WO2009126118A1

WO2009126118A1 - Unique processable green polymer with a transmissive oxidized state for realization of commerical rgb based electrochromic device applications

Info

Publication number: WO2009126118A1
Application number: PCT/TR2008/000035
Authority: WO
Inventors: Levent Kamil Toppare; Gorkem Emrullah Gunbas; Asuman Durmus
Original assignee: Levent Kamil Toppare; Gorkem Emrullah Gunbas; Asuman Durmus
Priority date: 2008-04-10
Filing date: 2008-04-10
Publication date: 2009-10-15
Also published as: TR201008266T2

Abstract

In the present invention a method for synthesis of neutral state green polymer PDOPEQ) is developed. The method developed in this invention is characterized by; a) obtaining 2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-dibromoquinoxaline, b) b) obtaining tributyl (2,3-dihydrothieno[3,4-b][l,4]dioxin-5-yl)stannane c) c) Using coupling to attach donor EDOT moieties to the acceptor quinoxaline unit to give the title compound (DOPEQ) in satisfactory yields; d) obtaining neutral state green polymer (PDOPEQ) by using either electrochemical or chemical methods. The polymers synthesized up to date mainly absorb/reflect blue and red colors in the reduced state. Conversely, to obtain a green colored polymer in the reduced state, one should have two absorption bands centered at the blue and red regions of the visible spectrum and moreover, these absorption bands should be manipulated in the same manner at applied potentials.

Description

UNIQUE PROCESSABLE GREEN POLYMER WITH A TRANSMISSIVE

OXIDIZED STATE FOR REALIZATION OF COMMERICAL RGB BASED

ELECTROCHROMIC DEVICE APPLICATIONS

FIELD OF INVENTION

Realization of commercial RGB based polymer electrochromic device applications can only be achieved by processable materials having three complementary colors in the reduced state and that are transparent in oxidized state. The present invention highlights the synthesis of first processable green polymer with a transmissive oxidized state. The polymer revealed superior optical contrast in the visible region with fast switching times and robust stability. Hence this material is the paramount candidate for completion of RGB color space through commercial polymeric electrochromics.

STATE OF THE ART

The documents published in the literature as state of the art of the present invention are listed below.

[1] N. S.Sariciftci, D.Braun, C.Zhang, V.Srdanov, A. J. Heeger, G.Stucky, F.Wudl, App. Phys. Lett. 1993, 62, 585.

[2] J. H.Burroughes, D. D. C.Bradley, A. R. Brown, R. N.Marks, K.Mackay, R. H.Friend, P. L.Burns, A. B.Holmes, Nature 1990, 347, 539. [3] N.Stutzmann, R. H.Friend, H.Sirringhaus, Science 2003, 299, 1881.

[4] D. T.McQuade, A. E.Pullen, T. M.Swager, Chem. Rev. 2000, 100, 2537. [5] A. Argun, A. Cirpan, J. R. Reynolds, Adv. Mater. 2003, 15, 1338.

[6] F. R.Denton, A.Sarker, P. M.Lahti, R.O.Garay, F.E.Karasz, J. Polym. ScL, Part A: Polym. Chem. 1992, 30, 2233. [7] K.Yoshino, P.Love, M.Onoda, R.Sugimoto, Jpn. J. Appl.Phys., Part 2: Lett. 1988, 27, L2388.

[8] G.Sonmez, I.Schwendeman, P.Schottland, K.Zong, J.R.Reynolds, Macromolecules 2003, 36, 639.

[9] G.Heywang, F.Jonas Adv. Mater. 1992, 4, 116. [10] R.Hanna, M.Leclerc, Chem. Mater. 1996, 8, 1512. [11] G.Sonmez, H. B.Sonmez, C. K. F.Shen, R. W.Jost, Y.Rubin, F.Wudl, Macromolecules 2005, 38, 669.

[12] C. G.Granqvist, A.Azens, A.Hjelm, L.Kullman, G.A.Niklasson, D.Ronnow, M. S.Mattsson, M.Veszelei, G.Vaivars, Solar Energy 1998, 63, 199. [13] O.Bohnke, C.Bohnke, S.Amal, Mater. Sci. Eng., B 1989, B3(l-2), 197.

[14] G.Sonmez, H. B.Sonmez, J. Mater. Chem. 2006, 16, 2473.

[15] G.Sonmez, C. K. F.Shen, Y.Rubin, F.Wudl, Angew. Chem., Int. Ed, 2004, 43, 1498 .

