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.