SYNTHESIS AND PRACTICAL APPLICATION OF IMMOBILIZED VANADIUM(IV) COMPLEXES WITH SCHIFF BASES

Data on methods for the synthesis of immobilized vanadium(IV) coordination compounds with Schiff bases on various solid supports, such as silica (silica gel, mesoporous silicas, non-porous nanosilicas), graphene oxide, magnetic nanoparticles, clay matrices, zeolites, polymers, biopolymers are systematized in this article. In particular, the potential of various forms of dispersed silicon dioxides as carriers has been identified due to their ability for covalent immobilization of vanadium complexes, thermal stability, and applicability in different environments. Specifically, macro- and mesoporous silicas provide a large surface area and a well-ordered pore structure, enabling their successful use in continuous flow catalytic processes. Examples of the use of such immobilized vanadium(IV) Schiff base complexes as heterogeneous catalysts, corresponding to modern concepts of green chemistry, in oxidation reactions of sulfides, thiols, alcohols, alkenes, phenols, furfurals; in hydroamination and oxidative amination reactions, oxidative halogenation, functionalization of alkenes, hydroxylation of alkanes, in asymmetric synthesis and other reactions of importance for the chemical and pharmaceutical industries and ecology are given. The chemism and conditions for the occurrence of some of these reactions are presented. The advantages of heterogeneous catalysts – immobilized vanadium complexes with Schiff bases – compared to homogeneous analogues are shown, namely: high catalytic activity and selectivity under mild conditions, stability, easy separation and reusability. Thus, these heterogeneous catalysts demonstrate promise for industrial application. The prospect of using immobilized vanadium complexes with Schiff bases in biomedicine and for electrochemical applications is also shown.