Fh

Ga

b

a

ARRA

KPOEEH

1

fioosae

mrigt[o

matrwopf

0h

Synthetic Metals 180 (2013) 25– 31

Contents lists available at ScienceDirect

Synthetic Metals

journa l h om epage: www.elsev ier .com/ locate /synmet

errocenyl dithiophosphonate functionalized inorganic–organicybrid conductive polymer with green color in neutral state

ülbanu Koyundereli C ılgı a, Mehmet Karakusb, Metin Akb,∗

Pamukkale University, Technology Faculty, Materials Science and Engineering Department, Denizli, TurkeyPamukkale University, Faculty of Art and Sciences, Chemistry Department, Denizli, Turkey

r t i c l e i n f o

rticle history:eceived 11 June 2013eceived in revised form 6 July 2013ccepted 23 July 2013

a b s t r a c t

We report the synthesis and the characterization of the first electroactive ferrocenyl dithiophospho-nate functionalized inorganic–organic hybrid conductive polymer. Electropolymerization was realizedin boron trifluoride diethyl etherate (BFEE) with an applied potential of 1.5 V. Surface morphological,spectroelectrochemical, colorimetric and redox properties of polymer were investigated. Spectroelec-

eywords:olymersptical materialslectrochemical techniques

trochemical and colorimetry studies have shown that ThFc has green color in neutral state.The reaction of the ferrocenyl dithiophosphonate and nickel(II) acetate gave rise to square-planar

nickel(II)complex (ThFc–Ni). ThFc–Ni complex copolymerize with thiophene and spectroelectrochemicalproperties of copolymer were also investigated.

lectrochemical propertiesybrid metallopolymers

. Introduction

Inorganic–organic materials are currently a widely exploredeld of research since their extraordinary properties are basedn the combination of the different building blocks. Incorporationf inorganic components in the organic polymeric structure havehown promising applications in various fields of chemistry suchs organic synthesis, biotechnology, catalysis, electronics, polymerstc [1,2].

One of the important class of these materials is hybrid poly-ers. Hybrid polymers can be distinguished into two types with

espect to their structures. Inorganic–organic polymers (IOP) havenorganic elements in the main chain and also have an organic sideroup. Organic–inorganic hybrid polymers have carbon atoms inhe main chain and contain inorganic elements in the side groups3]. One important class of hybrid polymers is the one where therganic component is conducting polymers [2,4].

Conducting polymers (CPs) with a regular alternating arrange-ent of an aromatic �-electron system are currently receiving

ttention stemming not only from their high conductivities inhe doped state but also from a variety of optoelectronic andedox properties [5,6]. One of these properties is electrochromism,hich is defined as the reversible electromagnetic absorbance

r transmittance change in response to an externally appliedotential. Electrochromism results from the generation of dif-erent electronic absorption bands in the visible region, which

∗ Corresponding author. Tel.: +90 258 2963595; fax: +90 258 2963535.E-mail address: metinak@pau.edu.tr (M. Ak).

379-6779/$ – see front matter © 2013 Elsevier B.V. All rights reserved.ttp://dx.doi.org/10.1016/j.synthmet.2013.07.017

© 2013 Elsevier B.V. All rights reserved.

arise from the changes between at least two redox states [7,8]Conjugated polymers have attracted considerable interest as elec-trochromic materials since subtle modifications to the monomercan significantly alter the spectral properties of the polymer.Switching properties between their oxidized (doped) and charge-compensated (neutral) states can be repeated over many redoxcycles. CPs that have one of the three complementary colors (red,green, and blue) in the reduced state are key materials towarduse in electrochromic devices and displays. The ability to havethree complementary colors, red, green, and blue (RGB) consti-tutes an important step forward to the use of conducting polymersin polymeric electrochromic devices (PECDs) [9]. Having greencolor in neutral state is an interesting property of the polymer.Although many red and blue colored polymers in their neutralform have been reported, only a few reports are found in literaturefor green colored CPs due to the difficulty to obtain appropriateabsorptions required in the visible region to reflect the green color[9,10].

