Toward to Highly Efficient Near-Infrared

Chiroptically Switching Materials:-- Design, Synthesis and Properties

Reporter: Jian Deng

Supervisor: Naiheng Song (Peking University)

Zhixing Su (Lanzhou University)

5th East-Asian Polymer Conference_ June 3-6, 2008, Shanghai, China.

• Background

• Research Hypothesis

• Results and Discussions

• Conclusions

• Acknowledgements

Outline

Chirality

“I call any geometrical figure, or group of points, chiral, and say that it has chirality, if its image in a plane mirror, ideally realized, cannot be brought to coincide with itself.”

Lord Kelvin, Baltimore Lectures, 1904

Chiroptical Properties

Optical Rotation: different rates of Right and Left Hand circularly polarized light transmitted in chiral materials.

• Specific Rotation and Molar Ellipticity• Electronic structure• External conditions, including temperature, transmittance length, concentration, electronic field, and light field

[ ]t lcαα λ =

Circular Dichroism:different absorbance of Right and Left Hand circularly polarized light transmitted in chiral materials.

2.303 ( - )180[ ]4

l rlc lc

ε εθθπ

= = ×

Nicolprismpolarizer

Unpolarizedlight

Incident plane-polarized light

Polarimeter tube containing solution of optical isomer

Nicol prismanalyzer

Emergent lightwith rotated plane of plarization

PhotonBean

OpticallyActiveSample

PreferentialAbsorbance of Right Handpolarization

CD signalRight and Left Hand circularly polarized light

PhotonBean

OpticallyActiveSample

PreferentialAbsorbance of Right Handpolarization

CD signalRight and Left Hand circularly polarized light

Potential Applications:

Display and Optical Modulation Bragg Reflection and Chiral Lasing Data Storage Chiral fluorescent sensing Nonlinear Optics

Chrial Photonics

Helical waveguide usable for selective filtering, scattering and

coupling

Chiroptical switch triggered by light

Feringa, Ben L. et al.

Chiral photonics, Inc.

Chiral Waveguide and Polarization Control

NIR Chiroptically Active Materials

Strong Signal Changes (Ellipticity or Optical Rotation )Control of External Field (e.g., Electric or Light Filed)

Huang, X.F.; Rickman, B.H.; Borhan, B.; Berova, N.; Nakanishi, K.

J.Am.Chem.Soc., 1998,120, 6185.

Structure Factors

Rosenfeld Equation

2 2

2 2

296[ ( )]

3i i

i i

n RN

hcλ λπψ λ

λ λ+=

−∑

Appropriate introduction of electro/photochromic chromophores into a suitable chiral structure should lead to Electrically or Optically controllable chiroptical properties.

Structural Design I

*(R) -1

N N+ N N N Nee

-e -e

viologen violene quinonoid

E1/2£½ -0.42 V E1/2£½ -0.90 V

o

60 , 3.9AoijRα = =

Molecular Design

Conformational Differences

Relationship between Structure and Properties

Structural Design II

60 o - 120 o

O

O

N

N

N

N

(R)-1

PF64 xO

O

N

N

N

N

(R)-2

PF64 x

3o

A

Synthesis of Model Compounds

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% yield

MeSO2Cl, NEt3, DMAP/CH2Cl2

92.5% yield

LiBr

DMSO

50% yield1)MeCN

2)KPF6

74% yield(R)-BEB

(R)-BINOL (R)-BE (R)-BES

(R)-BEBP

N N

1) DMF (110 oC)

2) KPF6

O

O

N

N

N

N (R)-1

Br

90% yield

4x PF6

2) KPF6, 11% yield

1) MeCN, 110 oC

(R)-2

O

O

N

N

N

N

4x PF6

Br

Br

OH

OH

2x PF6

-40

-20

0

20

40

60

-1.2-1-0.8-0.6-0.4-0.20

Voltage (V)

Cu

rre

nt

(mA

)

(R) -1(R) -2

-50

-40

-30

-20

-10

0

10

20

30

200 300 400 500 600 700 800

Wavelength (nm)

Mo

lar

Ell

ipti

cit

y (

x105

deg

cm

2 /d

mo

l)

-100

-80

-60

-40

-20

0

20

40

60

Ell

ipti

cit

y (

md

eg

)

CD

(R )-2

(R )-1CV

-55

-45

-35

-25

-15

-5

5

0 1 2 3 4 5

number of reductions

Elli

pti

cit

y (

md

eg

)

660 nm

410 nm

CS

0

0.2

0.4

0.6

0.8

1

1.2

1.4

200 300 400 500 600 700 800

Wavelength (nm)

Ab

sorb

ance

(a.

u.)

