Abstract:

A tetranuclear cluster crystal [Cu4(Pyims)4]·4H2O·4CH3OH was synthesized from the reaction between cupric perchlorate and 4-(3-pyridyl)-2-mercapto imidazole(PyimsH) in methanol medium at room temperature, and characterized by elemental analysis, IR and single-crystal X-ray diffraction. The results reveal that the compound belongs to tetragonal system with space group I41/a. The cell parameters are a=1.44432(12) nm,b=1.44432(12) nm,c=2.2119(3) nm,α=90°,β=90°, γ=90°,V=4.6142(8) nm3, Z=4,Dc=1.669 Mg/m3,Mr=1159.26, R1=0.0761, wR2=0.1839(I＞2σ). In the cluster molecule, the Cu4+4 core takes a distorted tetrahedron configuration. Four Pyims- ligands coordinate with cuprous ions by N atom of imidazole and S atom of sulfhydryl, and two cuprous ions are linked by one S atom t. The cluster molecules are held together via the N(3)--H(7)-C(7) hydrogen-bondings, which result in a three-dimensional network geometry. The electrochemical behavior of the title cluster was studied by cyclic voltammetry. Through simple dropcoating method, the title cluster was used to modify the surface of glassy carbon electrode(GCE) to fabricate an amperometric sensor. It has been found that the peak potential of the oxygen reduction at the modified electrode is positively shifted from -0.55 V to -0.247 V in pH=5.9 phosphate buffer solution. The obvious decrease of the over potential indicates that the sensor has high electrocatalytic activity to oxygen reduction, which suggests that the title cluster complex can be used as the anode material for fuel cells.

Key words: copper cluster, synthesis, crystal structure, electrocatalysis, oxygen.