Since absorption at only one dominant wavelength is requiredto give blue or red, these can be obtained relatively easily by tuningthe CP’s band gap. At least two absorption bands (blue and red) arerequired to observe a green color [11].

Green color in neutral state was achieved with the synthesisof a polymer backbone containing two well-defined, isolated, con-jugated systems which absorb blue and red light. One chain haselectron donor and acceptor groups to decrease the band gap, which

results in the absorption of the blue light at wavelengths longerthan 600 nm, and the other chain absorbs in the red at wavelengthsbelow 500 nm. Sonmez and Toppare research groups conductedbreakthrough researchs on this subject [9–15].

26 G.K. C ılgı et al. / Synthetic Metals 180 (2013) 25– 31

S

O

P

S

SHS

P

SS

P

S

2S

OH

+toluene

2 BFEE

nS

O

P

S

SHV1.5

Fe

Fe

Fe Fe

ic rout

p�te(tbtcwa

didrabinntw

2

2

fl(

c(are

Scheme 1. The synthet

Hybrid metallopolymers [16–19] that consist of conjugatedolymers with transition metals linked to or directly in the-conjugated polymer backbone is a promising group of elec-

rochromic materials [20–24]. Because their chromophoric prop-rties, resulting from low-energy metal-to-ligand charge transferMLCT), intervalence charge transfer (IVCT), intraligand chargeransfer (ILCT) and related visible region electronic transitions, cane tuned via the molecular design of ligands and complexes, andheir multi-redox natures of the ligand-based and metal-based pro-esses can be switched with color changes in the regular potentialindow, these polymeric systems have greatly expected to use in

ll-solid-state electrochromic devices.In this work, we sythesized first electroactive ferrocenyl

ithiophosphonate functionalized monomer bearing organic andnorganic groups namely O-2-(thiophen-3-yl)ethyl ferrocenylithiophosphonate (ThFc). Electropolymerization of ThFc wasealized only in boron trifluoride diethyl etherate (BFEE) withn applied potential of 1.5 V. BFEE serves not only as the solventut also as the supporting electrolyte, hence no other support-

ng electrolyte is needed. The reaction of the ligand (ThFc) andickel(II) acetate in CHCl3/CH3COOH gave rise to square-planarickel(II) complex(ThFc–Ni). ThFc–Ni complex copolymerize withhiophene and spectroelectrochemical properties of copolymerere investigated.

. Materials and methods

.1. Chemicals and instrumentations

2-(3-Thienyl)ethanol, toluene, acetic acid, acetonitrile, borontri-uoride ethylether (BFEE) was purchased from Aldrich. ThiopheneTh) (Aldrich) were distilled prior to use.

Three-electrode cell geometry was used in all electrochemi-al experiments. ITO (indium tin oxide) coated glass rectangular

0.9 cm × 2.7 cm) slide was used as the working electrode. Ptnd Ag wires were used as the counter and reference electrodesespectively. All potential values are referred to Ag/Ag+ refer-nce electrode. An ivium potentiostat/galvanostat interfaced with

O

P

S

S

S

Ni

O

P

S

S

S

Fe

Fe

ThF c-N i

S

O

P

S

SH2

ThF c

Fe

Ni( CH3COO )2

CHCl3

Scheme 2. Synthesis of nickel comple

ThFc Poly(ThFc)

e for ThFc and P(ThFc).

a personal computer was used in all electrochemical measure-ments. In situ UV–vis spectroelectrochemical measurements werecarried out in three-electrode quartz cell. The working electrodewas an ITO glass slide; Ag and Pt wires were used as the ref-erence and auxiliary electrodes, respectively. The spectra wererecorded with a Diode Array UV-vis spectrophotometer (Agilent8453), interfaced with a PC. The structure of the monomer wasconfirmed by NMR and IR spectral analysis. 1H NMR spectra ofthe monomer were taken by using a Bruker-instrument NMR spec-trometer (DPX-400) with CDCl3 as the solvent. Nicolet 510 FTIRSpectrophotometer was used for FTIR studies. Colorimetry mea-surements were obtained by a Coloreye XTH Spectrophotometer(GretagMacbeth).

