Three Complexes of Zn(II) with Nicotinamide. A Mono-, a Di-, and a Polynuclear Compound

Three complexes of Zn(II) with the general formulas {[Zn(H2O)4(4,4′-BiPy)](NO3)2·2NA·H2O}n(1), [Zn(NA)2Br2]·2NA (2), and [Zn2(CH3COO)4(NA)2]·2H2O (3), where 4,4′-BiPy = 4,4′-bipyridine and NA = nicotinamide, have been synthesized and characterized by means of single-crystal X-ray diffraction (complexes 1 and 2), elemental analysis, FT-IR, fluorescence, 1H and 13C NMR spectroscopy (complexes (2) and (3)), and thermogravimetric analysis. A previously reported complex, [Zn(NA)2(H2O)4](NO3)2·2H2O, was used as a precursor for the synthesis of coordination compounds (1) and (2). X-ray data show that (1) is a 1D polynuclear compound, whereas complex (2) is mononuclear. The Zn(II) ions adopt a slightly distorted octahedral geometry in the polymer and a slightly distorted tetrahedral geometry in the monomer. The antimicrobial activity of complexes (2) and (3) was also evaluated, and complex (3) exhibited superior antimicrobial properties, particularly against the C. albicans strain.