- Alternating copolymers based on 2,1,3-benzothiadiazole and hexylthiophene: Positioning effect of hexyl chains on the photophysical and electrochemical properties
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A series of donor-acceptor alternating π-conjugated copolymers based on 2,1,3-benzothiadiazole and hexylthiophene units has been synthesized by the palladium-catalyzed Stille cross-coupling method. Various precursory monomers possessing dibromo and bis(tributylstannyl) functionalities were readily prepared in high yields. Microwave-assisted polymerization proved efficient for the production of high-molecular-weight copolymers, ranging from 13550 to 52490 g mol-1. All copolymers exhibited excellent solubilities in most common organic solvents. The thermal properties of these copolymers were investigated by thermogravimetric analysis and differential scanning calorimetry, and the polymers showed high thermal stabilities. Incorporation of the benzothiadiazole unit into polyhexylthiophene chains affected the photophysical and electrochemical properties. The thin-film absorption spectra of all polymers are significantly red-shifted relative to the corresponding absorption bands in solution and exhibit broader absorption bands. The optical band gaps were estimated to be in the range of 2.02-1.74 eV. The highest occupied and lowest unoccupied molecular orbital energy levels are in the ranges of -5.37 to -5.66 eV and -3.33 to -3.44 eV, respectively. In the X-ray diffraction analysis of the deposited film of the copolymer P3, strong diffraction peaks were observed at 2θ = 5.72° (15.43 A) and 23.12° (3.84 A). These values relate to the distances between chains with interdigitated hexyl chains and to π-π stacking between the conjugated chains.
- El-Shehawy, Ashraf A.,Abdo, Nabiha I.,El-Barbary, Ahmed A.,Lee, Jae-Suk
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- Precise control of quantum dot location within the P3HT-b-P2VP/QD nanowires formed by crystallization-driven 1D growth of hybrid dimeric seeds
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Herein, we report a simple fabrication of hybrid nanowires (NWs) composed of a p-type conjugated polymer (CP) and n-type inorganic quantum dots (QDs) by exploiting the crystallization-driven solution assembly of poly(3- hexylthiophene)-b-poly(2-vinylpyridine) (P3HT-b-P2VP) rod-coil amphiphiles. The visualization of the crystallization-driven growth evolution of hybrid NWs through systematic transmission electron microscopy experiments showed that discrete dimeric CdSe QDs bridged by P3HT-b-P2VP polymers were generated during the initial state of crystallization. These, in turn, assemble into elongated fibrils, forming the coaxial P3HT-b-P2VP/QDs hybrid NWs. In particular, the location of the QD arrays within the single strand of P3HT-b-P2VP can be controlled precisely by manipulating the regioregularity (RR) values of P3HT block and the relative lengths of P2VP block. The degree of coaxiality of the QD arrays was shown to depend on the coplanarity of the thiophene rings of P3HT block, which can be controlled by the RR value of P3HT block. In addition, the location of QDs could be regulated at the specific-local site of P3HT-b-P2VP NW according to the surface characteristics of QDs. As an example, the comparison of two different QDs coated with hydrophobic alkyl-terminated and hydroxyl-terminated molecules, respectively, is used to elucidate the effect of the surface properties of QDs on their nanolocation in the NW.
- Kim, Yong-Jae,Cho, Chul-Hee,Paek, Kwanyeol,Jo, Mijung,Park, Mi-Kyoung,Lee, Na-Eun,Kim, Youn-Joong,Kim, Bumjoon J.,Lee, Eunji
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- Simple non-fullerene electron acceptors with unfused core for organic solar cells
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Two simple electron acceptors based on unfused bithiophene core and 1,1-dicyanomethylene-3-indanone end group were easily prepared via three synthetic steps. These acceptors exhibited broad absorption in the range of 300 nm to 800 nm, aligned energy levels and high crystallinity. When combined with a wide band gap donor polymer in non-fullerene solar cells, an initial power conversion efficiency of 2.4% was achieved. The relatively low efficiencies were due to the large phase separation in blended thin films, which is originated from their high aggregation tendency in thin films. Our results suggest that these electron acceptors with unfused core are promising candidates for commercial application of solar cells due to the low cost starting materials and facile synthesis.
