Syntheses, supramolecular architectures and photoluminescence properties of Zn(II) complexes based on 3,5-dihydroxybenzoic and pyridine/pyrazole derived ligands

Five new coordination compounds [Zn(mu-3,5-DHB)(2)(H2O)(2)](n) (1a), (Zn(mu-3,5-DHB)(mu-OH2)(H2O)(2)](n)center dot(3,5-DHB)(n)(4H(2)O) n (1b), (Zn(3,5-DHB)(2)(Isna)(2)]center dot 2H(2)O (2), [Zn(3,5-DHB)(2)(4-Acpy)(2)]center dot 3H(2)O (3) and [Zn (3,5-DHB)(2)(3-Mepz)(2)]center dot H2O (4) (3,5-HDHB = 3,5-dihydroxybenzoic, Isna = isonicotinamide, 4-Acpy = 4-acetylpyridine and 3-Mepz = 3-methylpyrazole) were synthesized in water or water-methanol as solvents. All these compounds have been characterized by elemental analysis, FTIR-ATR and (HNMR)-H-1 spectroscopies and Powder X-ray diffraction (PXRD). For compounds 1b-4, X-ray crystal structures have been determined. In these compounds, 3,5-DHB ligand displays different coordination modes. Complex 1b is a coordination polymer, while the addition of the pyridine/pyrazole ligands in the reaction provokes the formation of monomeric compounds (2-4). Moreover, the crystal packing indicates that these complexes expand into 2D/3D network structures mainly by intermolecular hydrogen bond interactions. Finally, the photoluminescent properties of these complexes in solid state have also been investigated. The strong emission observed for lb indicates that it may be a good candidate for photoluminescent devices.