A series of new polyoxometalate-based metal-organic complexes with different rigid pyridyl-bis(triazole) ligands: assembly, structures and electrochemical properties

作者：Wang, Xiuli^*; Bai, Xue; Lin, Hongyan; Sun, Junjun; Wang, Xiang; Liu, Guocheng

来源：RSC Advances, 2018, 8(40): 22676-22686.

DOI：10.1039/c8ra03277g

• COMPOSITE ELECTRODE
• HYBRID COMPOUNDS
• CU-II
• FRAMEWORKS
• ARCHITECTURE
• CLUSTERS
• ACID
• ION
• FABRICATION
• OXIDATION

Five new polyoxometalate (POM)-based metal-organic complexes (MOCs) with different rigid pyridyl-bis(triazole) ligands, namely, H{Co-2(Hpyttz-I)(2)(H2O)(6)[CrMo6(OH)(6)O-18]}8H(2)O (1), {Co-2(H(2)pyttz-I)(2)(H2O)(4)[TeMo6O24]}[Co(H2O)(6)]3H(2)O (2), {Co-3(Hpyttz-II)(2)(H2O)(6)[-Mo8O26]}10H(2)O (3), {Ni-3(Hpyttz-II)(2)(H2O)(6)[-Mo8O26]}10H(2)O (4), {Ni-3(Hpyttz-III)(2)(H2O)(8)[-Mo8O26]}10H(2)O (5) (H(2)pyttz-I = 3-(pyrid-2-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl, H(2)pyttz-II = 3-(pyrid-3-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl, H(2)pyttz -III = 3-(pyrid-4-yl)-5-(1H-1,2,4-triazol-3-yl)-1,2,4-triazolyl), were successfully synthesized and structurally characterized by single-crystal X-ray diffraction, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Complex 1 is a two-dimensional (2D) supramolecular network based on the binuclear complex unit: [Co-2(Hpyttz-I)(2)(H2O)(6) [CrMo6(OH)(6)O-18]]. Complex 2 is a 1D supramolecular chain derived from the binuclear cobalt complex: {Co-2(H(2)pyttz-I)(2)(H2O)(4)[TeMo6O24]}(2-), the discrete [Co(H2O)(6)](2+) units act as counter cations. Complexes 3 and 4 are isostructural with different center metals (M = Co or Ni), the adjacent -Mo8O264- anions are linked by the M-II ions to form a 1D M--Mo8O26 inorganic chain. Then 1D M--Mo8O26 inorganic chains are linked together by the 1D metal-organic M-(Hpyttz-II) chains to form a 3D framework. In complex 5, -Mo8O264- anions are bridged by the Ni-II ions to give a 1D Ni--Mo8O26 inorganic chain, the adjacent 1D Ni--Mo8O26 chains are connected through [Ni(Hpyttz-III)(2)] units to form a 2D layer. The effect of POM type and coordination site of the ligands on the structures of the title complexes were discussed. The title complexes 1, 2 and 5 exhibit excellent bifunctional electrocatalytic activities toward the reduction of bromate/hydrogen peroxide and the oxidation of ascorbic acid. In addition, the redox potentials of complexes 1, 2 and 5 are highly sensitive to pH and may be used as a kind of potential pH sensor.

• 出版日期2018
• 单位渤海大学