2.2. Synthesis of the ThFc

ThFc was synthesized by the reaction of [FcP(=S)(�-S)]2 with2-(3-thienyl)ethanol in toluene (Scheme 1). Detailed synthesisinformation is given below:

[FcP(=S)(�-S)]2 (0.50 g, 0.89 mmol) was reacted with the 2-(3-thienyl)ethanol (0.23 g, 1.78 mmol) in a 1:2 ratio in toluene(25 mL) to give the corresponding O-2-(thiophen-3-yl)ethyl-ferrocenyldithiophosphonate. The reaction was heated until allsolids were dissolved and a brown solution was obtained. The reac-tion mixture was filtered and the solution was cooled in a fridge at−18 ◦C. The yellow–orange crystalline product was filtered, driedunder vacuum and isolated in high-yield. Yield: 0.42 g (58%), m.p.:147–148 ◦C. Anal. calc. for C16H17FeOPS3 (%): C, 47.06; H, 4.19.Found: C, 47.01; H, 4.27.

2.3. Preparation of the Ni-complex of ThFc (ThFc–Ni)

A solution of nickel(II) acetate(0.07 g, 0.4 mmol) in CH3COOH(5 mL) was added to a solution of the O-2-(thiophene-3-yl)ethyl-4

ferrocenyl dithiophosphonate (0.42 g, 0.8 mmol) in CHCl3 (15 mL)and stirred at r.t. for 2 h. A brown solution was observed. After afew days, brown crystals were isolated by filteration, washed withn-hexane and dried in air. Yield: (48%), m.p.: >250 ◦C (Scheme 2).

S

O

P

S

S

S

Ni

O

P

S

S

S

Fe

Fe

P(ThFc-N i-co-Th )

S

S n

m

x of ThFc and P(ThFcNi-co-Th).

G.K. C ılgı et al. / Synthetic Metals 180 (2013) 25– 31 27

Fig. 1. 1H NMR (a), 13C NMR (b) and 31P NMR spectra (c) of the ThFc.

28 G.K. C ılgı et al. / Synthetic Metals 180 (2013) 25– 31

Fig. 2. 1H NMR (a) and 31P NMR spectra (b) of the ThFc–Ni.

-0.5 0.0 0.5 1.0 1.5-0.05

0.00

0.05

0.10

0.15a)

Potential (V)

Cu

rren

t D

en

sit

y (

mA

/cm

²)

-0.6 -0.3 0.0 0.3 0.6 0.9 1.2 1.5

-0.6

-0.3

0.0

0.3

0.6

0.9

1.2

1.5

b)

Potential (V)

Cu

rren

t D

en

sit

y (

mA

/cm

²)

Fig. 3. Cyclic Voltammograms of ThFc (a) and Th (b) in BFEE at 200 mV/s scan rate.

G.K. C ılgı et al. / Synthetic Metals 180 (2013) 25– 31 29

210-1

0

1

2

Potential (V)

Cu

rre

nt

De

ns

ity

(m

A/c

m²)

a)

1,51,00,50,0-0,5

-1

0

1

2

3

4

current decrea se

Cu

rre

nt

De

ns

ity

(m

A/c

m²)

Potanti al(V)

curren t in creas e

b)

i and

2e

stabewmcrw1

cgaTcIft(

3

1

ts

a

1(

T1CC7(

o

Fig. 4. Cyclic Voltammograms of ThFc–Ni (a) ThFcN

.4. Electrochemical polymerization and spectroelectrochemistryxperiments

For electropolymerization of ThFc and ThFc–Ni differentolvent/supporting electrolyte couples were investigated. Elec-ropolymerization of ThFc was realized only in BFEE with anpplied potential of 1.5 V. BFEE serves not only as the solventut also as the supporting electrolyte, hence no other supportinglectrolyte is needed. The oxidation/reduction behaviors of ThFcere investigated by cyclic voltammetry (CV) in BFEE. Experi-ents were carried out in an electrolysis cell equipped with ITO

oated glass plate as the working, Pt wire counter and Ag+/Ageference electrodes. Electrocopolymerization of ThFc–Ni (0.05 M)ith thiophene (0.01 M) was realized in ACN:BFEE (1:1, v/v) at

