Palladium-catalyzed formation and reactions of iodo- and bromosiloxane intermediates

Polysiloxanes are useful materials because of their functionality, such as high thermal stability, electrical resistance, and hydrophobicity. In this regard, we studied palladium-catalyzed formation of iodo-and bromopolysiloxanes from two types of hydrosiloxanes, alpha,omega-dihydropoly(dimethylsiloxane) (1) and cyclotetra(hydromethylsiloxane) (2), and their reactions. Treatment of 1 with mixtures of cyclic ethers or lactones and MeI or allylBr in the presence of a catalytic amount of PdCl2 gave the corresponding alpha,omega-bis(haloalkoxy and haloalkanoyloxy) poly(dimethylsiloxane)s in good yields, via iodo-and bromopoly(dimethylsiloxane) intermediates. Transformation of the iodobutoxy-terminal units in the resulting poly(dimethylsiloxane) into aminoalkoxy groups was examined. The formation of alpha,omega-diiodo- and dibromopoly(dimethylsiloxane)s from 1 was confirmed by spectrometric analysis as well as by quenching experiments with ethanol. A reaction of alpha,omega-dibromopoly(dimethylsiloxane) with 2,5-dilithiothiophene gave a polydimethylsiloxane-thiophene alternating polymer. Similar palladiumcatalyzed reactions of 2 with THF/MeI, THF/allylBr, and delta-valerolactone/allylBr afforded cyclo(halobutoxy- and bromobutanoyloxymethylsiloxane) s in moderate yields. This would provide a new strategy for the introduction of various substituents to the terminal positions of linear polysiloxane and to the cyclosiloxane core

Synthesis and reactions of poly[(ethoxysilylene)phenylenevinylene]s and chain-to-pendant energy transfer in the resulting polymer

Reactions of (bromophenylethenyl)diethoxysilanes with magnesium in THF gave poly[(ethoxysilylene)phenylenevinylene]s. The ethoxy group of the polymers could be readily replaced with other substituents by treating them with nucleophiles. Optical properties of the resulting poly(silylenephenylenevinylene)s were examined with respect to their UV absorption and emission spectra. Of those, pyrenylethynyl-substituted one exhibited energy transfer from the backbone to the substituent in the photo-excited state

Synthesis of a Novel Family of Polysilsesquioxanes Having Oligothiophenes with Well-Defined Structures

Our recent results on the synthesis and properties of a novel family of polysilsesquioxanes having oligothiophenes were reviewed. The polymers anchored on SiO2 or ITO substrates showed excellent mechanical hardness due to the formation of a three-dimensional siloxane network structure and chemical linkage between polymer and the surface of metal-oxide substrates. Optical, electrochemical, and electrical properties of polymers were also investigated

Synthesis and optical properties of spirobi(dithienometallole)s and spirobi(dithienothiametalline)s

Spiro-condensed dithienometalloles (metal - Si, Ge) and dithienothiametallines (metal - Si, Ge, Sn) were prepared by the ring closure reactions of dilithiated bithiophene and dithienyl sulfide with metal tetrachlorides, and their optical properties were studied with respect to the UV absorption and emission spectra. The absorption and emission maxima of them moved to higher energies by increasing the size of the center metal from Si to Ge and Sn, and stepwise oxidation of the ring sulfur atom in the dithienothiasiline system forming sulfoxide and sulfone linkages, making the fine tuning of the electronic states possible

Effects of annealing of poly(3-hexylthiophene) film on the performance of double-layered EL devices of ITO/polymer/Alq3/Mg-Ag

Double layer devices with a structure of ITO/pHT/Alq3/Mg-Ag (ITO = indium tin oxide, pHT = regio-regular or random poly(3-hexylthiophene), Alq3 = tris(8-hydroxyquinoline)aluminium) were fabricated. The device with a random pHT film emitted a green-yellow light in all voltage region, while that having a regio-regular pHT film exhibited a color change from green to red by applying the bias voltage higher than 15 V. Annealing the pHT films prepared on ITO at 200 °C for 1 h in nitrogen, prior to vapor-deposition of the Alq3 layer, improved the device performance with lowering the onset bias voltage by 2-3 V. The EL colors and spectra were also affected by annealing. X-ray reflectivity measurements before and after annealing the pHT film on ITO indicated increased density of the pHT layer and structural changes in the pHT/ITO interface by annealing, which seems to be responsible for the improved EL device performanc

Synthesis, characterization, and photovoltaic applications of dithienogermole-dithienylbenzothiadiazole and -dithienylthiazolothiazole copolymers

New dithienogermole-based conjugated polymers were synthesized by the Stille coupling reactions of distannyldithienogermole and dibromoarene, and their photovoltaic properties were studied. These polymers possess low band gaps with broad absorptions covering the 400-800 nm range, and exhibit good film forming properties. Bulk hetero-junction solar cells prepared from blends of these polymers with PC(70)BM exhibit high power conversion efficiency up to 2.38%

オルガノシラン類の遷移金属触媒反応

Contents General Introduction / p1 Part I Reactions of(Phenylethynyl)polysilanes and Silacyclopropenes with TransitionMetal-Complexes 　Chapter1 Formation and Reactions of a Nickelasilacyclobutene / p6 　Chapter2 Isomerization of 2-Aryl-2-(phenylethynyl)hexamethyltri-silane in the Presence of Tetrakis-(triethylphosphine)nickel(0) / p26 　Chapter3 Platinum-Catalyzed Reaction of(Phenylethynyl)disilanes / p42 　Chapter4 Tungsten-Catalyzed Reactions of Silacyclopropenes / p48 Part II Transition-Metal-Catalyzed C-H Bond Activation of Ethynylsilanes / p61 　Chapter5 Synthesis and Reactions of(E)-1,4-Bis(sily1)-Substituted Enynes / p61 　Chapter6 Nickel-Catalyzed Reactions of Ethynylsilanes for the Formation of Dienyne Systems / p74 　Chapter7 Synthesis and Properties of Poly[(disilanylene)butenyne-1,4-diyls]and Poly[(methyl-phenylsilylene)butenyne-1,4-diyl] / p84 List of Publications / p107広島大学(Hiroshima University)博士(工学)Engineeringdoctora

Group 14 metalloles condensed with heteroaromatic systems

There has been keen interest in group 14 metalloles as building units of conjugated organic functional materials. This short review summarizes our recent work on group 14 metalloles condensed with heteroaromatic systems, including thiophene and pyridine. These condensed metalloles show interesting properties depending on both the group 14 metallole elements and the heteroaromatic systems. High planarity of the condensed systems and interaction between the element σ*-orbital and the heteroaromatic π*-orbital enhance the conjugation in these systems leading to their potential applications as functional materials, such as carrier transporting materials and emissive materials

Synthesis and Heat Resistance of Arylenedioxy-organosilanylene Polymers with Adamantane Units

Arylenedioxy-organosilanylene polymers with adamantane units in the backbone were prepared by Rh-catalyzed dehydrocoupling of bis(4-hydroxyphenyl)adamantanes with organohydrosilanes, and their heat resistance was evaluated by thermogravimetric analysis in nitrogen. Among these polymers, the highest T d 10 (10 % weight loss temperature) of 547 • C was achieved for polymer 2a prepared from 1,3-bis(4-hydroxyphenyl)adamantane and phenylsilane. Polymer 2a exhibited good heat resistance even in air with T d 10 = 387 • C, and standing of the polymer at 150 • C for 8 h resulted in no evident weight loss