- Li, Yao,Xu, Yunhua,Yang, Fan,Jiang, Xudong,Li, Cheng,You, Shengyong,Li, Weiwei
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- Efficient deep-red electroluminescent donor-acceptor copolymers based on 6,7-dichloroquinoxaline
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Since the large steric hindrance caused by chlorine atoms not only suppresses the aggregation but also results in large stokes shift and low self-absorption, a series of donor-acceptor alternating copolymers based on 6,7-dichloroquinoxaline have been synthesized by modifying the structures of oligothiophenes. All the polymers have been well characterized to study the effects of the length of oligothiophenes and the steric hindrance on the optical, electronic and electroluminescent properties. It was observed that the intramolecular charge transfer absorption was weakened by steric hindrance. Unlike non-chloride analogues, prolonged conjugated length resulted in smaller bandgap, given similar steric hindrance. Deep-red emission centered at 678?nm with brightness about 1800?cd?m?2 was achieved with external quantum efficiency 1.34% using dopant/host technic.
- Gao, Xiang,Zhang, Yubao,Fang, Cheng,Cai, Xiang,Hu, Bin,Tu, Guoli
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- The synthesis of head-to-tail (H-T) dimers of 3-substituted thiophenes by the hypervalent iodine(III)-induced oxidative biaryl coupling reaction
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The head-to-tail (H-T) dimers could be obtained selectively by the oxidative coupling reaction of 3-substituted thiophenes using a combination of hypervalent iodine(III) reagents and trimethylsilyl trifluoromethanesulfonate. The Roval Society of Chemistry 2005.
- Dohi, Toshifumi,Morimoto, Koji,Kiyono, Yorito,Maruyama, Akinobu,Tohma, Hirofumi,Kita, Yasuyuki
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- Simple Separation of an Isomeric Mixture of Dihexylbithiophenes with Head-to-head and Head-to-tail Orientations
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The isomeric mixture of 3,3'-dialkylbithiophenes with head-to-head (H-H) and head-to-tail (H-T) orientations was separated into each isomer by using preferential bromination of the H-T isomer.This separation method proved to be useful for simultaneous preparation of the pure H-H and H-T bithiophenes which are inaccessable by other methods.
- Higuchi, Hiroyuki,Hayashi, Noriyuki,Koyama, Haruki,Ojima, Juro
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- Intramolecular Noncovalent Interaction-Enabled Dopant-Free Hole-Transporting Materials for High-Performance Inverted Perovskite Solar Cells
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Intramolecular noncovalent interactions (INIs) have served as a powerful strategy for accessing organic semiconductors with enhanced charge transport properties. Herein, we apply the INI strategy for developing dopant-free hole-transporting materials (HTMs) by constructing two small-molecular HTMs featuring an INI-integrated backbone for high-performance perovskite solar cells (PVSCs). Upon incorporating noncovalent S???O interaction into their simple-structured backbones, the resulting HTMs, BTORA and BTORCNA, showed self-planarized backbones, tuned energy levels, enhanced thermal properties, appropriate film morphology, and effective defect passivation. More importantly, the high film crystallinity enables the materials with substantial hole mobilities, thus rendering them as promising dopant-free HTMs. Consequently, the BTORCNA-based inverted PVSCs delivered a power conversion efficiency of 21.10 % with encouraging long-term device stability, outperforming the devices based on BTRA without S???O interaction (18.40 %). This work offers a practical approach to designing charge transporting layers with high intrinsic mobilities for high-performance PVSCs.
