Synthesis of oligophenylenes containing hydroxyl group and their solvatochromic behavior

Oligo(p-phenylene)s containing hydroxyl group(s), namely, OPP(n)-OH (n=3, 4, and 5; n denotes the number of benzene rings), HO-OPP(3)-OH, and 1,3,5-tri(4-biphenyl)phenol TBP-OH were synthesized in high yields by the Suzuki coupling reaction. Absorption maxima (λmaxs) of OPP(n)-OHs shifted progressively toward long wavelengths due to the expansion of the π-conjugation system with an increase in the number of benzene rings. Deprotonation of the OH group of OPP(n)-OHs by treatment with NaH caused a bathochromic shift of λmax. The bathochromic shift of the deprotonated species increased with the donor numbers (DNs) of the solvents. The emission peak positions of OPP(n)-OH and OPP(n)-ONa depended on the DN of the solvents; that is, the emission color could be tuned by changing the solvent.