Effect of structural variation on enzymatic activity in tetranuclear (Cu₄) clusters with defective cubane core

The stimulus to the modeling of enzyme functioning sites comes from their potential to give insight into the natural enzyme's mechanistic pathways, ascertain the role of that different metal ion in the active site and construct better catalysts motivated by nature. The presence of metal ion leads to the activation of molecular oxygen in the metalloenzymes. The metalloenzymes such as the catechol oxidase (CO) enzyme that oxidizes the catechol to corresponding quinones which eventually protect damage tissues from plant and pathogen. Thus, the design and characterization of catalysts used as selectively and efficiently oxidation reactions have grown to be unique challenges for modern inorganic chemists. In this work, two novel tetranuclear complexes (1 and 2) have been synthesized in excellent yield. The complexes were characterized using various spectroscopic techniques such as FTIR, UV-Visible and PXRD pattern. The structure of 1 and 2 was elucidated by SC-XRD (single crystal X-ray diffraction) analysis. The magnetic study reveals the presence of the antiferromagnetic nature of 1 and 2. Both 1 and 2 shows a very good catecholase-like activity by oxidizing the catechol to analogous quinone in methanolic solution. Thus, a structure-activity relationship can further help us design other substituted tetranuclear complexes with enhanced catecholase like activity.Communicated by Ramaswamy H. Sarma.