<Emphasis Type="Italic">Tetra</Emphasis>-EDOT substituted 3D electrochromic polymers with lower band gaps

A couple of novel electrochromic materials poly(2,3,4,5-tetrakis(2,3-hydrothieno[3,4-b]dixin-5-yl)-1-methyl-1H-pyrrole) (P(t-EDOT-mPy)) and poly(5,5′,5′′,5′′′-(thiophene-2,3,4,5-tetrayl)tetrakis(2,3-dihydrothieno[3,4-b][1,4]dioxine)) (P(t-EDOT-Th)) are electrodeposited via multi-position polymerization of their tetra-EDOT substituted monomers t-EDOT-mPy and t-EDOT-Th, respectively. Compared with the linear 2D structured poly(thiophene) (E _g=2.2 eV) and poly(2,5-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)thiophene) (E _g=1.7 eV), P(t-EDOT-Th) (E _g=1.62 eV) has the lowest band gap. Hence, we speculate that the band gaps of the two polymers, having 3D structures, are decreased in contrast to non-substituted polymers or bi-EDOT substituted polymers, thiophene and 1-methyl-1H-pyrrole. The results indicated that P(t-EDOT-Th) thin films are more stable and show higher transmittance amid two polymers, which may find their utilization in organic optoelectronics.     

Blue-to-transmissive electrochromic poly(2,3-dimethyl-2,3-dihydrothieno[3,4-b][1,4]dioxine) (PEDOT-Me2) with improved optical contrast

Journal of Solid State Electrochemistry - A novel electrochromic polymer poly(2,3-dimethyl-2,3-dihydrothieno[3,4-b][1,4]dioxine) (PEDOT-Me2) based on 3,4-ethylenedioxythiophene (EDOT) with...     

[1,2,5]thiadiazolo[3,4‐g]quinoxaline acceptor‐based donor–acceptor–donor‐type polymers: Effect of strength and size of donors on the band gap

Electrochromic polymers based on [1,2,5]thiadiazolo[3,4‐g]quinoxaline acceptor and thiophene, 3,4‐ethylenedioxythiophene and 3,3‐didecyl‐3,4‐proylenedioxythiophene donors, namely poly(6,7‐diphenyl‐4,9‐di(thiophen‐2‐yl)‐[1,2,5]thiadiazolo[3,4‐g]quinoxaline) ( P1 ), poly(4‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐5‐yl)‐9‐(2,3‐dihydrothieno[3,4‐b][1,4]dioxin‐7‐yl)‐6,7‐diphenyl‐[1,2,5]thiadiazolo[3,4‐g]quinoxaline) ( P2 ), and poly(4‐(3,3‐didecyl‐3,4‐dihydro‐2H‐thieno[3,4‐b][1,4]dioxepin‐6‐yl)‐9‐(3,3‐didecyl‐3,4‐dihydro‐2H‐thieno[3,4‐b][1,4]dioxepin‐8‐yl)‐6,7‐diphenyl‐[1,2,5]thiadiazolo[3,4‐g]quinoxaline) ( P3 ), respectively, were electrochemically and/or chemically synthesized and characterized. Electrochemical and optical properties of the polymers were then investigated. The results, which were obtained electrochemically and optically, indicate that the polymers bearing the same acceptor and different donor units have a band gap range of 0.59–1.24 eV depending on the strength and size of the donor units and band gap determination method. A significant finding in this study was the phenomenon that when the acceptor is physically huge, the general rule that a weak donor would have a high band gap whereas a strong donor would have low band gap can be broken due to the torsional angles/steric hindrances involved with physically large donor molecules. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3483–3493     

Decyloxyphenyl-substituted quinoxaline-embedded conjugated electrochromic polymers with high switching stability and fast response speed

