Multichromic benzimidazole‐containing polymers: Comparison of donor and acceptor unit effects

This study reports a comparative study on electrochromic properties of two donor–acceptor–donor (DAD)‐type polymers namely poly(2‐heptyl‐4,7‐di(thiophen‐2‐yl)‐1H‐benzo [d]imidazole) (BImTh) and poly(4,7‐bis(2,3‐dihydrothieno[3,4‐b] [1,4]dioxin‐5‐yl)‐2‐heptyl‐1H‐benzo[d]imidazole) (BImEd). DAD‐type monomers were polymerized electrochemically on indium tin oxide‐coated glass slides to determine the optical properties of the polymers. Electrochemical p‐doping experiments were performed to determine the band gap and absorption band values of the polymer films at different redox states. Polymerization of BImTh and BImEd yields multichromic polymers. Donor and acceptor effects are studied by comparing the PBImEd and PBImTh with corresponding benzotriazole derivatives. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Benzooxadiazaole‐based D–A–D co‐oligomers: Synthesis and electropolymerization

Four D–A–D type co‐oligomers have been synthesized by Stille condensation between monostannyl derivatives of furan/thiophene/selenophene/3,4‐ethylenedioxythiophene (EDOT) and 4,7‐dibromo‐benzo[1,2,5]oxadiazole. All these co‐oligomers were successfully electrochemically polymerized in dichloromethane and characterized by spectroelectrochemistry. All four polymers possess narrow optical band gap. Spectroelectrochemical studies of polymer films on indium tin oxide revealed that the replacement of donor EDOT with furan/thiophene/selenophene has affected the low‐energy charge‐carrier (bipolaron) formation significantly. Kinetic studies based on chronoamperometry show that the polymer P5 (EDOT‐capped benzo[1,2,5]oxadiazole system) possess better electrochromic property with high transmittance (66%) in visible region than the other copolymers. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and electrochemical investigation of <Emphasis Type="Italic">beta</Emphasis>-substituted thiophene-based donor–acceptor copolymers with 3,4-ethylenedioxythiophene (EDOT)

The present work reports the synthesis of four electron-acceptor beta-substituted thiophenes that were studied as monomers for electrochemical polymerization with 3,4-ethylenedioxythiophene (EDOT), an electron-donating monomer, aiming the combination of electron-acceptor and donor monomer thiophene to a simpler and convenient build up of novel donor–acceptor copolymeric materials via electrochemical polymerization. Four novel copolymers poly(EDOT-co-3-thiophene phenylacetate), (PEDOT-co-PPhTAc-2a), poly(EDOT-co-3-thiophene(4-nitrophenyl)acetate) (PEDOT-co-PPhTAc-2b), poly(EDOT-co-3-thiophenephenylcarboxylate) (PEDOT-co-PPhTCb), and poly(EDOT-co-3-(phenoxymethyl)thiophene) (PEDOT-co-PPhOMT) were electrochemically polymerized. The monomers were characterized by spectrometric techniques (FTIR, ¹H NMR, and ¹³C NMR), and the copolymers were identified by electrochemical analyses and FT-IR. Although the corresponding homopolymers could not be obtained, in the presence of EDOT, the copolymers were formed in a quasi-reversible electrochemical kinetics. The infrared spectra of the copolymers as well the electrochemical profile corroborates their obtaining. The mass variation during the electrosynthesis was analyzed using a quartz crystal microbalance. The film’s morphologies were investigated by SEM. Interestingly, the combination of electron-rich monomer thiophene (EDOT) and these electron-deficient carboxy-substituted thiophenes might be a convenient building block couple to increase the performance control of physic-chemical properties of mixed polythiophenes with innovative applications and they also showed a possible applicability as charge storage device.     

Synthesis,characterizations, and electrochromic properties of donor–acceptor type polymers containing 2, 1, 3‐benzothiadiazole and different thiophene donors

Three donor–acceptor type π‐conjugated monomers containing 2, 1, 3‐benzothiadiazole (Tz) as the acceptor unit and different thiophene derivatives (thiophene, 3,4‐ethylenedioxythiophene, and thieno[3,2‐b]thiophene) as the donor units have been synthesized via Stille coupling reaction. The corresponding polymers are electrochemically deposited onto FTO glass by cyclic voltammetry (CV). The maximum absorption wavelength of the neutral polymers varies with the electron‐rich character of incorporated thiophene moieties, giving rise to tunable colors. In addition, the prepared polymer films demonstrate reasonable transmittance modulation, fast switching rate, high color efficiency and good stability, which meet the requirements of smart windows and electrochromic display applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2239–2246     

[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     

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.     

All-polymer solar cells with perylenediimide polymer acceptors

Four polymers based on perylenediimide co-polymerized with thiophene, bithiophene, selenophone and thieno[3,2-b]thiophene were investigated as the acceptor materials in all-polymer solar cells. Two different donor polymers, poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b′]dithiophene-2,6-diyl-alt-(4-(2-ethylhexyl)-3-fluorothieno[3,4-b]thiophene)-2-carboxylate-2,6-diyl](PTB7-Th) and poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3′′′-di(2-dodecyltetradecyl)-2,2′;5′,2″;5″,2′′′-quaterthiophen-5,5′′′-diyl)](Pff BT4T-2DT), with suitably complementary absorption spectra and energy levels were applied and examined. Among all different donor-acceptor pairs studied here, the combination of PTB7-Th:poly[N,N′-bis(1-hexylheptyl)-3,4,9,10-perylenediimide-1,6/1,7-diyl-alt-2,5-thiophene](PDI-Th) exhibited the best power conversion efficiency(PCE) of 5.13%, with open-circuit voltage(V_(oc)) = 0.79 V, short-circuit current density(J_(sc)) = 12.35 mA·cm~(-2) and fill-factor(FF) = 0.52. The polymer of PDI-Th acceptor used here had a regio-irregular backbone, conveniently prepared from a mixture of 1,6- and 1,7-dibromo-PDI. It is also noteworthy that neither additive nor posttreatment is required for obtaining such a cell performance.     

Electrochemical and optical studies of furan and thieno[3,2‐b]thiophene end capped benzotriazole derivatives

Two new 2‐dodecyl benzotriazole (BTz) based donor‐acceptor‐donor (DAD) type polymers were synthesized and characterized in terms of their electrochemical and spectral properties. These DAD type polymers were synthesized electrochemically from furan or thieno[3,2‐b]thiophene (TT) end‐capped BTz monomers. Furan based and thieno[3,2‐b]thiophene based monomers showed monomer oxidations at 1.15 and 1.25 V, respectively, which eased the formation of conducting polymer films without overoxidation. Cyclic voltammetry and spectroelectrochemistry studies showed that both materials are multicolored electrochromic polymers. Results and comparison with properties of other BTz based DAD type polymers are highlighted in detail. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Halocyclization of 2-(2-{4-[allylamino(thioxo)methyl]piperazin-1-yl}ethyl)-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">de</Emphasis>]isoquinoline-1,3(2<Emphasis Type="Italic">H</Emphasis>)-dione

Cyclization of 2-(2-{4-[allylamino(thioxo)methyl]piperazin-1-yl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione by the action of iodine, bromine, or sulfuryl chloride gave 2-(2-{4-[4,5-dihydro-5-(halomethyl)-thiazol-2-yl]piperazin-1-yl}ethyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione hydrohalides which were converted into 2-{2-[4-(5-methylthiazol-2-yl)piperazin-1-yl]ethyl}-1H-benzo[de]isoquinoline-1,3(2H)-dione.     

Photocyclization of 2-[1]benzothien-3-yl)-3-phenylpropenoic acids

Photocyclization of the substituted 2-([1]benzothien-3-yl)-3-phenylpropenoic acids 3a-c in the presence of iodine and air in a benzene-cyclohexane mixture afforded a separable mixture of three compounds, benzo[b]naphtho[2,1-d]thiophene-6-carboxylic acids 4a-c , 6H-benzo[b]naphtho[2,3-d]thiopyran-6-ones 5a-c , and 10-methoxy-2-methyl-6H-benzo[b]naphtho[2,3-d]pyran-6-one ( 6 ).     

Derivatives of benzo[4,5]cyclohepta[1,2-b]thiophene. 4. Synthesis of 1-(9,10-dihydro-4H-benzo[4,5]cyclohepta[1,2-b]thiophen-4-yl)-3-alkylaminoazetidines

Thirteen 1-(9,10-dihydro-4H-benzo[4,5]cyclohepta[1,2-b]thiophen-4-yl)-3-alkylaminoazetidines 11 have been synthesized in three steps from 4-amino-9,10-dihydro-4H-benzo[4,5]cyclohepta[1,2-b]thiophene ( 6 ), which was obtained from the reduction of either 4-azido 4 or 4-hydroxyimino 5 derivatives. All the compounds have been evaluated as potential antidepressive agents.     

4-Aminofurazan-3-carboxylic Acid Iminoester in Reactions with N,O-Nucleophiles

Reactions of 4-aminofurazan-3-carboxylic acid iminoester with o-aminophenol and ethylenediamine give rise respectively to 4-(1,3-benzoxazol-2-yl)- and 1-(4,5-dihydro-1H-imidazol-2-yl)-1,2,5-oxadiazol-3-amines, with aminoethanol arises 2-[(Z)-1-amino-1-(4-amino-1,2,5-oxadiazol-3-yl)methylideneamino]-1-ethanol. Treating of 3-amino-4-(1H-benzo[d]imidazol-2-yl)-1,2,5-oxadiazole with triethyl orthoformate in acetic anhydride yielded benzo[4,5]imidazo[1,2-c][1,2,5]oxadiazolo[3,4-e]pyrimidine, and alkylation with haloalkanes furnished 3-amino-4-(1-R-benzo[d]imidazol-2-yl)-1,2,5-oxadiazoles.     

Incorporation of a 2,3-dihydro-1H-pyrrolo[3,4-d]pyridazine-1,4(6H)-dione unit into a donor–acceptor triad: synthesis and ion recognition features

A novel directly-linked donor–acceptor–donor (D–A–D) type system, which is based on 2,3-dihydro-1H-pyrrolo[3,4-d]pyridazine-1,4(6H)-dione as the A unit and thiophene as the D units, respectively, is designed, synthesized, and characterized by spectroscopic methods. This novel D–A–D system can be used for the fluorogenic detection of Cu²⁺ among other ions.     

Synthesis of new 1,2,3-triazole linked benzimidazole molecules as anti-proliferative agents

One pot click chemistry is used to link triazole and benzimidazole pharmacophore to get N-((1-((1H-benzo[d]imidazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)aniline and its derivatives. Flexible linkages in the form of –CH₂–R or –O–R/–N–R were designed during synthesis. All the newly synthesized compounds were characterized by FT-IR and NMR spectroscopy as well as high-resolution mass spectrometry. Selected compounds were screened for in vitro anti-proliferative activity using National Cancer Institute (NCI)-60 human tumor cell line screening program. The most potent structure N-((1-((1H-benzo[d]imidazol-2-yl)methyl)-1H-1,2,3-triazol-4-yl)methyl)-4-chloroaniline 7e showed 40% growth inhibition in renal cancer cell line (UO-31) at 10?µM concentration.     

Synthesis and structure of potassium 2-(pyridin-2-yl)-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">d</Emphasis>]imidazolate and preparation of related bis(diimine) ligands

A potassium derivative of 2-(pyridin-2-yl)-1H-benzo[d]imidazole (BenzimidK) is synthesized and structurally characterized (СIF file CCDC no. 1478559). The complex is used for the preparation of new bis(diimine) ligands containing different diimine fragments linked by the bridging (CH₂)₄ group.     