[16] A.Durmus₅ G. E.Gunbas, P.Camurlu, L.Toppare, Chem. Commun., 2007, 31, 3246.

[17] Sonmez G., Chem. Commun. 2005, 42, 5251-5259. [18] A.Durmus, G.E.Gunbas, L.Toppare Chem. Mater. 2007, DOI: 10.1021/cm702143c [19] G.E.Gunbas, A.Durmus, L.Toppare, Adv. Mater., 2008, 20 , 691 [20] B.Mohr, V.Enkelmann, G.Wegner J. Org. Chem. 1994, 59, 635.

[21] A. B.Da Silveria Neto, A. L.Sant'Ana, G.Ebeling, S. R.Goncalves, E. V. U.Costa, H. F.Quina, J.Dupont Tetrahedron, 2005, 61, 10975. [22] Y.Tsubata, T.Suzuki, T.Miyashi, Y. Yamashita J. Org. Chem. , 1992, 57,6749.

[23] C.Chen, Y.Wei, J.Lin, M. V. R. K.Moturu, W.Chao, Y.Tao, C.ChienJ Am. Chem. Soc, 2006, 128, 10992.

[24] S. S.Zhu, T. MSwagerJ Am. Chem. Soc, 1997, 119, 12568.

[25] G.Sonmez, G.Meng , Q.Zhang, F.Wudl, Adv. Funct. Mater., 2003, 13, 726. [26] A.Berlin, G.Zotti, S.Zecchin, G.Schiavon, B.Vercelli, A.Zanelli, Chem. Mater. 2004, 16, 3667.

The reference numbers of the publications are shown in the description in brackets below.

Since the discovery of conductivity in polyacetylene upon doping, conductive polymers turned out to be a major research era and became key materials in many applications such as, photovoltaics^[1], polymer light emitting diodes ^[2], field-effective transistors^[3], sensors^[4] and electrochromism^[5]. Although these exciting materials revealed excellent properties in many areas of research in last decades, the demand for processable conducting polymers emerged very soon. Since that time, a number of methodologies have been developed to overcome this significant drawback. Most common and effective ones were shown to be synthesis of soluble precursors which forms a conductive coating upon heat treatment^⁶¹ and introduction of alkyl side chains^[71 in the polymer structures. It is clearly stated that alkyl side chains not only enhance the ease of processing but also modify the electronic properties of the conjugated polymers¹⁸¹. The oxidation potential of the polymers¹⁹¹, stability of the oxidized state^tl0] and band gap^[U1 can drastically be altered upon insertion of strong electron-donating alkoxy side chains in the polymer backbone. Reversible color changes observed in a conjugated polymer system upon doping and dedoping process, namely electrochromism, have received a great attention over the past years since electrochromic polymers can be utilized in many applications like smart windows^¹²¹, displays^¹³¹ and data storing devices^¹⁴¹. For realization of polymeric electrochromic based display devices, three additive or subtractive primary colored materials in the neutral state should be attained. Unfortunately, most of the polymers synthesized up to date mainly absorb/reflect blue and red colors in the reduced state. The main reason is the one dominant wavelength character of these colors. Conversely, to obtain a green colored polymer in the reduced state, one should have two absorption bands centered at the blue and red regions of the visible spectrum and moreover, these absorption bands should be manipulated in the same manner at applied potentials¹¹⁵¹.

These phenomena resulted in only two neutral state green polymers in literature up to date^{[15> 16}I Besides the significant importance of the neutral state color of electrochromic materials, the transmittance in the oxidized state is also vital. As Sonmez et al. indicated, the residual brown color in the oxidized form of PDDTP (poly(2,3-di(thien-3-yl)-5,7-di(thien-2- yl)thieno[3,4-b]pyrazine)), the first example of a true green polymer, was the major problem that obstruct the potential use^[17]. This drawback was eliminated by our group, with poly(4,7- di(2,3-dihydro-thieno[3,4-b][l,4]dioxin-5-yl)benzo[l,2,5]thiadiazole) (PBDT) which produces a saturated green color in the neutral and a highly transmissive light blue color in the oxidized state¹⁶. Hexyl substituted soluble derivative of PDDTP, also revealed a brown color in the oxidized state as expected¹"¹. The monomer of PBDT is not convenient for alkyl group substitution; hence we prepared some new exciting EDOT substituted quinoxaline monomers which polymerize to give materials that are green in the neutral and highly transmissive in the oxidized state and are susceptible for alkyl group substitution¹¹⁸' ¹⁹¹. In the present invention the synthesis and electrochromic properties of the first solution-processable neutral state green polymer with a highly transmissive oxidized state has been highlighted. AIMS OF THE INVENTION

• In the present invention,

• Development of the syntheses of first processable green polymer with highly transmissive colorless oxidized state with higher optical contrasts, excellent switching properties. • Obtaining a polymer revealing superior optical contrast in the visible region with fast switching times and high stability.