- Cao, Yan,Chen, Zhicai,Gao, Peng,Guo, Xugang,Huang, Jun,Lai, Ziwei,Liao, Qiaogan,Su, Mengyao,Wang, Dong,Woo, Han Young,Wu, Ziang,Yang, Kun,Zhang, Zilong
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- Synthesis and Characterization of Diferrocenyl Conjugates: Varying π-Conjugated Bridging Ligands and its Consequence on Electrochemical Communication
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Organometallic wire-like complexes with ferrocenyl termini, conjugated with one and two units of thienylethynyl (M1 and M2) and thienyl (M3 and M4) groups, have been synthesized with a general formula of [Fc-C≡C-(Th-C≡C)1-2-Fc] and [Fc-(Th)1-2-Fc] (Fc = ferrocenyl, Th = thienyl) respectively. The diferrocenyl organometallic complexes have been characterized by various spectroscopic tools such as multinuclear NMR, FTIR, elemental analysis, and mass spectrometry. The electrochemical properties of these compounds have been investigated by cyclic (CV) and differential pulse voltammetry (DPV). The single reversible oxidation wave in diferrocenyl complexes with thienylethynyl spacers (M1 and M2) indicates the absence of intramolecular electrochemical communication between the two ferrocenyl termini. Interestingly, the diferrocenyl complexes with one and two thienyl spacers (M3 and M4) show two successive reversible one-electron oxidation waves, indicating electronic coupling between the two ferrocenyl (Fc) termini. The potential difference (ΔE1/2) between the two redox centers is 160 mV and 130 mV, respectively, with the corresponding comproportionation constants (Kc) of 6.2 × 102 and 1.5 × 102. Upon mono-oxidation of M3 by [Cp2Fe][BF4], a broad and weak intervalence charge-transfer (IVCT) transition is observed in the NIR region of 1200–2200 nm.
- Roy, Sourav Saha,Patra, Sanjib K.
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p. 2193 - 2201
(2019/04/17)
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- Convenient synthesis of organic-electronics-oriented building blocks via on-water and under-air homocoupling of (hetero)aryl iodides
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We report herein an operationally simple homocoupling reaction that targets the convenient synthesis of organic-electronically important building blocks. A variety of synthetically useful bithiophene derivatives and functionalized biphenyls are efficiently prepared by an on-water and under-air protocol using Pd/C as catalyst. We find that Pd/C gives generally higher and cleaner homocoupling conversions than using Pd(OAc)2 in the cases of (hetero)aryl iodides since Pd(OAc)2 triggers more side reactions including dehalogenations and oligomerizations. Under the optimum conditions, a broad range of functional groups such as ester, ketone, aldehyde, nitrile, nitro, chloride, and bromide are well tolerated. We expect the present methodology would make a valuable synthetic contribution towards bridging green chemistry with thiophene-based organic materials.
- Chen, Yi-An,Liu, Ching-Yuan
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p. 74180 - 74188
(2015/09/21)
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- Topological considerations for the design of molecular donors with multiple absorbing units
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The molecule AT1, with two weakly conjugated chromophores, was designed, synthesized, and examined within the context of its film forming tendencies. While the addition of the second chromophore to the central core enables broadening of the absorption spectrum, this change is mostly apparent in films that are grown slowly. Grazing incidence X-ray scattering (GIWAXS) analysis indicates that these spectral characteristics correspond to an increase in solid state ordering. This information, in combination with differential scanning calorimetry, suggests that the overall molecular shape provides a kinetic barrier to crystallization. As a result, one finds the absence of molecular order when AT1 is combined with PC71BM in solution-cast blends. These findings highlight the importance of molecular topology when designing molecular components for solar cell devices.
- Lai, Lai Fan,Love, John A.,Sharenko, Alexander,Coughlin, Jessica E.,Gupta, Vinay,Tretiak, Sergei,Nguyen, Thuc-Quyen,Wong, Wai-Yeung,Bazan, Guillermo C.
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supporting information
p. 5591 - 5594
(2014/05/06)
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- Impact of molecular symmetry on single-molecule conductance
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We have measured the single-molecule conductance of a family of bithiophene derivatives terminated with methyl sulfide gold-binding linkers using a scanning tunneling microscope based break-junction technique. We find a broad distribution in the single-molecule conductance of bithiophene compared with that of a methyl sulfide terminated biphenyl. Using a combination of experiments and calculations, we show that this increased breadth in the conductance distribution is explained by the difference in 5-fold symmetry of thiophene rings as compared to the 6-fold symmetry of benzene rings. The reduced symmetry of thiophene rings results in a restriction on the torsion angle space available to these molecules when bound between two metal electrodes in a junction, causing each molecular junction to sample a different set of conformers in the conductance measurements. In contrast, the rotations of biphenyl are essentially unimpeded by junction binding, allowing each molecular junction to sample similar conformers. This work demonstrates that the conductance of bithiophene displays a strong dependence on the conformational fluctuations accessible within a given junction configuration, and that the symmetry of such small molecules can significantly influence their conductance behaviors.
