Synthesis of a novel macroinimer based on thiophene and poly(ε‐caprolactone) and its use in electrochromic device application

Synthesis of a novel macroinimer comprising poly(ε‐caprolactone) (PCL) and thiophene (Th) and its use in electrochromic device (ECD) application have been reported. First, a novel Th monomer ( 5 ) with miktofuntional initiator groups (primary hydroxyl and tertiary bromide at the third position of the thiophene ring) was synthesized in a four‐step reaction sequence. Density functional theory‐predicted bond lengths, angles, and vibrations of 5 were in good agreement with available experimental vibrational spectra. Subsequently, ring‐opening polymerization of ε‐caprolactone (ε‐CL) was carried out in bulk using 5 as the initiator and tin(II) 2‐ethylhexanoate (Sn(Oct)₂) as the catalyst at 115 °C, which led to α‐thiophene end‐capped PCL macroinimer (PCL‐Th). Furthermore, PCL‐Th macroinimer was used in electrochemical copolymerization with pyrrole (Py) and Th. PCL‐Th/PTh copolymer film synthesized on indium tin oxide‐coated glass slide showed electrochromic behavior. Optical analyses of the PCL‐Th/PTh copolymer film indicated that the copolymer film was suitable to be used as an anodically coloring material for ECD applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Polythiophene formation within hyperbranched grafts on polyethylene films

Interphase oligomerization of thiophene within a supported thin film is described. Polyethylene (PE) surfaces containing an irregularly hyperbranched poly(acrylic acid) (PAA) graft were first prepared by multistep grafting of poly(tert‐butylacrylate) onto oxidized PE. The product ultrathin PAA grafts were then further modified by amidation or esterification with thiophenes containing amino or hydroxyl groups to form new interfaces containing thiophene monomers. These thiophene‐modified grafts were characterized by attenuated total reflectance infrared spectroscopy and were shown to be suitable as substrates in an oxidative polymerization method with FeCl₃ as an oxidant. The product 2,5‐coupled thiophene oligomers (3‐PAA/PE–oligomerized thiophene ester, OTE) emitted a yellow‐green light under UV irradiation, indicating that a conjugated fluorescence oligothiophene had been prepared within these hyperbranched films. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4119–4128, 2001     

Regioselective grignard metathesis reaction of 2,5‐dibromo‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene and kumada coupling polymerization

2,5‐Dibromo‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene ( DBPyTh ) was synthesized by the Suzuki coupling reaction between two aromatic compounds followed by the bromination. The Grignard metathesis reaction of DBPyTh with isopropylmagnesium chloride proceeded in 85% conversion and the regioselective halogen–metal exchange at the 2‐position was confirmed. Namely, 5‐bromo‐2‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene and 2‐bromo‐5‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene were generated in 90:10 molar ratio. Subsequently, the Kumada coupling polymerization was carried out using 1,3‐bis(diphenylphosphinopropane)nickel(II) dichloride to obtain poly(3‐(6′‐hexylpyridine‐2′‐yl)thiophene) ( PolyPyTh ). The polymer molecular weight could be roughly controlled by the catalyst concentration and the molecular weight distribution ranged from 1.25 to 1.80. The gas chromatograph analysis indicated that 5‐bromo‐2‐chloromagnesio‐3‐(6′‐hexylpyridine‐2′‐yl)thiophene was preferentially polymerized in 90% conversion and the percentage of the head‐to‐tail content (regioregularity) was calculated to be 96%. The matrix‐assisted laser desorption/ionization time‐of‐fright mass spectrum indicated that both polymer chain ends were substituted with the hydrogen atom. The absorption maxima of polymer in CHCl₃ and thin film were observed at 447 and 457 nm, respectively, which were blue‐shifted compared with poly(3‐(4′‐octylphenyl)thiophene). From the CV measurement of the polymer thin film, highest occupied molecular orbital (HOMO) (?5.31 eV) and lowest unoccupied molecular orbital (LUMO) (?3.76 eV) energy levels were calculated from the oxidation and reduction onset potentials, respectively, and the electrochemical band gap energy was determined to be 1.62 eV. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

