Synthesis, crystal structures and fluorescence properties of two 1D Zn(II) homologous coordination polymers

A pair of zinc(II)-based one-dimensional (1D) homologous coordination polymers, [Zn(Hdba)2(bib)]n (1) and [Zn(Hdba)(2)(bmib)](n) (2), where H(2)dba = 3-hydroxybenzoic acid, bib = 1,4-bis(1-imidazolyl)benzene, and bmib = 1,4-bis(2-methyl-1H-imidazol-1-yl)benzene were hydrothermally synthesized and characterized through infrared spectroscopy (IR), elemental and thermal analysis (EA), powder X-ray diffraction (PXRD), and single-crystal X-ray diffraction (SCXRD) analyses. The results revealed that 1 and 2 have the same zigzag infnite chain framework through the partially deprotonated Hdba- monodentate linkage and with mu(2)-bib bridging the Zn(II) atoms in 1, and with mu 2-bmib bridges for the Zn(II) atoms in 2. For both 1 and 2, each zinc atom has a slightly twisted tetrahedral confguration with a N2O2 donor set. These chains of 1 and 2 are further connected into three-dimensional (3D) supramolecular structures through O-HmiddotmiddotmiddotO, C-HmiddotmiddotmiddotO hydrogen bonds and nmiddotmiddotmiddotn, C-Hmiddotmiddotmiddotn stacking interactions for 1, and O-HmiddotmiddotmiddotO, C-HmiddotmiddotmiddotO hydrogen bonds for 2. Topologically, the 3D hydrogen-bonded organic framework or the 2D n-stacking structure of 1 can be simplifed as a 4-connected dia Diamond type with a Schl & auml;fli symbol {6(6)}, or as a 4-connected sql type with a Schl & auml;fli symbol {4(4)middot6(2)} and a Shubnikov tetragonal plane net. The thermal stability and the solid-state fluorescence properties of 1 and 2 were investigated.