- Dell, Emma J.,Capozzi, Brian,Dubay, Kateri H.,Berkelbach, Timothy C.,Moreno, Jose Ricardo,Reichman, David R.,Venkataraman, Latha,Campos, Luis M.
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supporting information
p. 11724 - 11727
(2013/09/02)
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- Donor-acceptor semiconducting polymers containing benzodithiophene with bithienyl substituents
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Synthesis and photovoltaic properties of two donor-acceptor polymers containing benzodithiophene with 3,3,5-trihexylbithienyl substituents are reported. Benzo[c][1,2,5]thiadiazole and 5-hexylthieno[3,4-c]pyrrole-4,6-dione were used as acceptor building bl
- Kularatne, Ruvini S.,Sista, Prakash,Nguyen, Hien Q.,Bhatt, Mahesh P.,Biewer, Michael C.,Stefan, Mihaela C.
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p. 7855 - 7862,8
(2020/09/15)
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- Band structure engineering for low band gap polymers containing thienopyrazine
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In this research, we demonstrated that the energy levels, including highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), and the optical absorptions of low band gap conjugated copolymers, consisting of 3-hexylthiophene (3HT) as electron-donating units and 2,3-diethylthieno[3,4-b]pyrazine (ETP) as electron-accepting units, could be systematically tuned by adjusting the composition and the geometric structure of the copolymers. Four new copolymers comprising of 3HT and ETP in different molar ratios (from 1:1 to 4:1), named P1-P4, were designed and synthesized via Suzuki coupling. The positions of the hexyl side chains on 3HT were varied to adjust the co-planarity of the copolymers. The LUMO, ranging from -2.94 eV to -3.11 eV, was lowered monotonically with increasing ETP content, and the break of co-planarity along the main chain showed a trivial effect on the LUMO. By contrast, the HOMO (-4.74 eV to -4.88 eV) was controlled by both the composition and the geometric structure of the copolymer. P2, having a twisted geometric structure, possessed a lower HOMO and a larger band gap compared to the planar P3. Bimodal optical absorptions with a relatively stronger absorption at long wavelengths were observed for all polymers which are due to intramolecular charge transfer. Optical band gaps in solution, ranging from 1.27 eV to 1.76 eV, decreased with increasing ETP content in the copolymer except P2 and the trend was consistent with the HOMO-LUMO gaps. The optical absorptions and the energy levels are further confirmed by theoretical calculations. Good co-planarity was also found to benefit the electrical conductivity of p-doped thin films. Our results suggested that tuning the composition and the geometric structure would be an effective molecular design strategy toward desired band structure for low band gap conjugated polymers based on thiophene and thienopyrazine derivatives.
