The Changes in Conformation and Complexability of 6,6′-Diamino-2,2′-bipyridine by Protonation

The reaction of 6,6′-dibromo-2,2′-bipyridine with ammonia in an autoclave gave 6,6′-diamino-2,2′-bipyridine (DABP) in more than 80% yields. DABP behaved as a diacidic base in the pH range of 0 to 10 with the conformational changes. DABP formed complexes with Cu(II), Ni(II), Co(II), and Zn(II). The amino groups at 6 and 6′ positions play a role as strong electron-donationg groups and not as coordination sites. pKa values and complex formation constants were estimated.