Two novel decyloxyphenylquinoxaline-based donor-acceptor(D-A) electroactive monomers bearing dialkoxythiophene as the donor unit are synthesized using Stille coupling reaction. The corresponding polymers, poly[2,3-bis(4-decyloxyphenyl)-5,8-bis(3,4-dimethoxylthiophen-2-yl)quinoxaline](P1) and poly[2,3-bis(4-decyloxyphenyl)-5,8-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)quinoxaline](P2), are directly deposited onto the working electrode surface by electropolymerization. All materials were characterized by nuclear magnetic resonance(NMR), mass spectrometry(MS), scanning electron microscopy(SEM), cyclic voltammetry(CV), ultraviolet-visible absorption spectrometry(UV-Vis) and spectro-electrochemical measurements. Electrochemical studies demonstrate that both polymers are capable of showing both reasonable n- and p-doping processes, and advanced long-term switching stabilities. 3,4-Ethylenedioxythiophene substituted for 3,4-dimethoxythiophene as a donor unit, which enhances the conjugated double-bond character of the conducting polymer, thus leading to a lower electronic band-gap. Likewise, the neutral state color of the synthesized polymer tuned from blue to blue-green corresponding to the red shift of the maximum absorption wavelengths in the visible region. In addition, kinetics study of P1 revealed 42%(595 nm), 30%(839 nm) and 69%(1500 nm) transmittance changes(ΔT%), while P2 exhibited 32%(740 nm), 71%(2000 nm) at the dominant wavelengths. It was also observed that both films could switch quickly between the neutral state and oxidation state, with the response time less than 1 s both in visible and near infrared regions.     

Facile synthesis of some novel pyrido[3',2':4,5]thieno[2,3-b][1,4]thiazine-8-carboxylic acids

Model tetrahydropyrido[3',2':4,5]thieno[2,3-b][1,4]thiazines 9a-c were synthesized via reductive lactamization, using sodium dithionite, of the respective 2-[(carboxyalkyl)thio]-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acids 7a-c. The latter derivatives were made via interaction of 2-chloro-7-cyclopropyl-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acid (6) with each of alpha-mercaptoacetic, alpha-mercaptopropionic, and alpha-mercaptosuccinic acids and triethylamine in aqueous acetone at room temperature. The structures of 7a-7c and 9a-9c are supported by microanalytical and spectral (IR, MS, NMR) data. Compounds 9a and 9c showed potent inhibitory activity against the IGROV1 (Ovarian Cancer) cell line.     

Syntheses and Optical Properties of Perfluorophenyl Containing Benzimidazole Derivatives: The Effect of Donor Units

Synthesis of two novel donor – acceptor – donor type monomers containing benzimidazole as the acceptor unit and thiophene and 3,4-ethylenedioxythiophene (EDOT) as the donor units were performed. 2-(Perfluorophenyl)-4,7-di(thiophen-2-yl)-1H-benzo[d]imidazole and 4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2-(perfluorophenyl)-1H-benzo[d]imidazole were synthesized successfully and polymerized electrochemically. The electrochemical and spectroelectrochemical studies of the polymers were studied. The effect of electron donating moieties on the optical properties of electrochemically polymerized polymers was investigated. Both polymers were p type dopable and possessed multi-chromic property. Optical studies demonstrated that the polymer based on EDOT unit (P2) resulted in lower band gap since EDOT is higher electron donating group than thiophene.     

Chiral ethylhexyl substituents for optically active aggregates of pi-conjugated polymers

We report an efficient synthesis of chiral (2S)-ethylhexanol for functionalizing and solubilizing conjugated polymers. The alpha-substituted chiral ethylhexyl side chains were obtained through a powerful and flexible asymmetric synthesis using pseudoephedrine as a chiral auxiliary. The dependence of the properties of conjugated polymers on molecular structure is investigated by circular dichroism, fluorescence, and absorption spectroscopy on two new chiral conjugated polymers, poly(3,3-bis((S)-2-ethylhexyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine) (PProDOT((2S)-ethylhexyl)(2)) and poly(3,3-bis((S)-2-methylbutyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine) (PProDOT((2S)-methylbutyl)(2)). The properties of PProDOT((2S)-ethylhexyl)(2)) differ significantly from those of its methylbutyl analog as investigated by chiral aggregation providing insight into the role of interchain interactions in these subsecond switching electrochromic polymers.     

