Bidentated Hydrogen Bond from [O−H···N−N···H−O] to [O^-···⁺H−N−N−H⁺···^-O] Structures in Solids

Heteronuclear bidentated N−H−O hydrogen bonds in the (4,4‘-bipyridine)(polynitrophenols)2 system were revealed in terms of X-ray structural analyses, ab-initio calculations, and vibrational spectra. 4,4‘-Bipyridine (AA) and polynitrophenols (D) acted as Brønsted base and acid in solids, respectively. The bidentated hydrogen-bonding interaction in solids was modified between [D-···+H−AA−H+···-D] and [D−H···AA···H−D] through regulating Brønsted acid−base conditions.