The standard molar enthalpy of formation of a new copper(II) Schiff-base complex and its interaction with bovine serum albumin

• A new copper(II) Valen Schiff-base complex was synthesized and characterized.
• The standard molar enthalpy of formation of the title complex was obtained.
• The interaction between the complex and bovine serum albumin was investigated.

A new copper(II) Schiff-base complex [Cu(HL)·NO3·MeOH] was prepared by using equivalent molar of Valen Schiff-base ligand [H2LN,N′-ethylene-bis(3-methoxysalicylideneimine)] and Cu(NO3)2·3H2O. The structure of the complex was confirmed by single-crystal X-ray diffraction. Based on an ideal and feasible thermochemical cycle, the standard molar enthalpy of formation of the complex was estimated to be: ΔfHmθ [Cu(HL)·NO3·MeOH(s), 298.15 K] = –(945.40 ± 2.44) kJ mol−1 by an advanced solution-reaction isoperibol calorimeter. In particular, the interaction between the complex and bovine serum albumin (BSA) was investigated using the fluorescence quenching method. Fluorescence quenching data showed that the quenching mechanism of BSA treated by the complex was static quenching, which was highly accord with the non-radioactive energy transfer theory. And some relevant parameters such as binding sites, binding distance and intermolecular forces between the complex and BSA were also obtained by analyzing the fluorescence spectral data.