High-Throughput Approach for Facile Access to Hetero-Dinuclear Synergistic Metal Complex for H 2 O 2 Activation and Its Implications.

Hetero-dinuclear synergic catalysis is a promising approach for improving catalytic performance. However, employing it is challenging because the design principles for the metal complex are still not well understood. Further, these complexes have a broader set of possibilities than mononuclear or homometallic systems, increasing the time and effort required to understand them. In this study, we explored a high-throughput approach to obtain a new hetero-dinuclear synergistic metal complex for H 2 O 2 activation. From the 1152 combinations of metal complex candidates obtained by changing three variables (metal ions, unsymmetrical dinucleating ligands, and pH), the lead complex ( L3 -(Ni, Co)), which has the highest peroxidase activity, was derived using colorimetric parallel analysis. A series of control experiments revealed that L3 plays a crucial role in the formation of active L3 -(Ni, Co) complexes, Co 2+ acts as a catalytic center, and Ni 2+ serves as an assistant catalytic site within L3 -(Ni, Co). In addition, the catalytic efficiency of L3 -(Ni, Co), which was 125 times that of the homo-bimetallic complex ( L3 -(Co, Co)), revealed clear hetero-bimetallic synergism in the buffer. The ultraviolet-visible study and electron paramagnetic resonance-based spin-trap experiment provided mechanistic insight into H 2 O 2 activation by the intermediate, which was found to be induced by the reaction of L3 -(Ni, Co) and H 2 O 2 . Moreover, the intermediate could act as a donor of the hydroperoxyl radical ( • OOH) in the buffer. Furthermore, L3 -(Ni, Co) demonstrated potential for application as a signal transducer for H 2 O 2 in an enzyme-coupled cascade assay that can be used for the colorimetric detection of glucose.