Poly(phenylacetylene) with bulky chiral germyl groups: synthesis and effects of measuring solvents and temperature on chiroptical properties

(+)-p-[{Methyl(1-naphthyl)phenyl}germyl]phenylacetylene, an acetylene with a bulky chiral germyl group, was polymerized with [(nbd)RhCl](2)-Et3N to gi ve a high-molecular-weight polymer in good yield. The CD spectrum of the po lymer exhibited very large molar ellipticities [0] in the UV region in non- aromatic solvents (e.g. THF and CHCl3). In contrast, the CD signals of the polymer in aromatic solvents (e.g. toluene, tetralin, and benzene) became a ppreciably smaller: [0](max) = 6.4 x 10(4) (330 nm) and -4.7 X 10(4o), cm(2 ) dmol(-1) (370 nm) in CHCl3; [0](max) = 1.1 x 10(4) (330 nm) and - 0.7 x 1 0(4o) cm(2) dmol(-1) (370 nm) in toluene. The [0](max) values of the polyme r in aromatic solvents increased when the solutions were heated, which is a ttributed to decreased pi-pi interaction between the solvents and side grou ps. (C) 2001 Elsevier Science Ltd. All rights reserved.