oC O
O
N
N
N
N(+)-, (R)-CBEBP
PF64 x
O
O
N
N
N
N
PF64 x
4 mg / 1 mL 0.1 M Bu4NClO4 DMF- 0.7 V
300 350 400 450 500 550 600 650 700 750 800 850
0.5
1.0
1.5
2.0
2.5
3.0
3.5
Ab
s / %
Wavelength / nm
0 min 3 min 6 min 7 min 10 min
200 250 300 350 400
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Ab
sorb
ance
Wavelength / nm
BPP BEBP BEBPB CBEBPB
0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2
-2
0
2
4
6
Cu
rren
t/1e
-5 A
Potential/V
300 400 500 600 700 800-15
-10
-5
0
5
10 (R)-BEBPB-CD (R)-BEBPB-ECCD
Elli
pti
city
/ m
deg
Wavelength / nm
O
O
N
N
N
N
PF64 x
200 300 400 500 600 700 800
-120
-90
-60
-30
0
30
60 (R)-CBEBPB (R)-CBEBPB Reduced
CD
/md
eg
Wavelength/nm
0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
Cu
rren
t/1e
-5 A
Potential/V
300 400 500 600 700 8000.0
0.5
1.0
1.5
2.0 0S 17S 27S 57S
Ab
s
Wavelength/nm
4 mg / 1 mL 0.1 M Bu4NClO4 DMF- 0.7 V
400 600 800-60
-50
-40
-30
-20
-10
0
10
20
30
40 6 7 8 9 10 11 12 131 14 15
CD
/md
eg
Wavelength/nm
300 400 500 600 700 800
-10
-5
0
5
10 2 3 4
CD
/md
eg
Wavelength/nm
Demonstration of electrochemical Switching of CD signals of (R)-CBEBPB in 0.1 M Bu4NClO4/DMF. (a) first reduction at -0.5 V for 5 s; (b) recovered tetracation by bubbling slowly nitrogen into the solution; (c) second reduction at -0.7 V for 1 min.
Demonstration of electrochemical Switching of CD signals of (R)-CBEBPBby tin. (a) first reduction by tin bublingnitrogen; (b) recovered tetracation by bubbling slowly air into the solution; Repeat (a) and (b) five times.
Near-infrared chiroptical properties
2
1
39 ( )2.297 10R d
λ
λ
ε λ λλ
− ∆= × ∫2
2 2
9147[ ] i i
i i
R
Mλλα
λ λ = −
∑
3 1 1
40 2 2
[ ] : deg
:
: 10
:
i
i
specific rotation in cm g dm
M molecular weight
R rotational strength of the ith excitation in esu cm
incident wavelength in nm
wavelength of the ith excitation
λα
λ
λ
− − −
−
⋅
ORD caculated from experimental data
J.Phys.Chem. A, 2003, 107, 2524J.Am.Chem.Soc., 2004,126, 7514
(a)
(b)
400 500 600 700 800 900 1000 1100
-150
-100
-50
0
ORD Caculated from Experimental Rotational Strength ORD Scaled Experimental Data
[a]
Wavelength / nm
R-BEBPB
Rotational strength calculated from this diagram.via formula (a).
ORD calculated via formula (b).
