Syntheses and Spectral Properties of Several Unsymmetrical Sexiphenyls

抄録

Six sexiphenyls, including four new isomers, 2, 3'-di (4-biphenylyl) biphenyl (2), 4-(2-biphenylyl)-o-(4), 4-(2-biphenylyl)-m-quaterphenyl (5), and 2-phenyl-p-quinquephenyl (6), were synthesized by the Ullmann cross-coupling of iodobiphenyl and diiodobiphenyl or of two kinds of iodoterphenyls. The characteristic bands of the infrared spectra (680-920 cm^-1) and signals of the proton magnetic resonance spectra of the sexiphenyls were assigned tentatively and are discussed briefly. The remarkable high field shifts of the p-phenylene proton signals in 4 (1.23 and 0.89 ppm) as compared with that of p-terphenyl (δ 7.68) presumably reflect the ring current effects caused by the presence of adjacent o-phenylene rings. Ultraviolet spectral studies indicated that the absorption curves of the sexiphenyls were related closely to those of the polyphenyls corresponding to their partial structures.