.8 V.Spectroelectrochemistry is the best way of examining the

hanges in optical properties of CPs upon applied voltage. It alsoives information on the electronic structure of the polymer suchs band gap (Eg) and the intergap states that appear upon doping.he film was deposited on ITO via potentiostatic electrochemi-al polymerization of ThFc in the BFEE at +1.5 V. P(ThFc) coatedTO was investigated by UV–vis spectroscopy in the monomerree BFEE by switching between 0.2 V and 1.0 V. Investigation ofhe spectroelectrochemistry of ThFc–Ni was realized in ACN:BFEE1:1, v/v).

. Results and discussions

Structures of the ThFc and ThFc–Ni were characterized 1H NMR,3C NMR and 31P NMR spectra. In the 1H and 13C NMR spectra,he zero chemical shift was assigned to TMS, while in the 31P NMRpectra ı = 0 corresponds to orthophosphoric acid (H3PO4).

Characteristic peaks for ThFc in 1H NMR spectroscopy (Fig. 1a)re listed below:

1H NMR (400 MHz, CDCl3) ı: 7.18 (q, 1H), 6.99 (dd, 1H), 6.91 (dd,H), 5.76 (s, 1H), 4.55–4.45 (m, 2H), 4.38–4.33 (m, 2H), 4.31–4.18m, 7H), 2.97 (t, 2H). IR (cm−1): 655 (�asym PS2) and 589 (�sym PS2).

The 13C NMR (101 MHz, CDCl3) spectrum also confirmed thehFc structure (Fig. 1b). Ca: 137.77 ppm (s), Cb: 128.38 ppm (s), Cc:25.59 ppm (s), Cd: 121.82 ppm (s), Ce: 31.24 ppm (d, J = 8.00 Hz),f: 65.72 ppm (d, J = 6.42 Hz), C1: 74.20 ppm (d, 1JP,C = 176.72 Hz),2: 72.03 ppm (d, 2JP,C = 17.97 Hz), C2

/: 71.14 (d, 2JP,C = 15.33 Hz), C3:

1.55 (d, 3JP,C = 3.97 Hz), C3

/: 71.40 (d, 3JP,C = 4.77 Hz), C4: 70.36 ppms)

31P NMR (162 MHz, CDCl3) spectrum of the ThFc presented onlyne signal at ı: 86.46 (Fig. 1c).

Th (b) in (1:1 v/v) BFEE/ACN at 200 mV/s scan rate.

Structure characterization of the ThFc–Ni was also confirmedby 1H NMR and 31P NMR spectra. NMR spectra of the ThFc–Ni wereshown in Fig. 2. 1H NMR (400 MHz, CDCl3) ı: 7.24 (dd, 1H), 7.09 (m,1H), 7.01 (dd, 1H), 4.60 (dd, 2H, C5H4), 4.54 (m, 2H, OCH2), 4.38 (dd,2H,C5H4), 4.25 (dd, 5H, C5H5), 3.08 (t, 2H, CH2). 31P NMR (162 MHz,CDCl3) ı: 107 ppm.

Cyclic voltammogram of ThFc upon cycling from −0.6 to 1.6 V at200 mV/s scan rate is shown in Fig. 3a. In the first cycle ferroceneoxidation peak at 0.12 V was shifted to 0.27 V due to the polymer-ization of the monomer in second cycle. After subsequent cyclesferrocene oxidation peak remains under the oxidation peak of thepolymer [25]. Reduction peak observed at around −0.08 V. For com-parison, CV of the thiophene under the same conditions is given inFig. 3b. As seen in the voltammogram, oxidation of the polythio-phene takes place in a wide range of potantial range (0.0–1.1 V) andreduction of the polythiophene takes place at around −0.3 V. As canbe seen that gradual increases in the amplitude of the redox peakswere observed as a consequence of the repeated potential scans,indicative of the electropolymerization and subsequent depositionof the polymeric film at the ITO coated glass surface.