New conducting pyrrole–thiophene co-polymer from an oligomer precursor: electrochemical characterisation

A new oligomer of N,N′-bis(2-pyrrolyl methylene)-3,4-dicyano-2,5-diaminothiophene possessing cyano-substituted thiophene and pyrrole residues linked together by azomethine groups was used for the electrochemical polymerisation of conducting films. The approach used for the oligomer design favours inter-chain interactions through hydrogen bonding and negative charge stability through the cyano substitute thiophene. The oligomer was successfully electropolymerised at 0.67 V vs Ag⁺/Ag from 0.1M tetrabutylammonium tetrafluoroborate (TBABF₄)/acetonitrile as a dark blue film on the surface of platinum electrodes. Cyclic voltammetry has been used to investigate the redox behaviour of the films. The electrically conducting polymer showed p-doping/neutralisation behaviour. The effect of different electrolytes such as TBABF₄, tetrabutylammonium perchlorate (TBAClO₄), lithium perchlorate (LiClO₄) and sodium perchlorate (NaClO₄) on the redox switching and the stability of the polymer films was investigated. Infrared and UV-vis spectra of oligomer and polymers are presented. The evolution of the film growing process is shown by UV-vis spectroscopy.     

High-Performance All-Polymer Solar Cells: Synthesis of Polymer Acceptor by a Random Ternary Copolymerization Strategy

Demonstrated in this work is a simple random ternary copolymerization strategy to synthesize a series of polymer acceptors, PTPBT-ET_x, by polymerizing a small-molecule acceptor unit modified from Y6 with a thiophene connecting unit and a controlled amount of an 3-ethylesterthiophene (ET) unit. Compared to PTPBT of only Y6-like units and thiophene units, PTPBT-ET_x (where x represents the molar ratio of the ET unit) with an incorporated ET unit in the ternary copolymers show up-shifted LUMO energy levels, increased electron mobilities, and improved blend morphologies in the blend film with the polymer donor PBDB-T. And the all-polymer solar cell (all-PSC) based on PBDB-T:PTPBT-ET_0.3 achieved a high power conversion efficiency over 12.5 %. In addition, the PTPBT-ET_0.3-based all-PSC also exhibits long-term photostability over 300 hours.     

噻吩在γ-Mo2N(100)表面上加氢脱硫反应的密度泛函理论研究

利用密度泛函理论研究了γ-Mo₂N(100)表面上的噻吩加氢脱硫(HDS)过程. 噻吩在γ-Mo₂N(100)表面上不同作用形式的结构优化结果显示, η5-Mo₂N吸附构型最稳定, 具有最大的吸附能(-0.56 eV), 此时噻吩通过S原子与Mo2原子相连平行表面吸附在四重空位(hcp 位). H原子和噻吩在hcp位发生稳定共吸附, hcp位是噻吩HDS的活性位点. 噻吩在γ-Mo₂N(100)表面进行直接脱硫反应, HDS过程分为S原子脱除和C₄产物加氢饱和两部分. 过渡态搜索确定了HDS最可能的反应机理及中间产物, 首个H原子的反应需要最大的活化能(1.69 eV),是噻吩加氢脱硫的控速步骤. 伴随H原子的不断加入, 噻吩在γ-Mo₂N(100)表面上优先生成―SH和丁二烯, 随后―SH加氢生成H₂S, 丁二烯加氢饱和生成2-丁烯和丁烷. 由于较弱的吸附, H₂S、2-丁烯和丁烷很容易在γ-Mo₂N(100)表面脱附成为产物.     