Novel One-Pot Multicomponent Synthesis of Substituted 2,3-Dihydro-2-(6-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-3-yl)phthalazine-1,4-diones and Substituted 3-[3-(N′-Benzylidene-hydrazino)-7H-[1,2,4] triazolo[3,4-b][1,3,4]thiadiazin-6-yl]-4-hydroxy-6-methyl-pyran-2-ones

A one-pot procedure has been developed for the synthesis of substituted 2,3-dihydro-2-(6-(4-hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7H-[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazin-3-yl)phthalazine-1,4-diones by reaction of 3-(2-bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one, 4-amino-5-hydrazino-4H-[1,2,4]triazole-3-thiol, and phthalic anhydrides in acetic acid medium. Similarly, a one-pot, three-component synthetic procedure has been developed for substituted 3-[3-(N¹-benzylidene-hydrazino)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazin-6-yl]-4-hydroxy-6-methyl-pyran-2-ones from 3-(2-bromoacetyl)-4-hydroxy-6-methyl-2H-pyran-2-one, 4-amino-5-hydrazino-4H-[1,2,4]triazole-3-thiol, and various aromatic aldehydes in absolute ethanol and a few drops of glacial acetic acid.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Synthesis of 3-amino-6-methyl-5-ethoxycarbonyl-4,7-dihydrothieno[2,3-b]pyridine derivatives

The alkylation of piperidinium salts of substituted 1,4-dihydropyridine-2-thiols with chloroacetonitrile or iodoacetamide gave 2-cyanomethylthio- and 2-carbamoylmethylthio-substituted 6-methyl-4-aryl(pyridyl)-5-ethoxycarbonyl-3-cyano-1,4-dihydropyridines, which undergo intramolecular cyclization in basic media to give 3-amino-6-methyl-4-aryl(pyridyl)-5-ethoxycarbonyl-2-cyano(carbamoyl)-4,7-dihydrothieno[2,3-b]pyridines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 124–128, January, 1987.     

Thiadiazoloquinoxaline and benzodithiophene bearing polymers for electrochromic and organic photovoltaic applications

Abstract

Two novel thiadiazoloquinoxaline and benzodithiophene (BDT) bearing copolymers were designed and synthesized. Different BDT units (alkoxy and thiophene substituted) were used as donor materials and the effect of alkoxy and thiophene substitution on the electrochemical, spectroelectrochemical and photovoltaic properties were investigated. Both polymers exhibited low oxidation potentials at around 0.90 V and low optical band gaps at around 1.00?eV due to the insertion of electron poor thiadiazoloquinoxaline unit into the polymer backbone. Both P1 (poly-6,7-bis(3,4-bis(decyloxy)phenyl)-4-(4,8-bis(nonan-3-yloxy)benzo[1,2-b:4,5-b']dithiophen-2-yl)-[1, 2, 5]thiadiazolo[3,4-g]quinoxaline) and P2 (poly- 4-(4,8-bis(5-(nonan-3-yl)thiophen-2-yl)benzo[1,2-b:4,5-b']dithiophen-2-yl)-6,7-bis(3,4-bis(decyloxy)phenyl)-[1, 2, 5]thiadiazolo[3,4-g]quinoxaline) exhibited multichromic behavior with different tones of greenish yellow and gray in the neutral and fully oxidized states, respectively. In addition, both polymers revealed very high optical contrasts (～87%) in the NIR region which make these promising polymers good candidates for NIR applications. Finally, in order to explore the organic photovoltaic performances, P1 and P2 were mixed with PC₇₁BM in the active layer of organic solar cells (OSCs) by conventional device structure. As a result P1 and P2 based devices revealed power conversion efficiencies (PCEs) of 0.33% and 0.60% respectively. However, the additive treatment enhanced PCE from 0.49 to 0.73% for P2 based devices.     

