Zinc(II) Complexes with a Versatile Multitopic Tetrazolate-Based Ligand Showing Various Structures: Impact of Reaction Conditions on the Final Product Structures

Four new zinc(II) complexes based on the same ligand, {Zn(ptp)(H2O)]2 (1), [Zn(ptp)(CH3OH)]n (2), [Zn(ptp)]n (3), and {[Zn3(ptp)3](DMF)2(H2O)}n (4) [H2ptp = 2,3-bis(pyridine-2-yl)-5,6-di-1H-tetrazol-5-ylpyrazine], have been synthesized by solvothermal methods. All of the complexes have been structurally characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. Structural analyses show that complex 1 possesses a centrosymmetrical neutral dinuclear structure and 2 has 1D right-handed helical chains, with the 21 axis expanding along the crystallographic b direction; 3 features a 2D chiral-layered structure with (6,3) net, and complex 4 displays a 3D porous framework with (4,122) topology. The various architectures (0D, 1D, 2D, and 3D) of these four complexes indicated that reaction conditions (temperature and solvent) play an important role in the formation of such coordination structures; namely, various structures can be obtained from the same reactants by controlling and changing the reaction conditions in this system. The luminescent properties of all of the complexes and the corresponding ligand have been investigated in the solid state at room temperature. Moreover, adsorption properties (N2, H2, O2, CO2, and CH4) of the 4a (desolvated 4) have been studied, and the results show that 4a possesses a moderate capability of gas sorption for N2, H2, O2, and CO2 gases, with high selectivity ratios for O2 over H2 at 77 K and CO2 over CH4 at 273 K.