Cyclic voltammogram of ThFc–Ni upon cycling from −0.5 to2.2 V at 200 mV/s scan rate is shown in Fig. 4a. It was found thatthe ThFc–Ni underwent two redox processes; a reversible processattributed to the ferrocene moiety (anodic peak potential 0.60 Vand cathodic peak potential 0.27 V), and an irreversible oxidationprocess that had an anodic peak potential of ∼2.0 V presumably dueto oxidation of the thiophene. None of these conditions resulted information of a conductive, electroactive film.

It was found that ThFc–Ni could be electrodeposited with Th onITO coated glass slide using either CV, constant potential or con-stant current. The cyclic voltammograms obtained during growth(Fig. 4b) show the expected increase in current with increasingnumber of potential cycles, indicative of conducting electroactivepolymer growth. By comparison with CV growth of ThFc taken thesame conditions, the redox couple was identified as the ferroceneredox couple. The onset of oxidation of the co-monomers, after theoxidation of the ferrocene moiety, was 1.64 V.

Surface morphologies of polymers were investigated by scan-ning electron microscope. SEM micrograph of P(ThFc) (Fig. 5a) wasdifferent to the P(ThFcNi-co-Th) (Fig. 5b). It can be concluded fromSEM micrographs, P(ThFc) has more smooth structure when com-pared with P(ThFcNi-co-Th).

For spectroelectrochemical experiments, P(ThFc) film waspotentiostatically synthesized at 1.5 V on ITO electrode and thenits spectroelectrochemistry was investigated in a monomer freeBFEE solution (Fig. 6a). Polythiophene backbone absorption was

30 G.K. C ılgı et al. / Synthetic Metals 180 (2013) 25– 31

oStap

Fig. 7. Spectroelectrochemistry (a) and redox color of of P(Th) in BFEE; (b) bluecolor (L: 46, a:3, b: −26) at +0.8 V; (c) red color (L: 42, a: 36, b: 31) at −0.8 V. (For

Fo

Fig. 5. SEM micrographs of (a) P(ThFc) and (b) P(ThFcNi-co-Th).

bserved between 250 and 550 nm with a maximum at 390 nm.

pectroelectrochemical analysis showed that P(ThFc) has an elec-ronic band gap (due to �–�* transition) of 2.14 eV. Colorimetrynalysis has become an important technique for the electrochromicolymers, allowing the accurate measure of the color [26].

ig. 6. Spectroelectrochemistry (a) and redox color of P(ThFc) in BFEE; (b) blue color (L: 47,f the references to color in figure legend, the reader is referred to the web version of the

interpretation of the references to color in figure legend, the reader is referred tothe web version of the article.)

Colorimetry measurements were done via Minolta CS-100 spec-trophotometer. P(ThFc) revealed color changes between green andblue in the neutral and oxidized states respectively. Redox colorsof the P(ThFc) and corresponding L*a*b values are given in Fig. 6band c (Color of the PTh synthesized in the same conditions is givenin Fig. 7b and c).

Spectroelectrochemical characterization of polythiophene(PTh) synthesized under the same conditions is given in Fig. 7a.The spectroelectrochemistry studies of the P(Th) were studied byapplying potentials between −0.9 and +0.9 V in a monomer freeBFEE medium. The wavelength (�max) at which polymer shows�–�* transition was determined as 500 nm. The band gap (Eg) was

calculated as 1.91 eV.

P(ThFc-Ni-co-Th) film was potentiostatically synthesized at1.8 V on ITO electrode from ACN solution of the ThFc–Ni

a: 3, b: −30) at +1.2 V; (c) green color (L: 71, a: −27, b: 52) at 0.0 V. (For interpretation article.)