Exp Cal1 Cal2546 -43.5 -16.2 -49.7588 -39.5 -12.9 -39.4
λi Ri223 1.086775780E-38233 -1.064117390E-38257 1.558239296E-39285 -1.301346498E-39
R-CBEBPB
400 500 600 700 800 900 1000 1100
0
100
200
300
400
500
600
ORD Calculated from Experimental Rotational Strength ORD Scaled Experimental Data
[a]
Wavelength / nm
R-CBEBPB Reduced
1000 1500 2000 2500 3000 3500 4000 4500 5000
-125
-100
-75
-50
-25
0
[a]
Wavelength / nm
1000 1500 2000 2500 3000 3500 4000 4500 5000
-250
-225
-200
-175
-150
-125
-100
-75
-50
-25
0
[a]
Wavelength / nm
O
OH
O
HO
BrBr
+ BHO
HOB
OH
OH
C8H17 C8H17
Pd catalyst
O
OH
O
HO
C8H17
C8H17
O
OH
O
HO
C8H17
C8H17
O
OH
O
HO
C8H17
C8H17
O
OH
O
HO
C8H17
C8H17
O
OH
O
HO
1. [α]D23.9 = -224.5o (4.0 mg/10 mL DMF), Mn:5295
2. [α]D23.7 = -399 o (4.0 mg/10 mL DMF), Mn:15477, PD:1.42
-5 0 5 10 15 20 25 30 35
-10
0
10
20
30
40
Polymer Based on Model Compounds
O
OH
O
HO
C8H17
C8H17
O
OH
O
HO
C8H17
C8H17
O
OH
O
HO
C8H17
C8H17
O
OH
O
HO
C8H17
C8H17
O
OH
O
HO
TsCl/NEt3 KI/DMF 75oC
O
N
O
N
C8H17
C8H17
O
N
O
N
C8H17
C8H17
O
N
O
N
C8H17
C8H17
O
N
O
N
C8H17
C8H17
O
N
O
N
NNN NN N
NNN N
1. [α]D23.9 = -100.0o (4.0 mg/10 mL DMF), Mn:6695
Grafting: 50%2. [α]D
23.9 = -?, Mn:? Grafting: 50%
200 300 400 500 600 700 800-0.4
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4A
bs
Wavelength / nm
DJ-E-55 DJ-E-71
300 400 500 600 700 800
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5 4 3 2 1
Ab
s
Wavelength/nm
200 300 400 500 600 700 800-4
-3
-2
-1
0
1
2
md
eg
Wavelength / nm
DJ-E-55 DJ-E-71
200 300 400 500 600 700 800
-25
-20
-15
-10
-5
0
5
10
15
20
md
eg
Wavelength/nm
010
110
210
0 2 4 6 8 10 12 14 16 18
6.5
0.0
-6.5
Co
unts
Re
sidu
als Time/ns
Decay2IR2Decay2F2Decay2F2
Fit Resultsτ1 7.30nsτ2 0.70nsχ2 1.268
010
110
210
310
0 2 4 6 8 10 12 14 16 18
3.8
0.0
-3.8
Co
unts
Re
sidu
als Time/ns
Decay3IR3Decay3F2Decay3F2
Fit Resultsτ1 11.65nτ2 1.12nsχ2 1.533
300 400 500 600 700
0
50
100
150
200
250
300
350
Flu
ore
scen
ce In
tesi
ty
Wavelength / nm
270 290 300 350 340 360 370 380 390 400 410
200 300 400 500 600 700
-2
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
Flu
ore
scen
ce In
tesi
ty
Wavelength / nm
240 270 290 300 340 350 360 370 380 390 400
0 100 200 300 400 500 600
0.6
0.8
1.0
wei
ght
loss
T (? )
DJ-E-55
Helical polymers:
Br
*
N
*N
2(Br -)
H
n
* Br
H
n
N
*
N
2(Br -)
H
m
* Br
H
n
N
N
2(Br -)
N
N
2(Br -)
Alkynyl Monomer
Br
HN
O
H2N
NH