• Obtaining the paramount candidate material for completion of RGB color space, are aimed.

DESCRIPTION OF THE FIGURES The figures for better explanation of the invention have been prepared and attached to this description. The list of the figures is below.

Scheme 1 - Synthetic route to monomer, DOPEQ

Figure 1 - Repeated potential scan electropolymerization of DOPEQ at 100 mV/s in 0.1 M TBAPFe/DCM/ACN on ITO electrode Figure 3 - Scan rate dependence of PDOPEQ (electrochemically synthesized) film in TBAPFe/ACN (a) 100, (b) 150, (c) 200, (d) 250, (e) 300 mV/s.

Figure 4 - Scan rate dependence of PDOPEQ (chemically synthesized) film, spray-coated on ITO, in TBAPFe/ACN (a) 100, (b) 150, (c) 200, (d) 250, (e) 300 mV/s.

Figure 5 - Colors of PDOPEQ film on an ITO coated glass slide at neutral and oxidized states and spectroelectrochemistry of PDOPEQ film on an ITO coated glass slide in monomer-free, 0.1 M TBAPF₆ /ACN electrolyte-solvent couple at applied potentials; (a) -0.6, (b) -0.15, (c) 0 (d) 0.05, (e) 0.075, (f) 0.1 (g) 0.15, (h) 0.175, (i) 0.2, G) 0.225, (k) 0.25, (1) 0.275, (m) 0.3, (n) 0.35, (o) 0.4, (p) 0.45, (q)0.5, (r) 0.55, (s) 0.6, (t) 0.65, (u) 0.7, (v) 0.8 V Figure 6 - Colors of chemically synthesized PDOPEQ that spray-coated on an ITO coated glass slide at neutral and oxidized states and spectroelectrochemistry of PDOPEQ film on an ITO coated glass slide in monomer-free, 0.1 M TBAPF₆ZACN electrolyte-solvent couple at applied potentials; (a) -0.5, (b) 0.25, (c) 0.3, (d) 0.35, (e) 0.4, (f) 0.45, (g) 0.5, (h) 0.55, (i) 0.65, 0) 0.75, (k) 0.85, (1)0.95, (m) 1.1, (n) 1.2 V. Figure 7 - Electrochromic switching, optical absorbance change monitored at 415 and 690 nm and 1800 nm for PDOPEQ in 0.1 M TBAPF₆ZACN.

SYNTHESIS OF THE UNIQUE PROCESSABLE GREEN POLYMER WITH A TRANSMISSIVE OXIDIZED STATE The design of the monomer was crucial as the material should be polymerized to give a donor-acceptor type macromolecule since these materials mostly reveal two absorption bands in the visible region and the alkyl substitution is a vital necessity to attain a soluble polymer. (Scheme 1)

