梅山 有和

Without any added catalyst or radical initiator at 25 °C, cyclo-(MeAs)5 caused cleavage of the arsenic-arsenic bond spontaneously and copolymerized with phenylacetylene (PA) in chloroform to give a novel organoarsenic polymer having a methylarsine (MeAs) unit and a vinylbenzene unit alternating in the main chain, -[AsMe-CH=CPh]n-. The rate of monomer consumption during the copolymerization was followed by a gas chromatography (GC) analysis, and the increase of the molecular weight of the resulting copolymer was monitored by GPC measurement. These analyses revealed that this system was step-reaction polymerization, The consumption of PA during the copolymerization with cyclo-(MeAs)5 using AIBN was much faster as compared to the case without AIBN.

Poly(vinylene arsine)s with no aromatic substituent ([-CH = CR - AsMe - ]n) were prepared through a radical alternating copolymerization of acetylenic compounds having an alkyl substituent with an organoarsenic homocycle as an arsenic-atomic biradical equivalent. The radical reaction between 1-octyne and pentamethylcyclopentaarsine, with a catalytic amount of 2,2′-azobisisobutyronitrile without a solvent (60°C, 10 h), produced the corresponding poly(vinylene arsine)s (45% yield). The copolymers obtained were soluble in tetrahydrofuran, chloroform, hexane, and so on. The copolymers were characterized with 1H and 13C NME spectra. The number-average molecular weights of the copolymers were estimated with gel permeation chromatography (chloroform and polystyrene standards) to be 6500. The copolymers showed an emission property attributable to the n-π* transition in the main chain. Irradiation by an incandescent lamp of a mixture of 1-octyne and 1 also produced poly(vinylene arsine)s. The conversion rate of 1-octyne during the copolymerization with 2,2′-azobisisobutyronitrile was measured with gas chromatography analysis and was found to be much slower than that of phenylacetylene. A radical terpolymerization of cyclo-(AsMe)5 with 1-octyne and styrene was carried out to yield the terpolymer. © 2004 Wiley Periodicals, Inc.

1,2,4,5-Tetramethyltetrahydrodiarsenine (1), a cyclic diarsine compound, was stirred with styrene and a catalytic amount of 2,2′- azobisisobutyronitrile (AIBN) as a radical initiator at 80°C for 8 h in toluene to give a copolymer containing arsenic atoms in the backbone. The gel permeation chromatography (GPC) chromatogram of the copolymer showed a single peak. The number-average molecular weight of the copolymer was estimated to be more than 10,000 by GPC analysis (CHC13, polystyrene standards). The structure of the copolymer was confirmed by the 1H NMR and 13C NMR spectra. According to the integral ratio of peaks in the 1H-NMR spectrum, the content of 1 in the copolymer was smaller compared to the monomer feed ratio of 1. Radical copolymerization of 1 with methyl methacrylate also provided the corresponding copolymer in the presence of AIBN, whereas copolymerization with vinyl acetate yielded no polymeric material. © 2004 Wiley Periodicals, Inc.

The free radical terpolymerization of pentamethylcyclopentaarsine (cyclo-(MA)5), phenylacetylene (PA), and various vinyl monomers in toluene is described. The terpolymerization of cyclo-(MA)5, PA, and styrene (St) in the molar ratio 1:5:5 with a catalytic amount of AIBN at 60°C for 8 h provided a polymer in 38% yield after reprecipitation. The terpolymer was soluble in common organic solvents such as tetrahydrofuran, chloroform, benzene, and toluene. In the GPC analysis (chloroform, PSt standards), the terpolymer showed a single peak, and the number-average molecular weight was estimated to be 10 200. The structure of the terpolymer obtained was compared with those of poly(vinylene-arsine) and polystyrene by use of 1H NMR and 13C NMR and found to have two block units, [poly(MA-alt-PA)-poly(St)]. The integral ratio of the peak area in the 1H NMR spectrum revealed the terpolymer composition, MA:PA:St = 1:0.99:0.56. The terpolymer showed fluorescence properties attributable to the n-π* transition in the poly(MA-alt-PA) block. The terpolymerization of cyclo-(MA)5, PA, and St in various feed ratios was carried out in the presence of AIBN to yield the terpolymers which possessed poly(MA-alt-PA) and poly-(St) blocks with various compositions. The terpolymer with the higher content of St unit exhibited a more blue-shifted emission peak. The radical terpolymerization of methyl methacrylate (MMA) with cyclo-(MA)5 and PA also yielded the corresponding terpolymer with a poly(MA-alt-PA) unit and a poly(MMA) unit, while the terpolymerization employing vinyl acetate (VA) as a vinyl monomer produced poly-(vinylene-arsine) with no VA segment. The radical reaction of 2,3-dimethyl-1,3-butadiene (DB) with cyclo-(AsMe)5 and PA formed a different type of terpolymer which had alternating sequences of AsMe and PA or DB, e.g., [(MA-PA)-(MA-DB)]n.