O
O
NH
O
O
NH
NH
O
ONH
O
NH
O
O
DJ-B-9
DJ-B-21 DJ-B-69
DJ-C-21
DJ-C-43(55)
NH
O
HN O
N
NBr
Br
N
N Br
NHO
Br
DJ-B-59 DJ-C-87
NH
O
NHO
Br
DJ-C-67
O
NH
HNO
O
SO OO
NH
HNO
O
SO O
Synthesis of achiral monomers
NNBr
OBr OH + H2N
DCC,DMAP,DMF
or,EDC.HCl,DMAP,DMF
NN
OOH
2(PF-
6)
NN
ONH
2(PF-
6)
NNBr
OBr NH
OHBr
O
+ H2NDCC,DMAP,CH2Cl2
or,EDC.HCl,DMAP,CH2Cl2NH
Br
O DCC: ~10%EDC: ~40%white solid1H NMR
NH
Br
O
+ N NBr
NNBr N
H
O
Br
white solid1H NMRresolvable: DMSO,H2Oindiscerptible: THF,PhMe,DMF
Synthesis of chiral monomers based on L-lactic acid
NNBr BrBr + NaO
O
O
NNBr OBr
O
O
DMF
HO
O
O+
OH
DEAD,PPh3,THFO O
O
NaOH HCl
O OH
O(HCHO)n,ZnCl2,HCl,EtOH
(HCHO)n,AlCl3,HCl,CH2Cl2
EDC.HCl,DMAP,MeCN
H2NO HN
O
O OH
O
Cl
white acerate crystall1H NMR[¦Á]D
28 =+13o
white acerate crystall1H NMR
含羧基的分子溴化后,不好分离。
溴化时,炔基会被加成。
应该先溴化,再引入手性单元和炔键。
HO
O
O+
OH
DEAD,PPh3,THFO O
O
NaOH HCl
O OH
ONBS,BPO,CCl4
NBS,AIBN,CHCl3
NaBrO3,NaHSO3,CH3COOC2H5
O OH
O
BrEDC.HCl,DMAP,MeCN
H2NO HN
O
NaBrO3,NaHSO3,CH3COOC2H5
alkynyl bond was added
can not be purified
white solid1H NMR
white acerate crystall1H NMR
Synthesis of chiral monomers based on L-alanine
BrBr
O
+NaOH
H2O/Et2O
no anticipant product
starting materialsH2N
OH
O
OHO
SOCl2
ClO
+ H2NOH
O
HNO
OH
O
NaBrO3,NaHSO3,CH3COOC2H5can not be purified
NaOH,H2O
HCl
HNO
OH
O
Br
O OH
NaBrO3, NaHSO3
CH3COOC2H5
O OH
Br
SOCl2
O Cl
Br
+ H2NOH
O
NaOH,H2Ofield is very low can not be purifiedHCl
OHN
Br
OH
O
对甲苯甲酰氯的活性比溴乙酰溴的活性低,可以在水中进行反应。
此反应尽管产率低但是可以发生,产率低的原因可能是苄溴和氨基发生了反应,自然就想到把氨基保护起来,所以就选择了 BOC-L-alanine 。
Synthesis of chiral monomers based on BOC-L-alanine
NHO
NHO
O
NHO
NH2 HCl
3M HCl bsaeNH
O
NH2
HO O
Br
SOCl2
Cl O
Br
NHO
NHO
O
NH
O
OH
O
O
DCC,DMAP
THF+
H2N
white solid1H NMR
NHO
NHO
O
NHO
NH2 HCl
3M HCl bsaeNH
O
NH2
NH
O
NHO
Br
+ N N
Br
CH3CH2OH
50 oC
NH
O
NHO
N
NBr
Br
yellow solid1H NMR[¦Á]D
27 =+33.5o (4 mg/10 mL DMF)resolvable: DMF,H2O
NHO
NH2
+
Cl O
Br
CHCl3/H2O
K2CO3
NH
O
NHO
Br
white acerate crystall1H NMR[¦Á]D
28 =+71.5o (4 mg/10 mL DMF)
[Rh(NBD)Cl}2 + Na(C6H5)4 Rh+(NBD)[B(C6H5)4]-
Rh Rh
Cl
Cl
[Rh(NBD)Cl]2
Rh Rh
Cl
Cl
[Rh(COD)Cl]2
B(C6H5)3
Rh
Rh+(NBD)[B(C6H5)-]
Rh+(BDN)[B(C6H5)4]-
Synthesis of Catalysts
Rh(COD)(tos)(H2O)
SO3H + Ag2OMeCN
r.t., 7hSO3Ag
2RhCl3 + 2C8H12 + 2EtOH + 2Na2CO3.10H2O
[Rh(COD)Cl]2 + 2CH3CHO + 4NaCl + CO2 + H2O
[Rh(COD)Cl]2 + SO3Agultrasonic, 3 min [Rh(COD)(tos)(H2O)
Polymerization of monomers
N
N Br
NHO
Br