Pyrocathecol was alkylated with decylbromide via a common procedure^ and the corresponding compound was subjected to Friedel-Crafts acylation with oxalyl chloride to give 1,2 dione structure¹²⁰¹. In the alkylation step, other kind of bases can also be used for the deprotonation of the diol. Also many solvents that promote SN2 type reaction can be utilized. Any other alkylbromide can be used to attain solubility. The boiling point of the solvent should be high above 60 ⁰C. The reactions of this kind generally require temperatures above 60 ⁰C. During the 1,2 dione synthesis, several methods were tried and the one utilizing CS₂ is shown to be the only convenient method. Friedel-Crafts reactions can also be performed in chlorinated solvents. However for this specific reaction CS₂ is the only choice. Bromination of benzothiadiazole was performed in a mixture of HBrZBr₂ to give the dibrominated compound in very high yields^[21J. The addition temperature should be between 10 and 25 C. HBr should be 28- 48% as the solvent and the reagent for the reaction. Subsequent reduction of the compound was achieved using excess amount of NaBH₄ ¹²²¹. NaBH₄ reduction is convenient. Many other reducing agents such as LiAlH₄ can be used. More powerful reducing agents can either react with the solvent or cleave bromine substituents of the reactant. The solvent can be any alcohol or ether. The temperature should be around zero or lower during the addition of the reducing agent. A simple condensation reaction was performed in ethanol with the dibromo diamino compound and alkylated 1,2 dione to give the corresponding dibromoquinoxaline ^[23]. Acetic acid or chloroform can also be used as the solvents for the condensation reaction. The condensation reaction can also be performed by same reagent but in acetic acid reflux for 24 hours or chloroform reflux in 12 hours. Stannylation of EDOT was achieved by addition of equimolar strong base, n-BuLi followed by the addition of Bu₃SnCl^[24]. The reaction was performed in THF but other solvents like diethylether can also be utilized. Lastly a convenient method for the formation of carbon-carbon bond; Stille coupling was used to attach donor EDOT moieties to the acceptor quinoxaline unit to give the title compound 2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-bis(2,3-dihydrothieno[3,4-b][l ,4]dioxin- 5-yl)quinoxaline (DOPEQ) in satisfactory yields. In this step, 2,3-bis(3,4- bis(decyloxy)phenyl)-5,8-dibromoquinoxaline (200 mg, 0.188 mmol) and tributyl (2,3- dihydrothieno[3,4-b][l,4]dioxin-5-yl)stannane (405 mg , 0.939 mmol) were dissolved in dry THF (100 ml) and the solution was purged with argon for 30 min. PdCl₂(PPh₃)₂ (35 mg, 0.05 mmol) was added at room temperature under argon atmosphere. The mixture was stirred at 90-150 C under argon atmosphere for 12-24 hours, cooled and concentrated on the rotary evaporator. The residue was subjected to column chromatography to afford an orange solid (145 mg, 65 %). In the last step, 1:5 mole ratio between the dibromo compound and the stannyl derivative should be attained in order to prevent mono coupling reaction. Higher ratios can also be performed. THF reflux is not enough for the completion of the coupling reaction. It should be heated to higher temperatures. Higher boiling solvents can also be used to decrease the reaction times. The best yields are attained by the conditions indicated above. This reaction can be performed with a variety of Pd catalyst in a variety of solvents like dioxane, DMF in addition to THF. The Pd catalyst may be palladium(II)acetate, Tetrakis(triphenylphosphine)palladium(0), Bis(triphenylphosphine)palladium(II) acetate, Bis(dibenzylideneacetone)palladium, Tris(dibenzylideneacetone)dipalladium(0) or Tris(dibenzylideneacetone)dipalladium-chloroform adduct. Other methods like Suzuki coupling can also be applied if boronic acid derivatives are available. In the present invention, other donor-acceptor type polymers can also yield the properties that are described above. Many of these derivatives were synthesized by the inventors and shown to be potential green polymeric materials in their neutral states. These cover;

Any aromatic or aliphatic side chains (having functional groups on them or not) that can be substituted on the 2 and 3 positions of the center quinoxaline unit.

Any functional group can be inserted on the aromatic rings 3,4-ethylenedioxythiophene groups that attached to quinoxaline units have any aromatic or aliphatic substituents on their CH2 bridges, (where R is any aromatic or aliphatic group. These basically cover all of the groups that can be inserted in the main frame of the molecule. Nitrogen, Sulfur, Oxygen containing groups and groups with other atoms on their functionality are covered)

The number of the CH2 groups on the bridges of ethylenedioxythiophene units many vary from 2 to higher numbers. (Eg. Propylenedioxythiophene (3 CH2 units), Butylenedioxythiophene (4 CH2 units)

X : 1,2,3....

The open 6 and 7 positions of the quinoxaline unit can be substituted with any aromatic of aliphatic groups.

CHEMICAL AND ELECTROCHEMICAL POLYMERIZATION

The polymerization via both electrochemical and chemical methods gave neutral state green polymer. 10^"2 M solution of DOPEQ was prepared in a mixture of dichloromethane (DCM) and acetonitrile (ACN) (5/95, v/v) due to the high solubility of the polymer in DCM. Repeated scan electropolymerization of DOPEQ was illustrated in Fig. 1.

Following the monomer oxidation at 0.8 V, an electroactive polymer film quickly grows on the indium tin oxide (ITO) coated glass slides revealing an oxidation potential of 0.5 V and a reduction potential of 0.07 V.

