Photoisomerization and emission properties of trans- and cis-poly(dimethylsilylenephenylenevinylene)s

The photoirradiation of trans- and cis-poly(dimethylsilylenephenylenevinyle ne)s gave cis-rich mixtures at equilibrium states. The degree of the photoi somerization could be exactly evaluated by comparing the UV spectra of the photoirradiated solutions with those of the trans and cis polymers. The geo metric configuration of the trans and cis polymers was thermally stable and hardly changed even though they were heated. The trans and cis polymers ex hibited different emission properties; e.g., trans polymer: lambda (max) = 400 nm, quantum yield = 3.4 x 10(-3); cis polymer: lambda (max) = 380 nm, q uantum yield = 1.5 x 10(-3).