A New Fluorescent and Electrochromic Polymer

from 4-(Carbazol-9-yl)triphenylamine

Hui-Min Wang (王惠民), Sheng-Huei Hsiao* (蕭勝輝)

Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, 1, Sec.

3 Chunghsiao East Rd., Taipei 10608, Taiwan

E-mail: shhsiao@ntut.edu.tw

A new carbazolyl-substituted triphenylamine derivative, 4-(carbazol-9-yl)triphenylamine, was synthesized and used to build an electroactive polymeric film on the ITO-glass surface by

electrochemical oxidative coupling reactions. The elecrtrogenerated films showed two reversible oxidation redox couples on their cyclic voltammograms. The electrogenerated polymer

films exhibited reversible electrochemical processes and stable color changes upon electro-oxidation, which can be switched by potential modulation. The remarkable electrochromic

behavior of the film is clearly interpreted on the basis of spectroelectrochemical studies.

TABLE 2 Optical and Electrochemical Properties of Monomers and Polymers

1. L. Groenendaal, F. Jonas, D. Freitag, H. Pielartzik, J. R. Reynolds, Adv. Mater. 2000, 12, 481.

2. P. M. S. Monk, R. J. Mortimer and D. R. Rosseinsky, Electrochromism and Electrochromic Devices, Cambridge University

Press, Cambridge, UK, 2007.

3. J.-F. Morin, M. Leclerc, D. Ade`s, A. Siove, Macromol. Rapid Commun. 2005, 26, 761.

4. R.F. Nelson, R.N. Adams et. al. J. Am. Chem. Soc. 1966, 88, 3498.

5. R.F. Nelson, R.N. Adams, J. Electrochem. Soc. 1968, 115, 1159.

6. J.F. Ambrose, L.L. Carpenter, R.F. Nelson, J. Electrochem. Soc. 1975, 122, 876.

UV-Vis absorption and PL spectra

Spectroelectrochemistry

Basic Characterization

Scheme 1. Synthetic route of monomers TPACz and MeOTPACz

Polymer

Code

In Solutiona As Solid Filmd Oxidation Potential Energy Levels

λmaxabs

(nm)

λmaxPL

(nm)b

ΦPL

(%)c

λmaxabs

(nm)

λonsetabs

(nm)

λmaxPL

(nm)

E1/2Ox1

(V)

E1/2Ox2

(V)

E1/2Ox3

(V)

Egf

(eV)

HOMOg

(eV)

LUMOh

(eV)

TPACz 294, 305 392 4.5 298, 311 364 － 0.96 1.42 － 3.41 5.31 1.91

PTPACz 294, 347 417 28.7 298, 360 441 424 0.88 1.47 － 2.81 5.24 2.17

MeOTPACz 294 395 3.1 298, 310 375 － 0.71 1.30e － 3.30 5.07 1.77

(MeOTPACz)2 294 408 2.2 298, 310 390 － 0.71 1.20 1.46 3.18 5.07 1.89 a Measured in dilute solutions in CH2Cl2 at a concentration of about 1 x 10-5 mol/L. b Excited at the absorption maximum. c The fluorescent quantum yield was calculated in an integrating

sphere with quinine sulfate as the standard (ΦPL = 54.6%). d Drop-coated from CH2Cl2 solution. e Irreversible peak potential (Ep,a). f Optical band gap obtained from Eg = 1240/λedge.

g The

HOMO energy levels were calculated from E1/2 and were referenced to ferrocene (4.8 eV). h LUMO = HOMO - Eg

Cyclic Voltammograms

Electrochromic Devices based on PTPACz

ABSTRACT

INTRODUCTION

EXPERIMENTAL

REFERENCES AND NOTES

MOTIVATION

RESULTS AND DISCUSSION

PTPACz

Electrosynthesis and electrochromic properties of

electroactive polymers from triphenylamine-containing

carbazole derivatives

TPACz

N

N

MeOTPACz

N

N

H3CO OCH3

Electropolymerization

Fluorescent and electrochromic material

Interesting electrochromism and multi-coloring stage

Exceptional optical contrasts and switching times, and stabilitie J. Ambrose et. al. J. Electrochem. Soc.