A conventional chemical polymerization was achieved with FeCl₃ in chloroform: Polymerization can be performed with several other methods. Bromination of the monomer can be performed and resulting material can be polymerized by Nickel catalyst. In addition, coupling based polymerization like Stille or Suzuki reactions can also be applied however, the resultant polymer will be slightly different. These polymers can also be neutral state green polymeric materials. For the FeCl₃ procedure, the oxidized polymer was repeatedly washed with methanol, dissolved in THF and completely reduced with 50 % aqueous solution of hydrazine. THF was evaporated and the polymer was extracted with chloroform. The residue was than precipitated with methanol and dried under vacuum to yield the reduced green polymer in high yields. The polymer was dissolved in chloroform and spray-coated on ITO glass slides to investigate its electrochemical and electrochromic properties. Cyclic voltammetry studies revealed that the polymer was oxidized and reduced at the same potentials with that of the electrochemically produced polymer (Fig. 2).

SCAN-RATE DEPENDENCE AND STABILITY A direct relation between the current response and scan rate was perceived for both electrochemically and chemically produced PDOPEQ which directly proves that the films were well-adhered; the electrochemical processes are not diffusion limited and quasi- reversible even at high scan rates^[25] (Fig. 3 and 4).

The polymer film was coated potentiodynamically on ITO as described previously and cycled for 5000 cycles in PC (propylene carbonate / LiClO₄) to investigate the robustness of the polymer versus redox cycling. The polymer revealed tremendous stability since 90 % of the electroactivity remains intact even after 5000 cycles.

SPECTROELECTROCHEMISTRY

Spectroelectrochemistry studies were achieved to probe the optical changes upon doping and dedoping processes. Fig. 5 reveals spectroelectrochemistry and the corresponding colors of electrochemically prepared PDOPEQ at the reduced state and upon doping. PDOPEQ films revealed two absorption bands, as expected from a donor-acceptor type polymer, centered at 415 nm and 690 nm. Although two absorption bands are necessary to obtain a green color, maximum absorption points are also crucial. Absorptions around 400 nm and 700 mm are excellent absorption maxima to yield a saturated green color in the reduced state.

Besides, 41 % and 46 % transmittance differences were calculated with respect to a valley obtained at 500 nm which are the highest ones reported up to date for a processable green electrochromic polymer¹¹¹¹. Upon doping nearly all absorptions in the visible region deplete leaving a tail around 380 nm where a highly transparent oxidized state was obtained. Spectroelectrochemistry study was also performed for the chemically produced and spray coated polymer films as seen in Fig 6. The corresponding spectroelectrochemical series and Y,x,y values are almost identical to those of electrochemically produced polymer. These properties make this material the only processable neutral state green polymer (Y: 443 x: 0.270 y: 0.400) with a transmissive oxidized state (Y: 626 x: 0.314 y: 0.348). This will enable the commercial use of polymer electrochromic based display devices.

The electronic band-gap of the polymer was calculated as 1.45 eV for PDOPEQ, a relatively high band gap keeping in mind that, polymers with donor-acceptor units exhibit band-gaps between 0.9 eV to 1.3 eV in general.¹⁵'²⁶ KINETIC STUDIES

Optical contrasts, switching times and the stabilities of the polymer films upon electrochromic switching between the neutral and oxidized states were investigated in both visible and near-IR regions. The optical contrasts of the PDOPEQ films were calculated to be 29 %, 42 % and 90 % at 415 nm, 690 nm and 1800 nm respectively. Polymer achieves 95 % of these optical contrasts in less than 1 second in the visible region (Fig. 7). Besides, PDOPEQ realizes an outstanding optical contrast of 90 % in NIR region only in 2 seconds. These results are far better than the first example of the processable green polymeric material¹¹¹¹. EXPERIMENTAL