- Chao, Chi-Yang,Chao, Chung-Hsiang,Chen, Lung-Pin,Hung, Ying-Chieh,Lin, Shiang-Tai,Su, Wei-Fang,Lin, Ching-Fuh
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experimental part
p. 7331 - 7341
(2012/06/01)
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- LiCl-promoted chain growth kumada catalyst-transfer polycondensation of the "reversed" thiophene monomer
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The effect of LiCl on the chain growth Kumada catalyst-transfer polycondensation (KCTP) of the "reversed" thiophene monomer, 5-bromo-2-chloromagnesio-3-hexylthiophene (3a) (that has bulky substituent adjacent to the chloromagnesium group), was investigate
- Wu, Shupeng,Huang, Li,Tian, Hongkun,Geng, Yanhou,Wang, Fosong
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scheme or table
p. 7558 - 7567
(2012/07/30)
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- Synthesis of a new conjugated polymer composed of pyrene and bithiophene units for organic solar cells
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An alternating conjugated copolymer composed of pyrene and bithiophene units, poly(DHBT-alt-PYR) has been synthesized. The synthesized polymer was found to exhibit good solution processibility and thermal stability, losing less than 5% of their weight on heating to approximately 370 °C. The synthesized polymer showed its maximum absorption and peak PL emission at 401 and 548 nm, respectively. The optical band gap energy of the polymer was determined by absorption onset to be 2.64 eV. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of the polymer was determined to be-5.48 and-2.84 eV by cyclic voltametry (CV) and the optical band gap. The polymer photovoltaic devices were fabricated with a typical sandwich structure of ITO/PEDOT:PSS/active layer/LiF/Al using poly(DHBT-alt-PYR) as an electron donor and C60-PCBM or C70-PCBM as electron acceptors. The open circuit voltage, short circuit current and fill factor of the device using C70-PCBM as an acceptor were 0.75 V, 3.80 mA/cm 2 and 0.28, respectively, and the maximum power conversion efficiency of the device was 0.80%. Copyright
- Lee, Sun-Young,Jung, Choong-Hwa,Kang, Jun,Kim, Hee-Joon,Shin, Won Suk,Yoon, Sung Cheol,Moon, Sang-Jin,Lee, Changjin,Hwang, Do-Hoon
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p. 4367 - 4372
(2012/06/16)
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- A successful chemical strategy to induce oligothiophene self-assembly into fibers with tunable shape and function
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Functional supramolecular architectures for bottom-up organic nano- and microtechnology are a high priority research topic. We discovered a new recognition algorithm, resulting from the combination of thioalkyl substituents and head-to-head regiochemistry of substitution, to induce the spontaneous self-assembly of sulfur overrich octathiophenes into supramolecular crystalline fibers combining high charge mobility and intense fluorescence. The fibers were grown on various types of surfaces either as superhelices or straight rods depending on molecular structure. Helical fibers directly grown on a field effect transistor displayed efficient charge mobility and intrinsic 'memory effect'. Despite the fact that the oligomers did not have chirality centers, one type of hand-helicity was always predominant in helical fibers, due to the interplay of molecular atropisomerism and supramolecular helicity induced by terminal substituents. Finally, we found that the new sulfur overrich oligothiophenes can easily be prepared in high yields through ultrasound and microwave assistance in green conditions.
- Di Maria, Francesca,Olivelli, Pasquale,Gazzano, Massimo,Zanelli, Alberto,Biasiucci, Mariano,Gigli, Giuseppe,Gentili, Denis,D'Angelo, Pasquale,Cavallini, Massimiliano,Barbarella, Giovanna
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p. 8654 - 8661
(2011/07/29)
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- ELECTRON DONATING ORGANIC MATERIAL, MATERIAL FOR PHOTOVOLTAIC ELEMENT, AND PHOTOVOLTAIC ELEMENT
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The invention aims at providing a photovoltaic device with high photoelectric conversion efficiency. The aim is attained by an electron donating organic material containing a benzothiadiazole compound in which (a) a benzothiadiazole skeleton and an oligothiophene skeleton are contained, (b) a band gap (Eg) is 1.8 eV or less, and (c) the level of the highest occupied molecular orbital (HOMO) is -4.8 eV or less, wherein said benzothiadiazole compound is formed by covalently combining the benzothiadiazole skeleton and the oligothiophene skeleton alternately, the proportion between the benzothiadiazole skeleton and the oligothiophene skeleton is within a range of 1:1 to 1:2 (however, excluding 1:1), and the number of thiophene rings contained in an oligothiophene skeleton is 3 or more and 12 or less.
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Page/Page column 37-38
(2011/01/12)
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- Hypervalent iodine(III): selective and efficient single-electron-transfer (SET) oxidizing agent
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In 1994, we first determined the single-electron-transfer (SET) oxidation ability of phenyliodine(III) bis(trifluoroacetate) (PIFA) toward phenyl ethers, affording the corresponding aromatic cation radicals. Since then, hypervalent iodine(III) has been utilized as a selective and efficient SET oxidizing agent that enables a variety of direct C-H functionalizations of aromatic rings in electron-rich arenes under mild conditions. We have now extended the original method to work in a series of heteroaromatic compounds such as thiophenes, pyrroles, and indoles. The investigations and results obtained since the start of this century are summarized in this article.
