Phenoxazinone synthase and antimicrobial activity by a bis(1,3-diamino-2-propanolate) cobalt(III) complex

• Published in: Journal of chemical sciences (Bangalore, India) Vol. 130; no. 12; pp. 1 - 12
• Main Authors: Chowdhury, Biswajit, Bhowmik, Biplab, Sahu, Amrita, Joshi, Mayank, