Synthesis and photovoltaic properties of alternative copolymers of benzo[1,2-b:4,5-b′]dithiophene and thiophene

Two conjugated polymers containing benzodithiophene (BDT) unit and the unit of thiophene or thieno[3,2-b]thiophene, P(BDT-T) and P(BDT-TT), were synthesized by Pd-catalyzed Stille coupling method. The UV–Vis absorption, thermal, and electrochemical properties of the two polymers were characterized. Photovoltaic properties of the polymers were studied by using the polymers as donor and PC₇₀BM as acceptor with a weight ratio of polymer: PC₇₀BM of 1:1.5. The power conversion efficiencies of the PSC devices based on P(BDT-T) reached 2.05% with an open-circuit voltage of 0.75 V, a short-circuit current of 4.5 mA cm⁻², and a fill factor of 0.61, under the illumination of AM1.5, 100 mW cm⁻².     

Synthesis and simultaneously enhanced photovoltaic property of poly[4,4,9,9-tetra(4-octyloxyphenyl)-2,7-indaceno[1,2-b:5,6-b′]dithiophene-alt-2,5-thieno[3,2-b]thiophene]

An alternating conjugated polymer derived from 4,4,9,9-tetra(4-octyloxyphenyl)indaceno[1,2-b:5,6-b′]dithiophene and thieno[3,2-b]thiophene was synthesized by Stille coupling reaction. The copolymer shows extensive absorption from 360 nm to 590 nm with optical band gap of 2.12 eV. The highest occupied molecular orbit (HOMO) and the lowest unoccupied molecular orbit (LUMO) energy levels of the copolymer, determined by cyclic voltammetry (CV), are about ?5.29 eV and ?3.01 eV, respectively. A field-effect hole mobility of 8.1 × 10^?4 cm²/(V s) and an on/off ratio of 2.0 × 10³ are obtained in the field-effect transistors based on the copolymer. The J_sc, V_oc and FF of the polymer photovoltaic cells (PVCs) based on the copolymer were enhanced simultaneously via the inserting of alcohol soluble conjugated polymer interlayer between active layer and metal cathode, and the maximal power conversion efficiency of 4.19% was achieved in the modified devices under an AM 1.5 simulator (100 mWcm^?2).     

Synthesis and properties of novel donor–acceptor copolymers based on thiophene and squaraine moieties

Two novel donor–acceptor copolymers were synthesized by Sonogashira cross-coupling of alkyl/alkoxy thiophene and dibromo-substituted squaraine moieties. The structures and properties of these polymers were characterized using FT–IR, NMR, UV–Vis, gel permeation chromatography, and cyclic voltammetry. Both copolymers are readily soluble in common organic solvents. The polymer films exhibit broad absorption in the wavelength range from 300 to 1000 nm with the maximum peaks over 750 nm. Electrochemical studies reveal that the band gaps of the polymers range from 1.05 to 1.36 eV. Compared to the alkyl thiophene, the alkoxy thiophene units can effectively lower the band gap and result in significant red-shift absorption spectrum of the resulted polymer. The strong overlap of the solar spectrum and the extremely low band gaps of the polymers suggest that they may be promising candidates for solar cells.     

Novel D-π-A system based on zinc porphyrin dyes for dye-sensitized solar cells: Synthesis, electrochemical, and photovoltaic properties

We have designed and synthesized novel zinc porphyrin dyes which have a D-π-A system based on porphyrin derivatives containing a triphenylamine (TPA) electron-donating group and a phenyl carboxyl anchoring group substituted at the meso position of the porphyrin ring, yielding the push-pull porphyrins as the most efficient green dye for dye-sensitized solar cell (DSSC) applications. The synthesis and characterization of a novel D-π-A system based on zinc-porphyrin derivatives have been investigated through their photophysical and photoelectrochemical studies. A large red-shift of the absorption maxima due to introduction of the TPA moiety at the meso position of the porphyrin ring was expected in the D-π-A porphyrins, but the absorption maxima of HKK-Por dyes were a little red-shifted in contrast to Zn[5,-10,15-triphenyl-20-(4-carboxylphenyl)-porphyrin], due to the tilted structure between TPA and the porphyrin unit. Under the photovoltaic performance measurement, the maximum incident photon-to-current conversion efficiency (IPCE) value of the DSSC based on HKK-Por 5 was slightly higher than the efficiencies of the DSSCs based on other HKK-Por dyes due to the introduction of the alkoxy group into the TPA moiety at the meso position of the porphyrin ring. A maximum photon-to-electron conversion efficiency of 3.36% was achieved with the DSSC based on HKK-Por 5 dye (J_SC = 9.04 mA/cm², V_OC = 0.57 V, FF = 0.66) under AM1.5 irradiation (100 m Wcm⁻²).     

Fluorescence and photophysical properties of D-π-A push-pull systems featuring a 4,5-dicyanoimidazole unit

Absorption and fluorescence spectra and fluorescence quantum yields of 18 D-;π-A push-pull compounds were measured. The investigated chromophores consist of 4,5-dicyanoimidazole — bearing donor — substituted and systematically extended π-conjugated spacers. The influence of temperature and solvent polarity on the spectral and photophysical properties was investigated. Employing INDO/S calculations, the structure-property relationships were discussed.     

Fluorescence and photophysical properties of D-π-A push-pull systems featuring a 4,5-dicyanoimidazole unit

Absorption and fluorescence spectra and fluorescence quantum yields of 18 D-;π-A push-pull compounds were measured. The investigated chromophores consist of 4,5-dicyanoimidazole — bearing donor — substituted and systematically extended π-conjugated spacers. The influence of temperature and solvent polarity on the spectral and photophysical properties was investigated. Employing INDO/S calculations, the structure–property relationships were discussed.     

Synthesis,optical and electrochemical properties of novel D-π-A type conjugated polymers based on benzo[c][1,2,5]selenadiazole unit via alkyne module

Three novel donor-π-acceptor (D-π-A) type conjugated polymers P-1, P-2, and P-3 based on benzo[c][1,2,5]selenadiazole moiety and phenyl or naphthyl group via alkyne module were firstly prepared by Sonogashira–Hagihara reaction of various diiodo aryl compounds with the key monomer 4,7-diethynylbenzo[c] [1,2,5]selenadiazole (M-1), which was synthesized by a strategy of firstly introducing the trimethylsilylacetylene flexible group, and then introducing the selenium atom. The polymers displayed obvious absorption peaks at the region from 503 to 510 nm and narrow orange-red or red fluorescence in the range of 576–595 nm because benzo[c][1,2,5]selenadiazole unit can effectively reduce the lowest unoccupied molecular orbital (LUMO) energy levels of these polymers. The band gaps of these polymers can be tuned in the range of 1.37–1.76 eV by using different aryl donor groups. These findings indicate that these benzo[c][1,2,5]selenadiazole-based conjugated polymers can be developed for excellent fluorescent materials.     

Synthesis of D–A low-bandgap polymer-based thieno[3,4-b]pyrazine and benzo[1,2-b:4,5-b′]dithiophene for polymer solar cells

Three D–A low-bandgap polymer-based benzo[1,2-b:4,5-b′]dithiophene (BDT) and thieno[3,4-b]pyrazine (TP) unit with different substituents were synthesized using Stille coupling. The substituent effects were explored. It is found that attaching the phenyl group at the 2,3-positions of thienopyrazine unit is beneficial to good coplanarity and regularity of molecular packing. Meanwhile, attaching the longer alkoxyl side chain at BDT unit or phenyl group at the 2,3-positions of thienopyrazine unit had the relatively deep HOMO (LUMO) energy levels. The three D–A polymers showed good thermal stability and exhibited broad absorption, low bandgap, and order packing structure. As a result, the highest PCE of 1.50 % was achieved for the polymer P2 with the substituents, including hexyldecyloxyl at the BDT unit and phenyl at the TP unit.     

Studies on heterocyclic β-enaminonitriles: Synthesis of new condensed thieno[2,3-b]pyridines containing N-heterocyclic moieties

New versatile enaminonitrile-type building blocks, 3-aminothieno[2,3-b]pyridine-2-carbonitriles 3a,b, were synthesized from 3-cyanopyridine-2-(1H)-thiones 1a,b. Interaction of 3a,b with triethyl orthoformate furnished the corresponding ethoxymethylideneamino derivatives 6a,b. Derivatives of heterocyclic systems having the pyrazole, pyrimidine, and pyridine rings were obtained from the key precursors 3a,b and 6a, respectively.     

Two-photon absorption dyes with thiophene as π electron bridge: Synthesis, photophysical properties and optical data storage

Four novel dyes are prepared by thiophene as π bridge between carbazole central core and other terminal groups by Suzuki and Heck coupling reactions. These dyes are fully characterized by IR, ¹H NMR, ¹³C NMR, MS and elemental analysis. Linear absorption, single- and two-photon excited fluorescence in various solvents are experimentally investigated. The calculated two-photon absorption cross sections of 9-Hexyl-3,6-di((5-phenyl)-2-thienyl)carbazole (1), 9-Hexyl-3,6-di((5-thienyl)-2-thienyl)carbazole (2), 9-Hexyl-3,6-di((5-p-vinylpyridyl)-2-thienyl)-carbazole (3) and 9-Hexyl-3,6-di-((5-o-vinylpyridyl)-2-thienyl)carbazole (4) for the lowest excited state are 537.84, 550.76, 1292.95 and 1340.40 × 10⁻⁵⁰ cm⁴ s photon⁻¹, respectively. Calculated and experimental data have shown that thiophene as π electron bridge improves the two-photon absorption cross sections greatly. Two-photon optical data recording experiments have been carried out at 820 nm laser radiation.     

Synthesis of imidazo[2,1-b]thiazoles through the reaction of thiohydantoins and α-bromoketones

Imidazo-fused heterocycles are used as anticancer agents. In this study, some novel imidazo[2,1-b]thiazoles were synthesized from thiohydantoins and α-bromoketones in good yields. This method has the advantages of simple operation, high yields, and mild reaction conditions and uses less toxic and low-cost chemical reagents.     

Dithieno[3,2-b:2′,3′-d]pyrrole-based materials: Synthesis and application to organic electronics

The application of dithieno[3,2-b:2′,3′-d]pyrroles (DTPs) in conjugated organic polymers has resulted in a variety of materials with reduced and low band gaps that exhibit high carrier mobilities, as well as enhanced solution and solid-state fluorescence. While DTP-based materials date back to the early 1990s, significant advances in the preparation and scope of these materials have been reported over the past decade. In this current report, we provide the first full review of DTP-based materials, highlighting in particular the recent advances made in the synthesis of both monomeric DTPs and their resulting materials, as well as the current progress of their application to various devices, including FETs, OPVs, OLEDs, and electrochromics.     

Synthesis, morphology and mechanical properties of linear triblock copolymers based on poly(α-methylene-γ-butyrolactone)

A series of well-defined triblock copolymers containing middle soft poly(n-butyl acrylate) (PBA) block and outer hard blocks of poly(α-methylene-γ-butyrolactone) homopolymer (PMBL) or random poly (α-methylene-γ-butyrolactone)-r-poly(methyl methacrylate) copolymer (PMBL-r-PMMA) were synthesized by atom transfer radical polymerization (ATRP). Phase separated morphologies of cylindrical or spherical hard block domains arranged in the soft PBA matrix were observed by atomic force microscopy and small-angle X-ray scattering. The mechanical and thermal properties of the copolymers were thoroughly characterized and their thermoplastic elastomer behavior was studied. Dynamic mechanical analysis (DMA) showed for all PMBL-b-PBA-b-PMBL copolymers a very broad rubbery plateau range extending up to temperatures of 300 °C. Replacement of the PMBL hard block with the less brittle PMBL-r-PMMA resulted in an improvement of the tensile properties, without compromising the very good thermal stability of the materials.     

Synthesis and Antimicrobial Evaluation of Some Novel Bis-α,β-Unsaturated Ketones,Nicotinonitrile, 1,2-Dihydropyridine-3-carbonitrile,Fused Thieno[2,3-b]pyridine and Pyrazolo[3,4-b]pyridine Derivatives

The title compounds were prepared by reaction of 1,1′-(5-methyl-1-phenyl-1H-pyrazole-3,4-diyl)diethanone (1) with different aromatic aldehydes 2a–c, namely Furfural (2a), 4-chlorobenzaldehyde (2b) and 4-methoxybenzaldhyde (2c) to yield the corresponding α,β-unsaturated ketones 3a–c. Compound 3 was reacted with malononitrile, 2-cyanoacetamide or 2-cyanothioacetamide yielded the corresponding bis[2-amino-6-(aryl)nicotinonitrile] 4a–c, bis[6-(2-aryl)-2-oxo-1,2-dihydropyridine-3-carbonitrile] 5a–c or bis[6-(2-aryl)-2-thioxo-1,2-dihydropyridine-3-carbonitrile] 6a,b, respectively. The reaction of compound 6a with each of 2-chloro-N-(4-bromophenyl) acetamide (7a), chloroacetamide (7b) in ethanolic sodium ethoxide solution at room temperature to give the corresponding 4,4′-(5-methyl-1-phenyl-1H-pyrazole-3,4-diyl)bis-6-(2-furyl)thieno[2,3-b]pyridine-2-carboxamide] derivatives 9a,b. While compound 6a reacted with hydrazine hydrate yielded the 4,4′-(5-methyl-1-phenyl-1H-pyrazole-3,4-diyl)bis[6-(2-furyl)-1H-pyrazolo[3,4-b]pyridin-3-amine] 11. The structures of the products were elucidated based on their spectral properties, elemental analyses and, wherever possible, by alternate synthesis. Antimicrobial evaluation of the products was carried out.     