- Dohi, Toshifumi,Ito, Motoki,Yamaoka, Nobutaka,Morimoto, Koji,Fujioka, Hiromichi,Kita, Yasuyuki
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experimental part
p. 10797 - 10815
(2010/03/01)
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- The influence of poly(3-hexylthiophene) regioregularity on fullerene-composite solar cell performance
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A comparison of three samples of poly(3-hexylthiophene) having regioregularities of 86, 90, and 96% is used to elucidate the effect of regioregularity on polymer-fullerene-composite solar cell performance. It is observed that polymer samples with lower regioregularity are capable of generating fullerene composites that exhibit superior thermal stability. The enhanced thermal stability of the composites is attributed to a lower driving force for polymer crystallization in the less regioregular polymer samples, which is supported with two-dimensional grazing incidence X-ray scattering and differential scanning calorimetry measurements. Furthermore, it is demonstrated that all three polymer samples are capable of generating solar cells with equivalent peak efficiencies of ~4% in blends with [6,6]-phenyl-C 61 -butyric acid methyl ester. While it may be non-intuitive that polymers with lower regioregularity can exhibit higher efficiencies, it is observed that the charge-carrier mobility of the three polymers is on the same order of magnitude (10-4 cm-2 V-1 s -1) when measured from the space-charge-limited current, suggesting that highly regioregular and crystalline polythiophenes are not required in order to effectively transport charges in polymer solar cells. Overall, these results suggest a design principle for semicrystalline conjugated polymers in fullerene-composite solar cells in which crystallization-driven phase separation can be dramatically suppressed via the introduction of a controlled amount of disorder into the polymer backbone.
- Woo, Claire H.,Thompson, Barry C.,Kim, Bumjoon J.,Toney, Michael F.,Frechet, Jean M. J.
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supporting information; experimental part
p. 16324 - 16329
(2009/05/09)
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- Palladium-catalyzed C-H homocoupling of bromothiophene derivatives and synthetic application to well-defined oligothiophenes
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Synthesis of oligothiophenes of well-defined structures that possess 2-8 thiophene units is performed with a new synthetic strategy involving C-H homocoupling of bromothiophenes and cross-coupling with organostannanes. Tolerance of the carbon-bromine bond to the palladium-catalyzed C-H homocoupling results in oligothiophenes bearing C-Br bonds at the terminal thiophene rings, which allow further transformation by the catalysis of a transition-metal complex.
- Takahashi, Masabumi,Masui, Kentaro,Sekiguchi, Hiroki,Kobayashi, Nobuhiko,Mori, Atsunori,Funahashi, Masahiro,Tamaoki, Nobuyuki
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p. 10930 - 10933
(2007/10/03)
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- Electropolymerization of bithienyl-appended cerium(III) triple decker porphyrin complex
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A cerium(III) triple decker porphyrin complex bearing bithienyl substituents (1) at the peripheral meso-positions was synthesized. Electrochemical polymerization of the triple decker porphyrin gave a unique polymer film on the ITO electrode surface without decomposition.
- Yamashita, Kousei,Ikeda, Masato,Takeuchi, Masayuki,Shinkai, Seiji
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p. 264 - 265
(2007/10/03)
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- A novel and direct synthesis of alkylated 2,2′-bithiophene derivatives using a combination of hypervalent iodine(III) reagent and BF3·Et2O
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A novel nonmetallic oxidative coupling of alkylthiophene derivatives leading to the corresponding 2,2′-bithiophene derivatives using a combination of a hypervalent iodine(III) reagent, phenyliodine bis(trifluoroacetate) (PIFA), and BF3·Et2O was developed.