Transition-metal-free insertion of benzyl bromides into 2-(1H-benzo[d]imidazol-1-yl)benzaldehyde: One-pot switchable syntheses of benzo[4,5]imidazo[1,2-a]quinolin-5(7H)-ones and 3-arylquinolin-4-ones mediated by base

A transition-metal-free insertion of benzyl group between aldehyde and imidazole of 2-(1H-benzo[d]imidazol-1-yl)benzaldehyde was achieved for the first time. Two diverse sets of quinolin-4-one derivatives: benzo[4,5]imidazo[1,2-a]quinolin-5(7H)-ones (2) and 3-arylquinolin-4-ones (3) were synthesized based on identical starting materials 2-(1H-benzo[d]imidazol-1-yl)benzaldehydes (1) and benzyl bromides. In the preparations, two key intermediates I and II were involved and might be synthesized in situ through the reaction of an intra-Breslow intermediate with benzyl bromide via an enol attack in the presence of base or a NHC-based enamine attack in the absence of base, respectively, in which the intra-Breslow intermediate might function as a nucleophilic reagent by following two novel different pathways.     

Synthesis of two new heterocyclic ring systems: Benzo[3,4] cyclohepta[1,2-d]-pyrimidines and benzo[3,4]cyclohepta[2,1-d] pyrimidines

Three 2,4-diamino-l(), 11-dihydro-9H-benzo[3,4]cyclohepta[ 1,2-d]pyrimidines (6a-6c) representing the first examples of a new ring system were synthesized from 2-benzosuberones and cyanoguanidine. Similarly, 2,4-diamino-6,7-dihydro-5H-benzo[3,4]cyelohepta[2,1-d]pyrimidine ( 24 ) was prepared from 1-benzosuberone. The ultraviolet spectral properties of these compounds were examined with reference to those of the analogs in which the central ring is five- and six-mernbered.     

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.     

Modulating the Electron-Donating Ability of Acridine Donor Units for Orange–Red Thermally Activated Delayed Fluorescence Emitters

The development of thermally activated delayed fluorescence (TADF) emitters with orange–red emission still lags behind that of their blue, green, and yellow counterparts. Recent research to address this problem mainly focused on developing new acceptor units. There were few donor units designed especially for orange–red emitters. Herein, with benzothiophene fused to a diphenylacridine donor unit, a new donor moiety, namely, 5,5-diphenyl-5,13-dihydrobenzo[4,5]thieno[3,2-c]acridine (BTDPAc), was designed and synthesized. Benefiting from the strong electron-donating ability of the new donor moiety, a new TADF emitter, 2-[4′-(tert-butyl)(1,1′-biphenyl)-4-yl]-6-[5,5-diphenylbenzo[4,5]thieno[3,2-c]acridin-13(5H)-yl]-1H-benzo[de]isoquinoline-1,3(2H)-dione (BTDPAc-PhNAI), shows an orange–red emission with a maximum at 610 nm in dilute toluene solution. Also, with the help of the diphenyl rings of the donor unit, high photoluminescence quantum yields were achieved for BTDPAc-PhNAI over a wide concentration range. Consequently, an orange–red organic light-emitting diode based on BTDPAc-PhNAI achieved a high external quantum efficiency of nearly 20 %, which was comparable to state-of-the-art device performances with similar emission spectra.     

Tetrahydropyran-2,4-diones in the Synthesis of Fused N,O-Heterocycles

Condensation of 6-methyl(or phenyl)-tetrahydropyran-2,4-diones with 2-aminonaphthalene or 6-aminoquinoline and aromatic aldehydes in an aliphatic alcohol gave 5-aryl-2,2-dimethyl(or 2-phenyl)-1,2,5,6-tetrahydro-4H-benzo[f]pyrano[3,4-c]quinolin-4-ones and 5-aryl-2-methyl-1,2,5,6-tetrahydro-4H-pyrano[4,3-a][4,7]phenanthrolin-4-ones which are new N,O-heterocyclic systems containing fused aza- and diazaphenanthrene moieties and a 2-pyranone ring.