The Spatial Configurations and the Ultraviolet Absorption Spectra of Biphenyl and Some Related Compounds

The quantitative relations between the degree of deviation from coplanarity of the molecular configuration and the ultraviolet absorption spectrum as well as the extent of conjugation for the biphenyl-type compounds have been determined by calculations based on the molecular orbital method. On the basis of the results, the spatial configurations of biphenyl, o-methylbiphenyl, o,o′-dimethylbiphenyl, fluorene, 9,10-dihydrophenanthrene, 4,5-methylene-9,10-dihydrophenanthrene, 2, 7-dihydro-3,4-5,6-dibenzoxepin, and 2, 7-dihydro-3,4-5,6-dibenzazepinium-1-spiro-1'″piperidinium bromide have been discussed.