Catecholase-like activity in 2D MOFs: Oxidation of 3,5-DTBC by two Cu(II) 2D MOFs of reduced Schiff base ligands

Abstract Two-dimensional metal-organic frameworks (2D MOFs) materials have been explored extensively for their interesting properties and applications, but not so much for Catecholase-like catalytic activity. We describe here two Cu(II) 2D MOFs of reduced Schiff base ligands for their Catecholase-like activity. These were synthesized and characterized by spectroscopic analyses. The solid state structure of [Cu2(NglyR)2] (where NglyR is a reduced Shiff base ligand derived from 2-hydroxy-1-naphthaldehyde and glycine) (1) consistes of two Cu(II) atoms bridged by two phenalato groups and further chelated by oxygen and nitrogen atoms of the glycine part of NglyR ligand. These dimers are further linked by the terminal carboxylato oxygen atoms to possess a 2D sheet structure. In the absence of solid-state structure of [Cu2(NSchR)2] (2) (where NSchR is a reduced Schiff base ligand derived from 2-hydroxy-1-naphthaldehyde and 1-amino-1-cyclohexanecarboxylic acid), the dinuclear core with bridging phenolate ligands has been proposed from physicochemical and spectroscopic methods. The MOFs have also been investigated for their catecholase-like activities with 3,5-di-tert-butylcatechol (3,5-DTBC). Hyperbolic inhibition was observed for 1 in the following solvent systems: MeOH, MeOH:DMF (95:5, v/v) and (90:10, v/v), but not for 2. Moreover, catalytic activities are found to be heavily influenced by v/v ratio of the mixed solvent systems and solvent nucleophilicity.