Development of a new conjugated polymer containing dialkoxynaphthalene for efficient polymer solar cells and organic thin film transistors

A new semiconducting polymer, poly((5,5‐E‐α‐((2‐thienyl)methylene)‐2‐thiopheneacetonitrile)‐alt‐2,6‐[(1,5‐didecyloxy)naphthalene])) (PBTADN), an alternating copolymer of 2,3‐bis‐(thiophene‐2‐yl)‐acrylronitrile and didecyloxy naphthalene, is synthesized and used as an active material for organic thin film transistors (OTFTs) and organic solar cells. The incorporation of 2,3‐bis‐(thiophene‐2‐yl)‐acrylronitrile as an electron deficient group and didecyloxy naphthalene as an electron rich group resulted in a relatively low bandgap, high charge carrier mobility, and finally good photovoltaic performances of PBTADN solar cells. Because of the excellent miscibility of PBTADN and PC₇₁BM, as confirmed by Grazing Incident X‐ray Scattering (GIXS) measurements and Transmission Electron Microscopy (TEM), homogeneous film morphology was achieved. The maximum power conversion efficiency of the PBTADN:PC₇₁BM solar cell reached 2.9% with a V_oc of 0.88 V, a short circuit current density (J_sc) of 5.6 mA/cm², and a fill factor of 59.1%. The solution processed thin film transistor with PBTADN revealed a highest saturation mobility of 0.025 cm²/Vs with an on/off ratio of 10⁴. The molecular weight dependence of the morphology, charge carrier mobility, and finally the photovoltaic performances were also studied and it was found that high molecular weight PBTADN has better self assembly characteristics, showing enhanced performance. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Acetylation of 2-(1-naphthyl)thiophene

Acetylation of 2-(1-naphthyl) thiophene with acetyl chloride in the presence of SnCl₄, or with acetic anhydride in the presence of H₃PO₄ gives 5-aceto-2-(1-naphthyl) thiophene. 5-Ethyl-2-[1-(3, 4-dihydronaphthyl)] thiophene, 5-ethyl-2-(1-naphthyl) thiophene and 3, 4-diacetoxymercuri-5-ethyl-2-(1-naphthyl) thiophene are now synthesized and characterized.     

Trifluoroborate-substituted polythiophene as a novel conjugated polymer promising for sensing and solid-state reactions

The anodic oxidation of trifluoroborate-substituted thiophene 1 in CH₃CN without added electrolyte yielded at ca. 1.0 V (vs. Ag⁺|Ag) a conjugated polymer film showing electroactivity both in water and organic media. The electrochemical and UV–visible spectroscopic responses of such a material were found to be dependent on the nature of cation.     

High‐Performance All‐Polymer Solar Cells: Synthesis of Polymer Acceptor by a Random Ternary Copolymerization Strategy

Demonstrated in this work is a simple random ternary copolymerization strategy to synthesize a series of polymer acceptors, PTPBT‐ET_x, by polymerizing a small‐molecule acceptor unit modified from Y6 with a thiophene connecting unit and a controlled amount of an 3‐ethylesterthiophene (ET) unit. Compared to PTPBT of only Y6‐like units and thiophene units, PTPBT‐ET_x (where x represents the molar ratio of the ET unit) with an incorporated ET unit in the ternary copolymers show up‐shifted LUMO energy levels, increased electron mobilities, and improved blend morphologies in the blend film with the polymer donor PBDB‐T. And the all‐polymer solar cell (all‐PSC) based on PBDB‐T:PTPBT‐ET_0.3 achieved a high power conversion efficiency over 12.5 %. In addition, the PTPBT‐ET_0.3‐based all‐PSC also exhibits long‐term photostability over 300 hours.     

A theoretical approach to the formation mechanism of diphenyldithieno[3,2-b:2′,3′-d]thiophene from 1,8-diketone, 4,5-bis(benzoylmethylthio)thiophene: a DFT study

The mechanism of formation of dithieno[3,2-b:2′,3′-d]thiophene (DTT) through the reaction of 1,8-diketone, 4,5-bis(benzoylmethylthio)thiophene with P₄S₁₀ was examined in detail by employing DFT method at B3LYP/6-311+G(d,p) level. Two mechanisms were considered. The first one included two parts (i) transformation of the 1,8-diketone, 4,5-bis(benzoylmethylthio)thiophene to the dithione by the reaction of P₄S₁₀ with the carbonyl groups and (ii) cyclization of the dithione to the final product, DTT, through an intramolecular reaction of the thiophene with thiones. The second mechanism consists of an initial attack of the carbonyl oxygen to the phosphorus atom of P₄S₁₀ followed by cyclization via an intramolecular attack from the thiophene ring to the highly electrophilic carbons connected to the oxygens to form DTT. According to the calculated Gibbs free energies of the studied paths, the second mechanism is more favorable than the first one and both pathways proceed in a stepwise manner.     