- Tohma, Hirofumi,Iwata, Minako,Maegawa, Tomohiro,Kiyono, Yorito,Maruyama, Akinobu,Kita, Yasuyuki
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p. 1647 - 1649
(2007/10/03)
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- Synthesis and Properties of Dihexylbithienoquinonoid Derivatives with Head-to-head, Head-to-tail, and Tail-to-tail Orientations
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2,2′-(Dihexyl-2,2′-bithienylidene-5,5′-diylidene) bis(propanedinitrile)s (dihexylbithienoquinonoid derivatives), in which two 3-hexylthiophene moieties are connected with head-to-tail (HT) and tail-to-tail (TT) orientations, were synthesized. HT bithienoquinonoid was isolated in a single form together with a small amount of its bromo derivative, similarly to the case for the head-to-head (HH) orientational isomer. On the other hand, TT isomer exhibited a peculiar feature in solution, affording an equilibrium mixture of two geometrical isomers. Electronic and electrochemical properties of these bithienoquinonoids were studied and compared with those of HH isomer. The results proved that all these bithienoquinonoid compounds possess highly polarizable and electron-acceptable properties. HH bithienoquinonoid was reduced through one two-electron transfer process, while HT and TT isomers were reduced through two one-electron transfer processes via stable radical anions to the corresponding dianions.
- Higuchi, Hiroyuki,Yoshida, Shima,Uraki, Yoshiyuki,Ojima, Juro
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p. 2229 - 2237
(2007/10/03)
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- Syntheses and Properties of Unsymmetrically Substituted Bi- and Ouaterthiophenes
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The unsymmetrically substituted bi- and quaterthiophene derivatives were synthesized. The unsymmetrically substituted bithiophenes carrying the electron-withdrawing substituent X on one of the outer thiophene rings exhibited the maxima of absorption bands at the longer wavelengths than the symmetrically disubstituted bithiophene derivatives, while the unsymmetrical quaterthiophenes had such maxima at the shorter wavelengths than the corresponding symmetrical ones. The trend of bathochromic shift of the longest wavelength absorption bands due to the electron-withdrawing substituent X was more pronounced in case of bi- or quaterthiophenes bearing push-pull substituents. The unsymmetrical quaterthiophenes exhibited the greater third-order nonlinear optical (TNLO) properties than the corresponding bithiophenes, similarly to the case between the symmetrical bi- and quaterthiophenes. However, the TNLO properties of the unsymmetrical biand quaterthiophenes showed no dependence on the electron-withdrawing strength of the substituent X, unlike those of the symmetrical ones.
- Higuchi, Hiroyuki,Uraki, Yoshiyuki,Yokota, Hiroki,Koyama, Haruki,Ojima, Juro,Wada, Tatsuo,Sasabe, Hiroyuki
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p. 483 - 495
(2007/10/03)
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- Synthesis and Properties of α,ω-Disubstituted Oligo(3-hexylthiophene)s and Oligothienoquinonoids in Head-to-head Orientation
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The two types of Highly-ordered oligo(3-hexylthiophene)s in head-to-head orientation, a series od α,ω-disubstituted oligothiophenes and a series of bis(dicyanomethylene)oligothienoquinonoids, were synthesized.The properties of these compounds are discussed on the basis of the electronic spectra and cyclic voltammetry.
- Higuchi, Hiroyuki,Nakayama, Taketoshi,Koyama, Haruki,Ojima, Juro,Wada, Tatsuo,Sasabe, Hiroyuki
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p. 2363 - 2378
(2007/10/03)
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- SELECTIVE FUNCTIONALIZATION OF 2,2'-BITHIOPHENES
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The selective functionalization of the 2,2'-bithiophene molecule is described.Selective alkyl substitution at the 3,3'-positions was achieved by sequential bromination of the 3,3' and 5,5' positions followed by debromination at the 5,5'-positions.The resultant 3,3'-dibromo-2,2'-bithiophene was transformed via a Grignard reaction to give a series of 3,3'-dialkyl-2,2'-bithiophenes.Finally, nitration of the active 5,5'positions gave the corresponding 3,3'-dialkyl-5,5'-dinitro-2,2'-bithiophenes.
- Khor, Eugene,Ng, Siu Choon,Li, Hwee, Chze,Chai, Selenium
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p. 1805 - 1812
(2007/10/02)
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