Bioinspired catalysts for ROS scavenging and activation of small oxygenated molecules. Effect of immobilization on catalytic activity

SIGNORELLA, S. R.

Bento Gonçañves

Congreso; XX Brazilian Meeting on Inorganic Chemistry; 2022

Inspired by metal-biosites, a number of catalytic systems in which the metal can interact with small oxygenated molecules have been tested for biochemical, industrial and environmental purposes. In particular, Mn and Cu complexes of different nuclearity show a rich redox chemistry that can be modulated by the ligand and reaction conditions [1-3]. They have proven to be efficient scavengers of reactive oxygen species and can catalyze the oxidation of a variety of substrates. Besides, with suitable ligands it is possible to modulate the Mn+/M(n-1)+ redox potential and fulfill the requirement for a complex apt to promote O2 or H2O2 reactivity. However, in solution these catalysts often suffer solvolysis, metal dissociation or oligomerization. This pitfall can be overcome by covalent anchoring of the catalyst to a solid support or by its insertion inside a porous matrix. In this way, confinement and isolation of the metal center can avoid undesired interactions and improve the complex stability [4,5]. In particular, mesoporous silicas possess an ordered mesostructure with high specific area and pore volume and, consequently, high adsorption capability and are biocompatible at practical concentrations. The modulation of the pore size and the surface properties convert them in ideal materials for hosting molecules of different dimensions, shapes and functionalities. Therefore, the activity of the mimics can be further modulated by fine-tuning the properties of the solid matrix. In this talk, I described our recent results on the antioxidant activity and small molecules activation ability of several Mn and Cu biomimetic systems, and discussed key factors that control the redox processes when the catalysts are free and immobilized on a solid support.