A STUDY OF SOLVATOCHROMISM AND PROTON-TRANSFER KINETICS OF 2,2'-DIHYDROXYBIPHENYL

Absorption and fluorescence spectra of 2,2'-dihydroxybiphenyl (DHBP) h ave been studied in different solvents and at various acid concentrati on. When compared to 2-hydroxybiphenyl a blue shift in absorption and a red shift in fluorescence are observed in all solvents. This reveals that (i) the presence of two-OH groups at ortho position makes the mo lecule more twisted in the ground state (ii) the molecule attains plan arity on excitation leading to the formation of intramolecular hydroge n bonding. The stretched sigmoid curves obtained in fluorimetric titra tion are analysed and the excited state rate constants for proton tran sfer reaction are determined using lifetime measurements.