UV-Vis

(R )-2

(R )-1

UV-vis Spectroelectrochemisty Chiroptical Properties

18.2 Å

7.5 Å

2.80

Optimized Geometries

= Electrochromic Chromophores

axially chiralmain-chain

axially chiralmain-chain

Zentel, R.;Muller, M. Macromolecules, 1994, 27, 4404.

Polymer Design

Synthesis of PolymersPd(PPh3)4, K2CO3

THF/H2O (v/v, 1/1 )

MeSO2Cl, NEt3, DMAP

Br

Br

OOH

OOH

B B

C8H17 C8H17

O

O O

O+

95 oC

C8H17 C8H17

OOH

OHO

nCH2Cl2

C8H17 C8H17

OOSO2Me

OMeO2SO

n

(R)-DBB

N N+

I

KI / DMF

80 oC

KI / DMF80 oC

C8H17 C8H17

OI

OI

n

P3

P1P2

C8H17 C8H17

O

N+

O

N+

N+

N+

I

I

m

P4

Mn = 4.4¡Á104, PDI = 1.62; [¦Á]D

20 = -462.0o ([m]D20 = -3516o ) (c 0.4, DMF)

[¦Á]D20 = -341.5o ([m]D

20 = -3128o ) (c 0.4, DMF)

[¦Á]D20 = - 263.0 o ([m]D

20 = -3265o ) (c 0.4, DMF)

I

I

P4

P2

P1

1H NMR

-16

-12

-8

-4

0

4

280 330 380 430 480 530 580 630 680 730

Wavlength (nm)

[θ]×

10

4

(d

eg c

m 2

dm

ol -1

)

P4

P1

P2

CD

-14

-10

-6

-2

2

6

10

14

380 430 480 530 580 630 680 730

Wavelength (nm)

[θ]

(x10

5 deg

cm

2 /dm

ol)

-14

-10

-6

-2

2

6

10

14

[θ]

(x10

3 d

eg c

m2/d

mo

l)P4

(R )-1CD

UV-vis Spectroelectrochemisty

0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -1.2-20

0

20

40

60

80

Cu

rre

nt

mA

（）

Voltage (V)

CV

250 350 450 550 650 750

Wavelength (nm)

Ab

so

rba

nc

e (

a.u

.)

UV-vis

Chiroptical Properties

-16

-12

-8

-4

0

4

280 330 380 430 480 530 580 630 680 730

Wavlength (nm)

Mo

lar

Elli

pti

city

(×

10

4deg

cm

2 d

mo

l -1)

P4

P1

P2

0

500

1000

1500

2000

2500

3000

3500

4000

[ φ] D

an

d [m

] D (

de

g c

m2 m

ol-1

)

(R )-DBB P1 P2 P4(R )-BBEBPP

手性光学性质

R minor-groove polybinaphthyltransoid conformation

R major-groove polybinaphthylcisoid conformation

interaction 1

interaction 2

interaction 3

Different Sign

Different Magnitude

Different Wavelength

A structural model correlating geometric factors with magnitude of

chiroptical properties was established and used to aid the structural

design of two novel chiroptical molecular switches [(R)-1 and (R)- 2]

that exhibited for the first time very large NIR chiroptical switching

properties.

A novel type of optically active polymer bearing electrochromic

viologens at side chains and with minor-groove cisoid main-chain

conformation was successfully prepared.

The polymer showed pronounced redox-based UV-vis and CD

spectral changes and good chiroptically switching properties.

Conclusions

Thanks for your attentions !