Preparation, characterization and crystal structures of copper(II) hexaazamacrotetracyclic complexes with organic ligands

Abstract

The reaction of [Cu(L)](ClO 4 ) 2 AE H 2 O (L ¼ 1, 3,10,12,16,19-hexaazatetracyclo[17,3,1,1 12.16 ,0 4.9 ]tetracosane) with NaN 3 and Na 2 tp yields mononuclear and dinuclear copper(II) complexes, [Cu(L)(N 3 )](ClO 4 ) (1) and [Cu(L)(ltp)](ClO 4 ) AE 2H 2 O (2). These complexes have been characterized by X-ray crystallography, electronic absorption, cyclic voltammetry and magnetic susceptibility. The crystal structure of (1) shows that the copper(II) ion has a distorted square-pyramidal geometry with the two secondary and two tertiary amines of the macrocycle and one nitrogen atom from the azide group coordinating the axial position. The copper(II) ions in (2) are bridged by the terephthalate anion to form a dinuclear complex, in which each copper(II) ion reveals a distorted square-pyramid with four nitrogen atoms of the macrocycle and the oxygen atom of bridging tp ligand. Cyclic voltammetry of the complexes gives two one-electron waves corresponding to Cu II /Cu III and Cu II /Cu I processes. The magnetic susceptibility measurement for (2) exhibits a weak antiferromagnetic interaction between copper(II) centers with a 2J value of )2.21 cm )1 (H ¼ )2JSS 1 AE S 2 ). The electronic spectra and electrochemical behavior of the complexes are significantly affected by the nature of the organic ligands.

Electron Transfer from Graphene Quantum Dots to the Copper Complex Enhances Its Nuclease Activity

“…These observations indicate that the electron-transfer between GQDs and complex 1 did occur. The result is also consistent with the data that the nuclease activity of complex 1 or 2 alone is higher than that of the complex 3 or 4 , because the Cu II in the former two complexes can be reduced more easily than the latter two (Figure ). − It is clear that to have such electron-transfer from GQDs to the complex take place, there must be interactions between the complexes and GQDs. If such interaction between a complex and GQD does not occur, the nuclease activity of the complex cannot be improved.…”