1H NMR study of deprotonation and complexation of 2,2’-dihydroxybiphenyl derivatives

Deprotonation and complexation with gallium ion Ga(III) of 2,2’-dihydroxybiphenyl derivatives were studied by 1H NMR. The pH dependence observed for chemical shifts of aromatic protons allowed us to obtain pKA1 and pKA2 values. Conformational effects for compounds bearing amide groups were described. Coalescence of methyl signals for pH < pKA2 was explained on the basis of intramolecular interactions through hydrogen bond. Spectra of the complexes for ligands containing amide groups with gallium ions showed that the coordination was unsymmetric and of the "salicylate" type.