[Rh(NBD)Cl]2,H2O
H
n
HN
yellow solid powderresolvable:H20,CH3OH,DMFwater phase GPC:1700
O
N
NBr
Br
NH
Br
O
Rh(NBD)[B(C6H5)4]
H
n
HN
+ N NBr
DMF,40 oC
O
Br
THF
yellow solid powderresolvable:H20,CH3OH,DMFwater phase GPC:1700
O HN
O
H
n
HN
O
Rh(NBD)[B(C6H5)4]
[Rh(NBD)Cl]2,CH3OH
[¦Á]D28 =+13o
(4 mg/10 mL DMF)[¦Á]D
28 = -76o
(4 mg/10 mL DMF)
O
NH
Br
O+ O HN
O
THF
Rh(NBD)[B(C6H5)]4[¦Á]D
28 = +14.5o
(4 mg/10 mL DMF)
Samples [M0]
[M0]/
[Cat]T/0C Time/h Solvent Yield/% M
n PD [a]D
DJ-C-85 0.08 100 50 12 THF 84 5896 1.25
DJ-C-79 0.08 100 r.t.
12 THF 68 6478 1.61 -86
THF 6338 1.51 -123
DJ-C-95 0.16 100 r.t 24 THF 85 9115 1.56 -182.5
DJ-D-7-2 0.1 100 r.t 20 THF 85 7792 1.69 -217.5
DJ-D-7-3 0.16 200 r.t.
20 THF 77 7882 1.9 -341.5
DJ-D-7-4 0.1 100 0 20 THF 83 7344 2.46 -479
NH
O
NHO
Br
Rh(NBD)[B(C6H5)]4
DT1
poor resolution of polymersmall optical rotationsmall molecular weight
NH
O
NHO
Br
THF
Rh(NBD)[B(C6H5)]4NH
OHN
OBr
H
n
N NBr
NH
O
HN O
N
NBr
Br
Rh(NBD)[B(C6H5)4],DMF
[Rh(NBD)Cl]2,H2O
?
NH
O
NH
O
O CH2Cl2
Rh(NBD)[B(C6H5)]4
Samples [M0]
[M0]/
[Cat]T/0C Time/h
Solvent
Yield/% Mn PD [a]
D/0C
DJ-D-13-A 0.1 50 30 1 64 10683 -571
DJ-D-13-B 0.2 200 50 1 84 40522 -1616.5
THF
Rh catalyst(2 mol%)
O OSS
OO
O
O
KI/DMF/ 80oCN N
N
N
N
NO
NH
HNO
O
SO O N N
?
A yellow solid product.[α]D
20.7 = -755.5 0 (4 mg/10 mL MeCN)[α]D
20.7 = +743.0 0 (4 mg/10 mL DMF)
O
NH
HNO
O
THF
Rh catalyst(2 mol%)
O OSS
OO
O
O
SO O
poor resolution of polymersmall optical rotationsmall molecular weight
Summaries and Plans
Axially Dissymmetric Compounds• Synthesis of model compounds based on 1,1’-binaphthyl.
• A series of properties relating with chiroptical switches.
• Near-infrared chiroptical properties.
• Achieving the designed tasks.
• Optimized chiroptical properties via optimizing the conditions of measures.
• Theoretical calculation:
Understanding the relationship between the chiroptical properties and structures.
Improving the properties by redesigning the structures.
7. Synthesis of polymer based on the model compound.
8. Properties of polymer:
In solution.
Film.
Helical Polymers• Synthesis of monomers containing:
Alkynyl.
Chiral center.
Bromomethyl or sulphonic acid ester or group brominated.
6. Introduction of alkynyl bond after bromination.
3. Not achieving the designed tasks.
8. The main problems:
The small optical rotation.
The small molecular weight
The poor solubility.