General: AU chemicals were purchased from Aldrich except for anhydrous tetrahydrofuran (THF) which was purchased from Acros. 4,7-Dibromobenzo[l,2,5]thiadiazole [21], 3,6-dibromo-l,2-phenylenediamine[22], l,2-bis(decyloxy)benzene[20], l,2-bis(3,4- bis(decyloxy)phenyl)ethane-l,2-dione[20], tributyl(2,3-dihydrothieno[3,4-b][l,4]dioxin-5- yl)stannane[24] were synthesized according to previously described methods. All reactions were performed under argon atmosphere unless indicated. Acetonitrile (ACN) was dried and distilled over calcium chloride under nitrogen. Polymer film syntheses were accomplished with a Voltalab 50 potentiostat. Electropolymerizations were performed in a three-electrode cell consisting of platinum button or Indium Tin Oxide (ITO) coated glass as the working, platinum wire as the counter electrode, and Ag wire as the pseudo reference electrodes. The electrolyte used was 0.1 M of tetrabutylammonium hexafluorophosphate (TBAPF₆) in dichloromethane. Electrodeposition was performed from a 0.1 M solution of TBAPF₆ at a scan rate 100 mV/s for 30 cycles. Cyclic voltammograms of the polymers were obtained using the same electrode setup in a monomer-free solution. TBAPF^ was used as the electrolyte in ACN. UV-Vis-NIR spectra were recorded on a Varian Cary 5000 spectrophotometer at a scan rate of 2000 nm/min. A three-electrode cell was utilized consisting of a silver wire reference electrode, a Pt wire counter electrode, and an ITO coated glass working electrode. The potentials were controlled by Solartron 1285 potentiostat/ galvanostat. Colorimetry measurements were achieved by a Minolta CS-IOOA Chroma Meter with a 0/0 (normal/normal) viewing geometry as recommended by CIE. ¹H-NMR and ¹³C- NMR spectra were recorded with a Bruker Spectrospin Avance DPX-400 Spectrometer at 400 MHz and chemical shifts (δ) were given relative to tetramethylsilane as the internal standard. Molecular weight of the polymer was determined on Polymer Laboratories PL-GPC 200. Mass analysis was performed on TOF Bruker Mass Spectrometer with an electron impact ionization source.

Monomer Synthesis: 2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-dibromoquinoxaline : A solution of 3,6- dibrorno-l,2-phenylenediarnine (1.0 g, 3.8 mmol) and l,2-bis(3,4- bis(decyloxy)phenyl)ethane-l,2-dione (3.173 g, 3.8 mmol) in ethanol (40 ml) was refluxed overnight with a catalytic amount of PTSA. The mixture was cooled to 0 ⁰C. The precipitate was isolated by filtration and washed with ethanol several times to afford the desired compound. (3.2 g, 79 %). ¹H-NMR (400 MHz, CDCl₃): (ppm) δ 0.8 (t, J = 3.3 Hz, 12 H), 1.1- 1.4 (m, 56 H), 1.65 (m, 4 H), 1.74 (m, 4 H), 3.78 (t, J = 6.5 Hz, 4 H), 3.93 (t, J = 6.5 Hz, 4 H), 6.76 (d, 2 H, J = 8.1 Hz), 7.18 (s, 2 H), 7.21 (d, 2 H, J = 8.8 Hz), 7.74 (s, 2 H). ¹³C-NMR (100 MHz, CDCl₃): δ (ppm) 14.10, 22.70, 26.05, 29.14, 29.24, 39.36, 29.40, 29.45, 29.61, 29.64, 29.71, 31.94, 69.17, 69.25, 113.04, 115.70, 123.44, 130.62, 132.52, 138.98, 148.74, 150.70, 153.62.

2, 3-bis(3, 4-bis(decyloxy)phenyl)-5, 8-bis(2, 3-dihydrothieno[3, 4-b][l, 4]dioxin- 5yl)quinoxaline(DOPEQ): 2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-dibromoquinoxaline (200 mg, 0.188 mmol) and tributyl (2,3-dihydrothieno[3,4-b][l,4]dioxin-5-yl)stannane (405 mg , 0.939 mmol) were dissolved in dry THF (100 ml), the solution was purged with argon for 30 min. and PdCl₂(PPh₃)₂ (35 mg, 0.05 mmol) was added at room temperature under argon atmosphere. The mixture was stirred at 100 ⁰C under argon atmosphere for 15 hours, cooled and concentrated on the rotary evaporator. The residue was subjected to column chromatography to afford an orange solid (145 mg, 65 %). ¹H-NMR (400 MHz, CDCl₃): δ (ppm) 0.80 (t, J = 3.3 Hz, 12 H), 1.1-1.4 (m, 56 H), 1,6-1.8 (m, 8 H), 3.85 ( t, J = 6.5 Hz, 4 H), 3.93 (t, J = 6.5 Hz, 4 H), 4.19 (m, 4 H), 4.28 (m , 4 H), 6.41 (s, 2 H), 6.74 (d , 2 H , J = 8.4 Hz), 7.19 (d, 2 H , J = 8.4 Hz), 7.39 (s , 2 H), 8.49 (s, 2 H). ¹³C-NMR (100 MHz, CDCl₃): δ (ppm) 13.08, 21.67, 25.06, 25.09, 28.21, 28.23, 28.34, 28.38, 28.45, 28.58, 28.61, 28.63, 28.70, 30.91, 63.33, 63.93, 68.13, 68. 22, 101.67, 111.83, 112.46, 115.08, 122.58, 126.60, 127.39, 130.40, 135.73, 139.24, 140.42, 147.66, 148.92, 149.24 , MS: m/e 1088 (M⁺-H). Polymer Synthesis: The reaction was performed following the literature procedures.

