Structure and synthesis of copper-based Schiff base and reduced Schiff base complexes: a combined experimental and theoretical investigation of biomimetic catalytic activity. Issue 43 (3rd November 2020)

• Record Type: Journal Article
• Authors: Mandal, Arnab; Sarkar, Abani; Adhikary, Amit; Samanta, Debabrata; Das, Debasis
• Is Part Of: Dalton transactions. Volume 49:Issue 43(2020)
• Page Start: 15461
• Page End: 15472
• Publication Date: 2020-11-03
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d0dt02784g
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : A DFT-based mechanistic study of phosphatase and phenoxazine synthase activities of Schiff base and reduced Schiff base complexes. Abstract : Three copper(ii ) complexes, [Cu(L 1 )(NCS)] n (1 ), [Cu(L 1 )(N3 )] n (2 ) and [Cu(L 2 )(N3 )] (3 ) were synthesized from one Schiff base ligand and one reduced Schiff base ligand, ( E )-4-chloro-2-[(2-propylaminoethylimino)methyl]phenol (HL 1 ) and 4-chloro-2-[(2-(propylaminoethylamino) methyl]phenol (HL 2 ), respectively. All complexes were characterized by various physicochemical studies, such as FT-IR, UV-Vis, ESI-MS, EPR and single crystal X-ray diffraction. Complexes 1 and 2 have 1D polymeric chain-like structures bridging through thiocyanate and azide anions, whereas complex 3 has a mononuclear structure in the solid state. All the complexes are active towards mimicking two well-known proteins, phosphatase and phenoxazinone synthase, using the disodium salt of 4-nitrophenylphosphate (4-NPP) and 2-aminophenol (OAP) as the substrate in DMF medium. Complexes 2 and 3 show the highest activity towards phosphatase and phenoxazinone synthase activity with k cat values of 22.6 s −1 and 134.4 h −1, respectively. EPR studies confirmed that for complex 1, the OAP oxidation goes through the generation of an organic radical at g = 1.99, which is due to an imine radical formation, whereas the metal center redox pathway is followed for complex 3 . Extensive DFT calculations have been performed for both catalytic studies to put forward the most probable mechanistic pathways.