Synthesis and Biological Evaluation of Some Novel N,N ′-Bis-(1,2,4-Triazin-4-Yl)Dicarboxylic Acid Amides and Some Fused Rings with 1,2,4-Triazine Ring

Some of novel N , N '-bis-(1,2,4-triazin-4-yl)dicarboxylic acid amides ( 2-5 ) and thiadiazolo[2,3- b ][1,2,4]triazin-7-yl carboxylic acid derivatives ( 6 , 7 ) were prepared by heating 4-amino-6-methyl-5-oxo-3-thioxo-2,3,4,5-tetrahydro-1,2,4-triazine ( 1 ) with different dicarboxylic acids (oxalic, malonic, fumaric, maleic, succinic, and phthalic acids respectively) in POCl 3 . Refluxing 1 with 1-chloro-2,4-dinitrobenzene in DMF yielded 3-methyl-6-nitro-10 H -benzo[1,2,4]thiadiazino[2,3- c ][1,2,4]triazin-4-one ( 8 ). Condensation of 1 with 2,4-pentandione in refluxing acetic acid furnished 6-methyl-4-(1-methyl-3-oxobut-1-enylamino)-3-thioxo-3,4-dihydro-2 H -[1,2,4]triazin-5-one ( 9 ). 3,8-D imethyl[1,2,4] triazino[3,4- b ][1,3,4]thiadiazine-4,7-dione ( 11 ) was prepared by refluxing 1 with 2-bromopropionyl bromide in anhydrous benzene to afford the corresponding N -acetylated derivative 10 , which was cyclized by using triethylamine. Also, some triazinylquinazolinones 13a , b were obtained by fusion of 1 with 6-bromo(and/or 6,8-dibromo)-2-methyl-3,1-benzoxazin-4 H -ones.     

Reactions of some new thienothiophene derivatives

Facile and convenient syntheses of bisdimethylthieno[2,3-b]thiophen-2,5-diyl bis(oxazole-2-amine), bis(1H-imidazol-2-amine), bis((3a)-H-indole),[1,2-a]pyrimidine), bis(1H-imidazo[1,2-b][1,2,4]triazole) and bis(9H-benzo[d]imidazo[1,2-a]imidazole) derivatives incorporating a thieno[2,3-b]thiophene moiety from the versatile and readily accessible 1,1'(3,4-dimethylthieno[2,3-b]thiophene-2,5-diyl)-bis(2-bromo-ethanone) (1) are described.     

Bromination and diazo-coupling of pyridinethiones; microwave assisted synthesis of isothiazolopyridine, pyridothiazine and pyridothiazepines

Isothiazolopyridines, pyridothiazines and pyridothiazepines are important compounds that possess valuable biological activities. This paper reports on the synthesis of these compounds using both conventional chemical methods and modern microwave techniques. 3-Bromo-6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide, 5-arylazo-6-hydroxy-4-methyl-2-thioxo-1,2-dihydropyridine-3-carboxamides, 3,5-bis-arylazo-6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-caboxamide, 4-methyl-2,3,6,7-tetra-hydroisothiazolo[5,4-b]-pyridine-3,6-dione, 2,2'-(methylene-bis-(sulfanediyl))bis(4-methyl-6-oxo-1,6-dihydropyridine-3-carboxamide), 2-hydroxy-5-methyl-4H-pyrido[3,2-e][1,3]-thiazine-4,7(8H)-dione and 2-arylmethylene-8-hydroxy-6-methyl-2,3,4,5-tetrahydropyrido-[3,2-f][1,4]thiazepine-3,5-diones have been prepared from 6-hydroxy-4-methyl-2-thioxo-2,3-dihydropyridine-3-carboxamide. Some of these compounds were prepared using microwave-assisted reaction conditions, that provided higher yields in shorter times than the conventional methods.     