1975, 122, 876 R.N. Adams et. al. JACS, 1966, 88, 3498.

Literature Discussion

N

NH2

OCH3

I

I

2

2

Ullmann Reaction

Cu, K2CO3, TEGDME

N

N

N

N

H3CO OCH3

TPACz

MeOTPACz

N-(4-aminophenyl)carbazole

Oxidation and Dimerization of Triphenylamine or Carbazole

TPACz

Brown Crystals

mp: 172~174 oC

yield: 61%

MeOTPACz

Brown Crystals

mp: 126-127 oC

yield: 55%

Monomer TPACz MeOTPACz

Molecular

structure

Color pale brown crystal pale brown crystal

Solvent acetonitrile acetonitrile

Size 0.40 x 0.34 x 0.14 mm 0.44 x 0.24 x 0.14 mm

Monoclinic

C2/c

a = 27.8714(16)

b = 9.7479(5)

c = 19.7603(9) Å

α = 90o

β = 126.516(3)o

γ = 90o

a = 9.2535(2)

b = 13.8327(3)

c = 19.4070(5) Å

α = 90o

β = 90o

γ = 90o

Density Dc = 1.264 Mg/m3 for

Z = 8 and V = 4314.7(4) Å 3

Dc = 1.258 Mg/m3 for

Z = 4 and V = 2484.03(10) Å 3

N

N

TPACz PTPACz

Electropolymerization

0.1 M Bu4NClO4/ACN

N

N

n

N

N

H3CO OCH3

Electropolymerization

0.1 M Bu4NClO4/ACN

N

N

H3CO OCH3

N

N

OCH3H3CO

MeOTPACz

(MeOTPACz)2

Monomer Synthesis Electrochemical Polymerization

(MeOTPACz)2

Scheme 2. Synthetic route of polymer PTPACz and dimer (MeOTPACz)2

Figure 1. UV-Vis absorption and PL spectra of the dilute

solutions of (a) TPACz and PTPACz (b) MeOTPACz and

(MeOTPACz)2 in CH2Cl2 (1 x 10-5 M).

Figure 2. Cyclic voltammograms of monomers and

polymers in 0.1 M Bu4NClO4/CH3CN solution at scan

rate 50 mV/s.

TABLE 1 Crystal data by single crystal X-ray analysis

Figure 4. Spectroelectrochemical spectra of PTPACz and (MeOTPACz)2 with applied potential between 0

and +1.8 V in 0.1 M Bu4NClO4/CH3CN solution.

Scheme 3. Two different electropolymerization routes of TPACz in theory

Figure 5. (a) Photos of sandwich-type ITO-coated glass

electrochromic device, using PTPACz as active layer. (b)

Schematic illustration of the structure of the ECD.

Molecular Orbitals

Nature of Linkages in

the Polymer PTPACz

Figure 3. Optimized geometry and spatial

distributions of the HOMO and LUMO

levels for TPACz

John R. Platt

Professor of Physics

& Biophysics

Practical applications of electrochromic devices include

the smart windows, information displays, rear-view

mirrors in the automobile, protection glassware, etc.

A reversible optical change observed in a material because of

an applied external voltage is defined as electrochromism

What is Electrochromism ?

MARIO LECLERC

Conjugated Polymeric Materials

N

56

7

8 1

2

34

H9

Advantages

MARIO LECLERC

• A cheap starting material

• The nitrogen atom can beeasily functionalized

• Its fully aromatic configuration provides good

chemical and environmental stabilities

• Carbazole units can be linked at different

positions.

Many other aromatic polymers were intensively investigated. Such

as polyanilines, poly(p-phenylene)s, polythiophenes, polypyrroles,

poly(2,7-fluorene)s, poly(3,6-carbazole)s etc.

NH

n

S

n

N

n

H R R

n

N

n

R

Polyanilines Polythiophenes Polypyrroles Poly(3,6-carbazole)sPoly(2,7-fluorene)s