- Chalcogen Bridged Thieno- and Selenopheno[2,3- d:5,4- d′]bisthiazole and Their Diketopyrrolopyrrole Based Low-Bandgap Copolymers
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We report the synthesis and characterization of four novel small bandgap copolymers incorporating the electron-deficient thieno[2,3-d:5,4-d′]bisthiazole and selenopheno[2,3-d:5,4-d′]bisthiazole building blocks with a series of electron-deficient diketopyrrolopyrole units. The four resultant copolymers were synthesized via palladium Stille cross-coupling reaction, and their optical, thermal stability, electrochemical, and field-effect charge transport properties were investigated. All copolymers showed low optical bandgaps (1.53-1.56 eV); in addition, X-ray diffraction on solution-cast films revealed that the selenium-containing copolymers exhibit higher crystallinity compared to their thiophene counterparts.
- Patra, Dhananjaya,Lee, Jaehyuk,Dey, Somnath,Lee, Jongbok,Kalin, Alexander J.,Putta, Anjaneyulu,Fei, Zhuping,McCarthy-Ward, Thomas,Bazzi, Hassan S.,Fang, Lei,Heeney, Martin,Yoon, Myung-Han,Al-Hashimi, Mohammed
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- Mixed triorganotin compounds, R3Sn-X-SnR'3: 119Sn NMR evidence for their formation in solution
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119Sn NMR spectroscopy has been used to demonstrate the existence, for hte first time, of mixed triorganotin compounds, R3Sn-X-SnR'3, where R or R' = Bu, Ph or cyclo-C6H11 and X = O or S.These species exist in solution in equilibrium with the correspondin
- Blunden, S. J.,Hill, R.
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p. 317 - 322
(2007/10/02)
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- Organotin-Mediated Selective Desulfurization: Tri-n-butyltin Hydride Reduction of Unsymmetric Sulfides
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Tri-n-butyl hydride (TBTH) has been evaluated as a selective agent for the reductive cleavage of one C-S-bond in unsymmetric sulfides 1.Sulfides 1 (RR1) (where combinations of R and R1 included primary, secondary, tertiary, benzylic, phenyl, allylic, and α-(to carbonyl) carbon bound to sulfur> were each reacted with 1 equiv of TBTH in the presence of AIBN initiator.Reduction by TBTH occurs initially at the R1-S bond (where R1 can form the more stable carbon radical intermediate) in sulfide 1 selectively, if not specifically, to yield hydrocarbon 4 and tributylstannyl alkyl sulfide 3.However, this specifity can be negated by an enhanced reacitivity toward reduction by TBTH which the C-S bond in 3 exhibits, producing hydrocarbon 6 and bis(tributyltin) sulfide.The degree of selectivity in desulfurization is determined by the competition between unsymmetric sulfide 1 and alkyl organotin sulfide 3 for TBTH.The reduction of secondary and primary alkyl C-S bonds in 1 is so slow as to discount the synthetic utility of trialkyltin hydride reduction for such sulfides.
- Gutierrez, Carlos G.,Summerhays, Leo R.
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p. 5206 - 5213
(2007/10/02)
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- Tri-n-butyltin Hydride: A Selective Reducing Agent for 1,3-Dithiolanes
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Tri-n-butyltin hydride has been found to be an effective and selective agent for complete or partial desulfurization of 1,3 dithiolanes 1.The reaction of 1 with 4 equiv of tri-n-butyltin hydride in the presence of 2,2'-azobis(isobutyronitrile) results in complete desulfurization, giving hydrocarbons 2 in good yield, ethane and bis(tri-n-butyltin) sulfide.Two equivalents of hydride specifically cleave the two geminal C-S bonds in 1 to give hydrocarbons 2 and bis(tri-n-butylstannyl) ethanedithiolate.One equivalent of tri-n-butyltin hydride reduces 1 quantitatively to the β-ethyl tri-n-butyltin sulfides 11.
- Gutierrez, Carlos G.,Stringham, Rex A.,Nitasaka, Tadashi,Glasscock, Karl G.
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p. 3393 - 3395
(2007/10/02)
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- Urethane prepolymer
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A polyurethane prepolymer composition comprising (1) not less than 0.65 by weight of the idealized adduct from trimethylolpropane with 3 moles of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate and (2) not more than 0.05 by weight of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate relative to the whole composition is very suitable for an isocyanate component of a two-package urethane coating and gives a coating film having excellent gloss, weathering resistance, adhesivity and impact resistance.
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