4H-dithieno[2,3-b:3',2'-e][1,4]thiazines--synthesis and electronic properties of a novel class of electron rich redox systems

Quantum chemical screening reveals that 4H-dithieno[2,3-b:3',2'-e][1,4]thiazines possess the highest HOMO among four constitutional isomers, even 0.27 eV higher in energy than the well established 10H-phenothiazine. N-Substituted 4H-dithieno[2,3-b:3',2'-e][1,4]thiazines are readily accessible by twofold Pd-catalyzed amination. According to cyclic voltammetry dithienothiazines are reversibly oxidized and can be considered as new donors for functional π-systems.     

Synthesis of new donor-acceptor polymers containing thiadiazoloquinoxaline and pyrazinoquinoxaline moieties: low-band gap, high optical contrast, and almost black colored materials

Two low band gap conjugated polymers, poly[4,9-bis(4-hexylthien-2-yl)-6,7-di(thien-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline] (PHTTQ) and poly[5,10-bis(4-hexylthien-2-yl)-2,3,7,8-tetra(thien-2-yl)pyrazino[2,3-g]quinoxaline] (PHTPQ), consisting of alternating electron-rich 3-hexylthiophene and electron-deficient 6,7-di(thien-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline (TTQ) and 2,3,7,8-tetra(thien-2-yl)-2,3-dihydropyrazino[2,3-g]quinoxaline (TPQ) units were synthesized electrochemically. The structures of the π-conjugated monomers were tailored using thiophene as the pendant group on the acceptor units (TTQ and TPQ). The electrochemical and optical properties of the polymers were investigated by cyclic voltammetry and UV-vis-NIR spectroscopy. The absorption spectra of PHTPQ, revealing a 1.0 eV band gap, exhibited three maxima at 352 nm, 535 nm, and 750 nm. Consequently, its absorption spectra cover the region between 400 and 800 nm, which make the polymer almost black in appearance. PHTTQ shows a λ_max value of 820 nm and a band gap of 0.8 eV which is very low among other [1,2,5]thiadiazolo[3,4-g]quinoxaline-containing donor-acceptor type polymers.     

Condensed pyridazines. Part III. Rearrangement and ring cyclization during the thermolysis of (z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-methylacrylate

The thermolysis of (Z)-methyl 3-(6-azido-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazin-5-yl)-2-methylacrylate ( II ) provides a new synthetic route to pyrrolo[2,3-c-]pyridazines, specifically, methyl 3-chloro-1,6-dimethyl-4-oxo-1,4-dihydro-7H-pyrrolo[2,3-c]pyridazine-5-carboxylate ( III ) in 91% yield. Treatment of III with ozone provides an entry into the novel pyridazino[3,4-d][1,3]oxazine ring system, specifically, 3-chloro-1,7-dimethylpyridazino[3,4-d][1,3]oxazine-4,5-dione ( IV ) in 73% yield. Compound IV is smoothly hydrolyzed into 6-acetylamino-3-chloro-1-methyl-4-oxo-1,4-dihydropyridazine-5-carboxylic acid ( V ) which is readily recyclized into IV by dehydration with acetic anhydride. Furthermore, IV undergoes a facile reductive ring opening reaction with sodium borohydride to give 3-chloro-6-ethylamino-1-methyl-4-oxo-1,4-dihydropyridazine-5-carboxylic acid ( VI ) in 95% yield.     

Synthesis of 6-methyl-5-phenylcarbamoyl-3,4-dihydropyridinespiro-4-cyclohexane-2(1H)-thione and its derivatives

3-Cyano-6-methyl-5-phenylcarbamoyl-3,4-dihydropyridinespiro-4-cyclohexane-2(1H)-thione was obtained by the condensation of acetoacetic acid anilide with cyclohexylidenecyanothioacetamide. Substituted 2-alkylthio-1,4-dihydropyridines and 3-amino-2-(4-chlorobenzoyl)-6-methyl-5-phenylcarbamoyl-4,7-dihydrothieno[2,3-b]pyridinespiro-4-cyclohexane were synthesized from it. T. G. Shevchenko Lugansk State Pedagogical Institute, Lugansk 348011, Ukraine N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1533–1535, November, 1997.     