Synthesis of poly[2-(α-d-mannopyranosyloxy)ethyl-co-2-dimethylaminoethyl methacrylates] and its lectin-binding and DNA-condensing properties

Radical copolymerizations of 2-(α-d-mannopyranosyloxy)ethyl methacrylate (ManEMA) with 2-dimethylaminoethyl methacrylate (DMAEMA) were carried out in N,N-dimethylformamide (DMF) containing 10 vol% water at 60 °C to yield cationic glycopolymers. The number-average molecular weights (M_ns, standard Pullulan calibration) and polydispersities (M_w/M_ns) of the resulting copolymers were ranged from 17,400 to 41,700 and from 1.7 to 3.2, respectively. The compositions of the resulting copolymers were very close to those in the feed. The monomer reactivity ratios r_ManEMA and r_DMAEMA were 0.98 and 1.22, respectively. The lectin-binding properties of poly(ManEMA-co-DMAEMA) to concanavalin A (ConA) was examined using a turbidimetric assay. The clustering rate increased with increasing mole fractions of the ManEMA units in the copolymer (F_ManEMA), even under a constant concentration of the ManEMA units (50 μM), indicating the typical cluster glycoside effect. The DNA-condensing ability of the resulting copolymers was examined by a gel retardation assay using pEGFP-N1 plasmid (4.7 kbp). Though the ManEMA units interfered with the complexation of the copolymer with the plasmid DNA, complete retardation was observed under the condition of lower contents of ManEMA units (F_ManEMA < 0.2) in pure water. These findings indicate that poly(ManEMA-co-DMAEMA) is a cationic glycopolymer exerting lectin-binding and DNA-condensing abilities.     

A new POMOF consisting of [VW12]4 − clusters and metal-organic nanotubes: Synthesis,structure, electrocatalytic and luminescent properties

A novel compound, [Co₂(bimb)₂VW₁₂O₄₀] [bimb]·6H₂O (1) (bimb = 1.4-bis(1-imidazolyl)benzene), with polyoxometalate-based metal-organic framework (POMOF), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, infrared spectrum, X-ray photoemission spectra, elemental analyses, and powder X-ray diffraction pattern. In the compound, there are metal-organic nanotubes formed by [Co₂(bimb)] ^4 + zig-zag chains and six-connected VW₁₂ guest clusters. Further, the neighboring metal-organic nanotubes are connected together via sharing the [Co₂bimb]^4 + zig-zag chains to achieve a highly opened POMOF with hexagonal apertures, representing the first POMOF constructed by V-centered tungstovanadate. Electrochemical and luminescent properties of the compound were also investigated.     

The effect of changes in π-conjugated terthienyl systems using thienyl and ethylenedioxybenzene functionalized thieno[3,4-b]pyrazine precursors: Multicolored low band gap polymers

New classes of thieno[3,4-b]pyrazines containing thienyl and ethylenedioxy phenyl units on electron-withdrawing moieties of π-conjugated terthienyl were synthesized. The effect of structural differences on electrochemical and optoelectronic properties of the resulting polymers was investigated. Changes in the electronic nature of the functional groups enable to tune the electrochemical properties of the π-conjugated terthienyl monomers by lowering oxidation potential from 0.62 V (DTTP) to 0.56 V (DBTP). Spectroelectrochemical analyses revealed that the neutral polymer (PDBTP) is dark green in its neutral state revealing π-π* transitions in two well-separated bands at 410 and 751 nm. The electronic band gap of polymer, defined as the onset of the π-π* transition, is found to be 1.0 eV. Using the thienyl unit instead of ethylenedioxy phenyl, a red shift in the band gap (0.95 eV) is observed. The polymer, PDTTP, exhibits multicolor electrochromism and can be switched between a dark yellow neutral state, a green intermediate state, and a brown oxidized state. PDBTP also shows a multicolored electrochromic behavior with three distinct states: dark green at the neutral state, a brown intermediate state, and a brown-violet oxidized state.     

Structure-Based Design,Synthesis, and Biological Evaluation of Imidazo[4,5-b]Pyridin-2-one-Based p38 MAP Kinase Inhibitors: Part 2

We identified novel potent inhibitors of p38 mitogen-activated protein (MAP) kinase using a structure-based design strategy, beginning with lead compound, 3-(butan-2-yl)-6-(2,4-difluoroanilino)-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one ( 1 ). To enhance the inhibitory activity of 1 against production of tumor necrosis factor-α (TNF-α) in human whole blood (hWB) cell assays, we designed and synthesized hybrid compounds in which the imidazo[4,5-b]pyridin-2-one core was successfully linked with the p-methylbenzamide fragment. Among the compounds evaluated, 3-(3-tert-butyl-2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-6-yl)-4-methyl-N-(1-methyl-1H-pyrazol-3-yl)benzamide ( 25 ) exhibited potent p38 inhibition, superior suppression of TNF-α production in hWB cells, and also significant in vivo efficacy in a rat model of collagen-induced arthritis (CIA). In this paper, we report the discovery of potent, selective, and orally bioavailable imidazo[4,5-b]pyridin-2-one-based p38 MAP kinase inhibitors.