Studies of Polyphenyls and Polyphenylenes. II. The Synthesis and Physical Properties of Polyphenyls Containing Para Linkage

Twelve linear polyphenyls, including quinque- to octiphenyl, were synthesized by the Ullmann cross-coupling reaction of iodobiphenyl with diiodobenzene or iodoterphenyl. Ultraviolet spectral studies of the polyphenyls indicated that the positions of the K-bands above ca. 260 nm, regardless of the presence of o- or m-phenylene unit(s), may be considered to be an indication of the approximate number of consecutive p-phenylene units. Infrared studies also showed that the locations of strong or medium bands in the 815–850 cm−1 region may give the same information. The HMO calculations of the longest wavelength absorption bands of twenty-four polyphenyls were carried out. A comparison between the calculated and observed wavelengths gave rather good agreement, except in the cases of two compounds. The signals of the proton magnetic resonance spectra of eighteen polyphenyls were assigned tentatively. The correlations between the arrangement of the benzene rings and the spectral patterns are discussed.