Preparation and properties of a novel polythiophene,poly[(3‐hexyliminomethyl)thiophene] with a high regioregularity

Poly[(3‐hexyliminomethyl)thiophene]s (P3HITs) were synthesized from the polymerizations of 2,5‐dibromo‐(hexyliminomethyl)thiophene and 5‐bromo‐2‐iodo‐3‐(hexyliminomethyl)thiophene by Grignard metathesis method. The corresponding P3HITs with low regioregularity (70%) and high regioregularity (95%) were obtained, respectively. UV–vis and photoluminescence spectra of P3HIT were dependent on the regioregularity and solvent polarity. By hydrolysis of the imino groups in the side chains under acidic conditions, P3HIT was successfully converted into the polythiophene (P3TCHO) having aldehyde groups. This transformation was also performed facilely by exposing the P3HIT film to HCl gas to give the polythiophene having aldehyde moiety. The reverse way from aldehyde to imine was also successfully demonstrated by treating the film with triethylamine vapor. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Organic sensitizers with different thiophene units as conjugated bridges: molecular engineering and photovoltaics

Three structural modifications with incorporation of alkyl,alkoxy and vinyl bond into the skeleton of thiophene bridge in D-π-A featured organic sensitizers are specifically developed for insight into their influences on photophysical,electrochemical as well as photovoltaic properties in nanocrystalline TiO_2-based dye sensitized solar cells(DSSCs).The insertion of vinyl bond into the conjugation bridge leads to the molecular planar configuration,and the conjugation bridge of 3,4-ethylenedioxythiophene(EDOT)is prone to positively shift its highest occupied molecular orbital(HOMO).The electrochemical impedance spectroscopy(EIS)results indicate that the grafted long alkyl chain onto thiophene is favorable to suppress dye aggregation when adsorbed onto TiO_2film and modification on interface of TiO_2/dye/electrolyte,resulting in a relatively high open-circuit voltage(V_(oc)).Under optimized conditions,dye LS-4 bearing hexylthiophene as the conjugation bridge shows a relatively high overall conversion efficiency of5.45%,with a photocurrent of 11.61 mA cm~(-2),V_(oc)of 744 mV.     

Effect of the Structure of Nonuniform Conducting Polymer Films on Their Electrochemical Impedance Response

Electrochemical impedance spectroscopy is used to characterize thin p-doped polypyrrole (PPy) films in propylene carbonate (PC) solutions and poly(trifluorophenyl)thiophene (PTFPT), in solutions based on sulfolane (SF). It appears that the latter film is much less swelled compared to the former one. One consequence of this difference is that the PTFPT film shows a much higher bulk resistance compared to that for the PPy film. Another important consequence is that the swelling of the PTFPT film is essentially physically non-homogeneous. Two parallel, uncoupled paths, with different chemical diffusion coefficients, model the experimental results adequately. In order to quantify the impedance spectra for both polymer films, we use a model proposed by Rubinstein et al. explaining the difference in the diffusion coefficients of Ru(bpy)^3+/2+ ₃ within a thin Nafion film. The model can also predict the impedance spectra for composite powdery electrodes containing different particle sizes, such as composite cathodes and graphite anodes used in lithium batteries.     