100 mg DOPEQ was dissolved in 2 ml of dry CHCl₃ under argon atmosphere. 75 mg FeCl₃ was suspended in 2 ml CHCl₃ and slowly added to monomer solution. The reaction mixture was stirred for 2 hours and the mixture was added to 200 ml of methanol. The precipitates were collected, dissolved in CHCl₃ and repeatedly extracted with water. The chloroform extracts were combined and evaporated under reduced pressure. The residue was dissolved in 50 ml THF and 50 ml hydrazine was added. The mixture was stirred for 24 hours for complete dedoping process. A deep green solution was obtained and the THF was evaporated under reduced pressure. Chloroform was added to residue and the organic phase was extracted several times with water. Combined organic phases were evaporated and the residue was washed with acetone several times to remove the unreacted monomer. Polymer was then dried under vacuum to give the title compound in high yields. NMR results revealed that polymerization was achieved as given by the broadening of the peaks and a decrease of the signal at δ 6.41 ppm which corresponds to the hydrogen resonance of the terminal EDOT units.

¹H-NMR (400 MHz, CDCl₃): δ (ppm) 0.8 (-CH₃), 1.1-1.4 (-CH₂), 1.5-17 (-0-CH₂-CH₂), 3.5- 3.8 (-0-CH₂), 3.8-4.4 (-0-CH₂-CH₂-O-), 6.88 (pendant phenyl rings), 7.23 (pendant phenyl rings), 7.48 (pendant phenyl rings), 8.58 (quinoxaline)

FT-IR: 996 cm^"1 (m); 1074 cm^"1 (m); 1188 cm^"1 (m); 1261 cm^"1 (m); 1392cm^'1 (m); 1631 cm^"1 (s); 2854 cm^"1 (w); 2924 cm^"1 (m).

GPC : M_n : 31800, M_w: 110028, HI: 3.46

CONCLUSIONS

As a conclusion, PDOPEQ films revealed a saturated green color in the neutral and a high transmitivity in the oxidized state; with outstanding optical contrasts both in the visible and NIR region, very fast switching times, high stability and excellent solubility in all common organic solvents. Putting these together, PDOPEQ is a paramount choice for the potential realization of RBG based polymer electrochromic device applications.

Claims

CLAIMS - The synthesis of a unique processable green polymer with a transmissive oxidized state characterized in that; a) obtaining 2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-dibromoquinoxaline by performing,

• After alkylation of pyrocathecol with decylbromide, subjecting the corresponding compound to Friedel-Crafts acylation with oxalyl chloride to give 1 ,2 dione structure.; in the alkylation step, other kind of bases are used for the deprotonation of the diol. Also many solvents that promote SN2 type reaction are utilized, • The boiling point of the solvent is higher than 60 ⁰C,

• During the 1,2 dione synthesis, CS₂ is utilized,

• Performing bromination of benzothiadiazole in a mixture of HBrZBr₂ to give the dibrominated compound in very high yields by temperature addition between 10 and 25 ⁰C and HBr is 28- 48% as the solvent and the reagent for the reaction, • Achieving subsequent reduction of the compound using excess amount OfNaBH₄,

• A simple condensation reaction was performed with the dibromodiamino compound and alkylated 1 ,2 dione to give the corresponding dibromoquinoxaline, with the duration of reaction as 12 to 24 hours, b) obtaining tributyl (2,3-dihydrothieno[3,4-b][l,4]dioxin-5-yl)stannane by performing; • Achieving Stannylation of EDOT by addition of equimolar strong base, n-BuLi followed by the addition OfBu₃SnCl wherein the reaction was performed in THF. c) Using coupling to attach donor EDOT moieties to the acceptor quinoxaline unit to give the title compound 2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-bis(2,3-dihydrothieno[3,4- b] [ 1 ,4]dioxin-5-yl)quinoxaline (DOPEQ)

DOPEQ in satisfactory yields by performing;

• In this step, 2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-dibromoquinoxaline (200 mg, 0.188 mmol) and tributyl (2,3-dihydrothieno[3,4-b][l,4]dioxin-5-yl)stannane (405 mg , 0.939 mmol) were dissolved in dry THF (100 ml) and the solution was purged with argon.