Substituent and heteroatom effects on the electrochromic properties of similar systems

Electrochromic polymers called poly(3,4‐dihydro‐3,3‐bis ((naphthalen‐1‐yl)methyl)‐2H‐thieno[3,4‐b][1,4]dioxepine) (PProDOT‐Np₂), poly(3,3‐dibenzyl‐3,4‐dihydro‐2H‐selenopheno[3,4‐b][1,4]dioxepine), and poly(3,3‐dibenzyl‐3,4‐dihydro‐2H‐thieno[3,4‐b][1,4]dioxepine) were synthesized electrochemically and the effect of substituents and heteroatoms on the electrochromic properties were investigated for the similar systems. All polymers show electrochromism from a colored state when neutralized to transmissive when oxidized. Although, increasing bulky size (PProDOT‐Np₂) causes lower coloration efficiency (CE) as well as lower optical contrast, the replacement of S atom by Se atom resulted in a lower band gap polymer with a higher CE than its thiophene analog. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

A NOVEL SYNTHESIS OF 2-SUBSTITUTED-4H-THIENO [2,3-d][1,3] OXAZIN-4-ONE AND 2,3-DISUBSTITUTED THIENO [2,3-d]PYRIMIDIN-4(3H)-ONE DERIVATIVES

Abstract

The synthesis of acetic 2-{[1-methyl-2-(4-oxo-5,6,7,8-tetrahydro-4H-benzo [4,5]-thieno [2,3-d] [1,3-oxazin-2-yl)ethylidene]amino}-4,5,6,7-tetrahydrohenzo[b]thiophene ?3-carboxylic acid anhydride 5 and 2-(oxopropyl)-5,6,7,8-tetrahydro-4H-benzo-[4,5] thieno[2,3-d][1,3]oxazin-4-one 7, has been achieved in three steps from ethyl 2-amino-4,5,6,7-tetrahydrobenzo(b]thiophene-3-carboxlate 1 via the reaction with ethyl acetoacetate followed by hydrolysis and acetic anhydride-induced cyclization. The 2-substituent in compound 5 has two functional groups i.e. active methylene and acid anhydride which are suitably located for intramolecular transformation. Thermal and/or base catalyzed intramolecular cyclization of 5 afforded 2-(4-acetoxy-(hydroxyl)-2-methyl-5,6,7,8-tetrahydrobenzo[4,5] thieno[2,3-b]pyridin-3-yl)-5,6,7,8- tetrahydro-4H-benzo[4,5]thieno[2,3-d] [1,3]oxazin-4-one 10 and 9 respectively. Treatment of 5 with hydrazine hydrate, aromatic and/or heterocyclic amines induced the same intramolecular cyclization with a concomitant oxazine-pyrimidine interconversion to give 3-amino(aryl or heteryl)-2-(4-hydroxy-5,6,7,8-tetrdhydrobenzo-[4,5]thieno[2,3-b]pyridin-3-yl)-3,4,5,6,7,8-hexahydrobenzo[4,5] thieno[2,3-d] pyrimid in-4-one 11–14 respectively.     

A concise synthesis and electrochemical behavior of functionalized poly(thieno[3,4-b]thiophenes): New conjugated polymers with low bandgap

New thieno[3,4-b]thiophene derivatives were prepared via a short and versatile synthetic route. Electrochemical studies of 2-heptenylthieno[3,4-b]thiophene, 2-styrylthieno[3,4-b]thiophene, and 2-phenyl-3-(thieno[3,4-b]thiophene-2-yl)acrylonitrile and the corresponding polymers revealed that raising the HOMO and lowering the LUMO can be attained by functionalizing thieno[3,4-b]thiophene with aromatic resonance-enhancing and electron-withdrawing groups. The bandgap of resulting polymers varied from 0.78 to 1.0 eV, indicating that poly(2-phenyl-3-(thieno[3,4-b]thiophene-2-yl)acrylonitrile) is one of the lowest bandgap polymers ever reported.