Molecular Assembly by Sequential Ionic Adsorption of Nanocrystalline TiO2 and a Conjugated Polymer

Abstract

Cationic nanocrystalline TiO₂ particles have been synthesized for which the size and composition of the nanoparticles were analyzed by a transmission emission microscopy and energy dispersive x‐ray spectrometer (EDXS). Multilayered films have been fabricated by sequential adsorption of TiO₂ nanoparticles and poly(3‐thiophene acetic acid) (PTAA). Each layer of the nanoparticles and PTAA in the thin film has also been characterized by x‐ray photoelectron spectroscopy, atomic force microscopy, and UV‐visible spectroscopy. These types of multilayered nanocomposite films may find applications in the fabrication of efficient light harvesting photovoltaic cells.     

聚噻吩的光电化学研究

导电聚合物是由一些具有共轭π键的聚合物经化学或电化学掺杂后形成的导电率可从绝缘体延伸到导体范围的一类高分子材料。其中噻吩及其衍生物具有导电率高、环境稳定性好、成膜性好、禁带宽度小等特点,是用做光伏电池的理想材料。相继报道的有聚3-甲噻吩[1]、聚3-己基噻吩[2],聚(3-十一烷基-2,2’-并噻吩)[3]等。对于聚噻吩的光电化学性质的研究,在国际上很少见报道,国内尚未见报道,本文对聚噻吩(PTh)的光电化学性质进行了研究。1实验部分1.1仪器与试剂光电化学实验采用带石英窗口的三电极电解池,工作电极为ITO/PTh膜电极,参比电极为饱和…     

Study on the nature of interaction of thiophene with various hydrides

The nature of interactions of thiophene with various hydrides (Y) (Y = HF, HCl, H₂O, H₂S, NH₃, PH₃) is investigated using ab initio calculations. In contrast with the previous results on similar furan complexes, only the π-type is observed for the thiophene complexes. Variations in complexes geometry can be accounted for by the differences in the electrostatic potential on the aromatic ring. To further study the nature of the intermolecular interactions, an SAPT (the symmetry-adapted perturbation theory) energy decomposition analysis was carried out and the results indicate that the dispersion and electrostatic interactions dominate the thiophene complexes.     

Effect of the addition of sulfur compounds on the hydroformylation of 1-hexene catalyzed by rhodium systems

The effect of the addition of triphenylphosphine sulfide, thiophene, benzo[b]thiophene and dibenzo[b,d]thiophene on the hydroformylation of 1-hexene catalyzed by rhodium complexes RhH(CO)₄, RhH(CO)₂(PPh₃)₂ and RhH(CO)₂(diphos) was studied. The addition of these sulfur compounds did not affect the activity of non modified rhodium precatalysts, decreased the activity of the PPh₃-modified one and increased the activity of the diphos-modified ones, which is indicative of the sulfur tolerance of these precatalysts. The linear to branched ratio (l/b) varied from 0.5 to 3.4 for the non-modified precatalyst, and from 1.7 to 3.3 for the phosphine-modified ones.     

Synthesis,Properties, and π‐Dimer Formation of Oligothiophenes Partially Bearing Orthogonally Fused Fluorene Units

A series of oligothiophenes that incorporate cyclopenta[c]thiophene‐based units bearing spiro‐substituted dialkylfluorene was synthesized. Photophysical measurements indicated that there was no interruption in the conjugation along the oligothiophene backbones, irrespective of the number or position of this unit. Electrochemical measurements showed that the thiophene 7‐mers and 11‐mer exhibit reversible multi‐oxidation waves. The formation of cationic species was clearly observed from UV/Vis/NIR measurements. Furthermore, the UV/Vis/NIR spectra at 223 K under one‐electron oxidation conditions revealed that the unsubstituted thiophene or bithiophene units remained in the absence of intermolecular π–π interactions, whereas the formation of π‐dimeric species was observed for the thiophene 7‐mer containing an unsubstituted terthiophene ( U₃ ) unit. Theoretical calculations indicated that the combination of the U₃ unit and the all‐trans conformation decreased the intermolecular steric repulsion between the fused cyclopentene ring and its facing thiophene, which may contribute to the formation of the dimeric structure.