Two Zinc Based Coordination Compounds Constructed from Two Azophenyl Ligands: Syntheses, Crystal Structure, and Photocatalytic Performance

Abstract

Two novel coordination compounds based on zinc ions, 1,10-phenanthroline (phen) and two similar azophenyl ligands, 3,4-dicarboxyl-(3 0 ,4 0 -dicarboxylazophenyl) benzene (3,4-H 4 dczpb), as well as 2,3-dicarboxyl-(2 0 ,3 0 -dicarboxylazophenyl)benzene (2,3-H 4 dczpb), namely [Zn(phen) (2,3-H 2 dczpb)(H 2 O)]ÁH 2 O (1), and [Zn 2 (phen) 4 (3,4-H 2 dczpb)](3,4-H 4 dczpb) 2 Á2H 2 O (2), have been synthesized under hydrothermal conditions, and characterized by single crystal X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), CHN elemental analysis, thermogravimetric analysis (TGA) and UV-Visible diffuse reflectance spectra (UV-Vis DRS). Compound 1 was built up of onedimensional [Zn(phen)(2,3-H 2 dczpb)(H 2 O)] chains, while compound 2 was composed of zero-dimensional discrete [Zn 2 (phen) 4 (3,4-H 2 dczpb)] unit and uncoordinated 3,4-H 4 dczpb. The UV-Vis DRS results revealed that the E g values of compounds 1 and 2 are 3.0 and 2.9 eV, respectively, implying that both 1 and 2 illustrate selective absorption in the ultraviolet region. The photocatalytic activities of degradation of methylene blue (MB) in compounds 1 and 2 under UV light irradiation were conducted, and the results revealed that both 1 and 2 can decompose MB efficiently. Finally, the TGA results exhibited 1 and 2 possess good thermal stability.