G.K. C ılgı et al. / Synthetic Me

Fig. 8. Spectroelectrochemistry (a) and redox color of of P(ThFcNi-co-Th) in BFEE-Abr

(wPboF

4

gpi(sEsdvpcg

A

(

R

[

[

[

[

[

[

[

[

[

[

[

[

[

[

[

CN (1:1); (b) blue color (L: 49, a: 1, b: −14) at +1.6 V; (c) yellow color (L: 77, a: −3,: 42) at −0.5 V. (For interpretation of the references to color in figure legend, theeader is referred to the web version of the article.)

0.05 M) and Th (0.01) and then its spectroelectrochemistryas investigated in a monomer free BFEE solution (Fig. 8a).

(ThFc-Ni-co-Th) revealed color changes between yellow andlue in the neutral and oxidized states respectively. Redox col-rs of the P(ThFc) and corresponding L*a*b values are given inig. 8b and c.

. Conclusion

We synthesized a novel monomer bearing organic and inorganicroups namely O-2-(thiophen-3-yl)ethyl ferrocenyl dithiophos-honate (ThFc). The reaction of the (ThFc) and nickel(II) acetate

n CHCl3/CH3COOH gave rise to square-planar nickel(II) complexThFc–Ni). ThFc–Ni complex copolymerize with thiophene andpectroelectrochemical properties of copolymer were investigated.lectropolymerization of ThFc was realized only in BFEE (with noupporting electrolyte) with an applied potential of 1.5 V. The oxi-ation/reduction behaviors of ThFc were investigated by cyclicoltammetry (CV). Surface morphology of ThFc was compared witholythiophene synthesized the same conditions. Spectroelectro-hemical and colorimetric studies have shown that P(ThFc) hasreen color in its neutral state.

cknowledgements

Authors gratefully thanks TBAG (111T074) and PAU-BAP2009KKP057 and 2011KKP018) projects.

eferences

[1] G. Kickelbick, Concepts for the incorporation of inorganic building blocksinto organic polymers on a nanoscale, Progress in Polymer Science 1 (2003)83–114.

[

[

tals 180 (2013) 25– 31 31

[2] A.F. Beleze, J.G.A. Zarbin, Synthesis and characterization of organic–inorganichybrids formed between conducting polymers and crystalline antimonic acid,Journal of the Brazilian Chemical Society 4 (2001) 542–547.

[3] K. Haas, K. Rose, Hybrid inorganic/organic polymers with nanoscale build-ing blocks: precursors, processing, properties and applications, Reviews onAdvanced Materials Science 5 (2003) 47–52.

[4] A.B. Gonc alves, A.S. Mangrich, A.J.G. Zarbin, Polymerization of pyrrole betweenthe layers of �-tin (IV) bis(hydrogenphosphate), Synthetic Metals 114 (2000)119–124.

[5] A. Yildirim, S. Tarkuc, M. Ak, L. Toppare, Syntheses of electroactive layers basedon functionalized anthracene for electrochromic applications, ElectrochimicaActa 14 (2008) 4875–4882.

[6] C.L. Gaupp, K. Zong, P. Schottland, B.C. Thompson, C.A. Thomas, J.R. Reynolds,Poly(3,4-ethylenedioxypyrrole). Organic electrochemistry of a highly stableelectrochromic polymer, Macromolecules 33 (2000) 1132–1133.

[7] M. Ak, L. Toppare, Synthesis of star-shaped pyrrole and thiophene func-tionalized monomers and optoelectrochemical properties of correspondingcopolymers, Materials Chemistry and Physics 2/3 (2009) 789–794.

[8] M. Ak, M.S. Ak, M. Güllü, L. Toppare, Optoelectrochemical propertiesof poly(5,12-dihydrothieno[3′ ,4′:2,3][1,4] dioxocino[6,7-b]quinoxaline-co-2,2′

bithiophene) and its electrochromic device application, Smart Materials andStructures 16 (2007) 2621–2626.

[9] G.E. Gunbas, A. Durmus, L. Toppare, Could green be greener? noveldonor–acceptor-type electrochromic polymers: towards excellent neutralgreen materials with exceptional transmissive oxidized states for completionof RGB color space, Advanced Materials 20 (2008) 691–695.

