Impact of transition metals (M=Mn, Fe, Co, Ni, Cu, Zn) on the formation of local and crystal structure of MBTC phases

Abstract

In this work, the results of studying the composition (bulk and surface), structure (crystal and local) and biocidal properties of metal-organic frameworks (MOFs) based on benzene-1,3,5-tricarboxylic acid (H₃BTC), called MBTC (M = Fe, Mn, Co, Ni, Cu, Zn; M²⁺Cl₂·4H₂O precursor), obtained by a hydrothermal method under the same process conditions were presented. XRPD, XAS, XPS, SEM, and FTIR methods were used. The formal charge (FC) was determined for Fe³⁺, Cu²⁺ (Jahn-Teller ion), Zn²⁺ and, for the first time, a mixed FC was determined for Co^(3,2)+, Ni^(3,2)+ and Mn^(3,2)+ (with a higher content of Mn³⁺ Jahn-Teller ions). It was shown that in the M - BTC system, depending on FCM, MOFs with different types of structures are formed (MIL-100 with Fe, sp. gr. Fd3m; HKUST-1 with Cu, sp. gr. Fm3m; MBTC with M = Mn, Co, Ni, sp. gr. P $\bar{3}$; MBTC with Zn, sp. gr. C2), in which the coordination environment of M ions is different. The results obtained made it possible to divide MOF structures into 4 groups depending on the nature of the М metals. This allows predicting the topological structural types of MBTC based on the electronic structure of М ions. The results of studying the antimicrobial activity of MBTCs indicate a possible connection between the biocidal properties of bacteria and the electronic structure of M.