The radical reaction between hexaphenylcyclohexaarsine (1) and acetylenic compounds with various substituents (2a-d) using a catalytic amount of AIBN provided the corresponding alternating copolymer, poly(vinylene-arsine). The copolymers obtained were soluble in common organic solvents such as THF, chloroform, benzene, and toluene. From gel permeation Chromatographic analysis (chloroform, PSt standards), the number-average molecular weights of the copolymers were found to be several thousands. Structural characterization of the copolymers was provided by 1H and 13C NMR spectroscopies. The measurement of the conversion rate of 2a-d during the copolymerization by using gas chromatography gave an evidence to support the assumption that the formation of vinyl radicals by addition of arsenic radicals to acetylenic compounds was the rate-determining step in this copolymerization system. The copolymer obtained showed fluorescence properties which were influenced by the substituents of the acetylenic compounds.

Novel organoarsenic polymers, poly(vinylene-arsine)s, were synthesized by a free-radical alternating copolymerization of phenylacetylene with cyclooligoarsines as an atomic biradical equivalent. The polymerization between pentamethylpentacycloarsine (1a) or hexaphenylhexacycloarsine (1b) with phenylacetylene (2) in the presence of a catalytic amount of AIBN (in benzene refluxing for 12 h) gave the corresponding poly(vinylene-arsine)s. The obtained polymers were soluble in common organic solvents such as THF, chloroform, and benzene. From gel permeation chromatographic analysis (chloroform, PSt standards), the number-average molecular weights of the polymers from 1a and 1b were found to be 11500 and 3900, respectively. The structures of the polymers were supported by 1H and 13C NMR spectroscopies. The corresponding polymer was also obtained by irradiation of a benzene solution of 1a and 2 with xenon lamp at room temperature. After the polymer from 1a was stirred vigorously with 30% H2O2, the 1H NMR spectrum of the polymer showed the methyl proton that was assigned to As(III)-Me, suggesting the insensitivity of the trivalent state arsenic in the main chain to the oxidation. The structures and the molecular weights of the polymers were insensitive to the feed ratio of the monomers. This result indicates that the addition of the arsenic radical to phenylacetylene was a rate-determining step in the copolymerization.

Alternating acceptor-donor π-conjugated copolymers of cyclodiborazane with dithiafulvene were prepared by hydroboration polymerization of 2,6-bis(p-cyanophenyl)-1,4-dithiafulvene (1) with tripylborane (2a) or mesitylborane (2b). The structures of the polymers 3 were supported by 1H NMR, 11B NMR, and IR spectra. The obtained polymers were soluble in common organic solvents such as tetrahydrofuran, chloroform, and benzene. The peak due to the π-π* transition of 3a was observed at 415 nm, which was bathochromic shifted in comparison with that of the monomer 1 and the corresponding homopolymers. The emission peaks of 3a was observed at 531 nm (excitation wavelength at 415 nm). The cyclic voltammogram showed that 3a was electroactive either in the cathodic or in the anodic region. A soluble charge-transfer (CT) complex of 3a with 7,7,8,8-tetracyanoquinodimethane (TCNQ) was formed when TCNQ was added to a DMSO solution of 3a. Before doping, 3a exhibited an electrical conductivity of 2×10-5 S cm-1 as measured on a cast film from DMSO. The cast film of the CT complex of 3a with TCNQ had a conductivity of 1×10-4 S cm-1.

Hydroboration polymerization of dicyano compounds with intramolecular charge transferred (ICT) structure was made. Extended π-conjugation through the cyclodiborazane unit was observed having intramolecular charge transferred (ICT) structure. The fairly bathochromic shifted absorption edges of the obtained polymers relative to those for model compounds indicate that intra-unit π-conjugation in addition to charge transferred structure should be concerned with the specific electronic state of the present system.

Novel poly(ethynylene-phenylene-ethynylene-borane)s were prepared by polycondensation between bifunctional lithium acetylide and aryldimethoxyborane. The polymers obtained are expected as a novel type of organoboron π-conjugated polymers via vacant p-orbital of boron atom. The polymerization between dilithium 2,5-didodecyloxybenzene-1,4-diethynilide and tripyldimethoxyborane [tripyl=2,4,6-triisopropylphenyl] gave the corresponding polymer in 67% yield. From gel permeation chromatographic analysis (THF, PSt standards), the number-average molecular weight of the polymer was found to be 2700. In the UV-vis spectrum of the polymer (in chloroform at room temperature), an absorption maximum was observed at 397 nm. The fluorescence emission spectrum (in chloroform, room temperature, excitation wavelength at 400 nm) showed its λ(max) at 456 nm in the visible blue region. The polymers obtained were very soluble in common organic solvents such as THF, chloroform and benzene.