10] G. Sonmez, C.K.F. Shen, Y. Rubin, F. Wudl, A red, green and blue (RGB) poly-meric electrochromic device (PECD): the dawning of the PECD era, AngewandteChemie International Edition 43 (2004) 1498–1502.

11] G. Sonmez, H.B. Sonmez, C.K.F. Shen, R.W. Jost, Y. Rubin, F. Wudl, A processablegreen polymeric electrochromic, Macromolecules 38 (2005) 669–675.

12] A. Durmus, G.E. Gunbas, L. Toppare, New, highly stable electrochromic poly-mers from 3,4-ethylenedioxythiophene-bis-substituted quinoxalines towardgreen polymeric materials, Chemistry of Materials 19 (2007) 6247–6251.

13] A. Durmus, G.E. Gunbas, P. Camurlu, L. Toppare, A neutral state green polymerwith a superior transmissive light blue oxidized state, Chemical Communica-tions 31 (2007) 3246–3248.

14] S. Günes, D. Baran, G. Günbas, A. Durmus, A. Fuchsbauer, N.S. Sariciftci, L. Top-pare, A green neutral state donor–acceptor copolymer for organic solar cells,Polymer Chemistry 1 (2010) 1245–1251.

15] A. Balan, D. Baran, G. Gunbas, A. Durmus, F. Ozyurt, L. Toppare, One polymer forall: benzotriazole containing donor–acceptor type polymer as a multi-purposematerial, Chemical Communications 44 (2009) 6768–6770.

16] T.W. Hesterberg, X. Yang, B.J. Holliday, Polymerizable cationic iridium(III)complexes exhibiting color tunable light emission and their correspondingconducting metallopolymers, Polyhedron 29 (2010) 110–115.

17] P.D. Byrne, P. Muller, T.M. Swager, Conducting metallopolymers based on Aza-ferrocene, Langmuir 22 (2006) 10596–10604.

18] B.J. Holliday, T.M. Swager, Conducting metallopolymers: the roles of moleculararchitecture and redox matching, Chemical Communications 1 (2005) 23–36.

19] J. Buey, T. Swaager, Three-Strand conducting ladder polymers: two-step elec-tropolymerization of metallorotaxanes, Angewandte Chemie InternationalEdition 39 (2000) 608–612.

20] R. Scanu, P. Manca, A. Zucca, G. Sanna, N. Spano, R. Seeber, C. Zanardi, M.I.Pilo, Homoleptic Ru(II) complex with terpyridine ligands appended withterthiophene moieties. Synthesis, characterization and electropolymerization,Polyhedron 49 (2013) 24–28.

21] O. Clot, M.O. Wolf, B.O. Patrick, Electropolymerization of Pd(II) ComplexesContaining Phosphinoterthiophene Ligands, Journal of the American ChemicalSociety 123 (2001) 9963–9973.

22] E. Turac, E. Sahmetlioglu, A. Demircan, L. Toppare, Synthesis and char-acterization of conducting copolymer of trans-1-(4-methyl-3′-thienyl)-2-(ferrocenyl)ethene with EDOT, Journal of Applied Polymer Science 126 (3)(2012) 808–814.

23] E. Turac , M. Ak, E. Sahmetlioglu, M.K. Sener, M.A. Kaya, Synthesis and character-ization of poly{2-[3-(1H-pyrrol-2-yl)phenyl]-1H-pyrrole} and its copolymerwith EDOT, Russian Journal of General Chemistry 81 (12) (2011) 2510–2516.

24] P. Camurlu, N. Karagoren, Clickable, versatile poly(2,5-dithienylpyrrole) deriva-tives, Reactive and Functional Polymers 73 (6) (2013) 847–853.

25] R. Back, R.B. Lennox, Electrochemical investigation of novel polymerizable thio-phene/ferrocene conjugates, Langmuir 8 (1992) 959–964.

26] B.C. Thompson, P. Schottland, K. Zong, J.R. Reynolds, In situ colorimetric analysisof electrochromic polymers and devices, Chemistry of Materials 12 (6) (2000)1563–1571.