• Pd catalyst (35 mg, 0.05 mmol) was added at room temperature under argon atmosphere.

• The mixture was stirred at 90-150 ⁰C under argon atmosphere for 12-24 hours, cooled and concentrated on the rotary evaporator, and the residue was subjected to column chromatography to afford an orange solid (145 mg, 65 %). d) Using either electrochemical or chemical methods to get neutral state green polymer poly(2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-bis(2,3-dihydrothieno[3,4-b][l,4]dioxin-5- yl)quinoxaline) (PDOPEQ). 2- According to the Claim 1, in the step (a), in achieving subsequent reduction of the compound, LiAlH₄ is used instead OfNaBH₄,

3- According to the Claim 1, in the step (a), in achieving subsequent reduction of the compound, the solvent can be any alcohol or ether.

4- According to the Claim 1, in the step (a), in achieving subsequent reduction of the compound, the temperature is around zero or lower during the addition of the reducing agent.

5- According to Claim 1, in the step (a), in simple condensation reaction, acetic acid or chloroform can be used as the solvents for the condensation reaction. 6- According to Claim 1 , in the step (a), in simple condensation reaction, the reaction is also performed by same reagent but in acetic acid reflux for 24 hours or chloroform reflux in 12 hours.

7- According to Claim 1, in the step (b), in achieving stannylation of EDOT by addition of equimolar strong base, n-BuLi followed by the addition of Bu₃SnCl wherein the reaction may be performed in diethylether instead of THF.

8- According to Claim 1, in the step (c), higher ratios between the dibromo compound and the stannyl derivative may be attained instead of 1 :5 mole ratio.

9- According to Claim 1, in the step (c), dioxane or DMF is used instead of THF. 10- According to Claim 1 , in the step (c), Pd catalyst is PdCl₂(PPh₃)₂

11- According to Claim 1, in the step (c), the reaction is performed with Palladium(II)acetate, Tetrakis(triphenylphosphine)palladium(0), Bis(triphenylphosphine)palladium(II) acetate, Bis(dibenzylideneacetone)palladium, Tris(dibenzylideneacetone)dipalladium(0) or Tris(dibenzylideneacetone)dipalladium-chloroform adduct as Pd catalyst. 12- According to Claim 1, in the step (c), Suzuki coupling method is also applied if boronic acid derivatives are available.

13- According to Claim 1, in the step (d), in electrochemical method, 10^"2 M solution of

DOPEQ is prepared in a mixture of dichloromethane (DCM) and acetonitrile (ACN) (5/95, v/v) and repeated scan electropolymerization is performed between -0.7 to 1.1 V using DOPEQ (Fig. 1)

14- According to Claim 1, in the step (d), in the chemical method,

• A conventional chemical polymerization is achieved with FeCl₃ in chloroform,

• in this FeCl₃ procedure, the oxidized polymer is repeatedly washed with methanol, dissolved in THF and completely reduced with 50 % aqueous solution of hydrazine, • THF is evaporated and the polymer is extracted with chloroform.

• The residue is than precipitated with methanol and dried under vacuum to yield the reduced green polymer in high yields

15- According to Claim 1, in the step (d), in the chemical method, instead OfFeCl₃ the polymerization is performed using nickel catalyst. - According to Claim 1, in the step (d), in the chemical method, instead of oxidation procedure with FeCl₃, coupling based polymerization like Stille or Suzuki reactions is also applied . - The polymer poly(2,3-bis(3,4-bis(decyloxy)phenyl)-5,8-bis(2,3-dihydrothieno[3,4- b][l,4]dioxin-5-yl)quinoxaline (PDOPEQ) is produced according to the method in any of the preceding claims. - According to Claim 1, in step (c); any aromatic or aliphatic side chains having functional groups on them or not, that can be substituted on the 2 and 3 positions of the center quinoxaline unit.

9- According to Claim 1, in step (c); any functional group can be inserted on the aromatic rings. 0- According to Claim 1, in step (c); 3,4-ethylenedioxythiophene groups attached to quinoxaline units have any aromatic or aliphatic substituents on their CH₂ bridges, where R is any aromatic or aliphatic group.

- According to Claim 1, in step (c); the number of the CH₂ groups on the bridges of ethylenedioxythiophene units many vary from 2 to higher numbers.

X : 1,2,3.... - According to Claim 1, in step (c); the open 6 and 7 positions of the quinoxaline unit can be substituted with any aromatic or aliphatic groups.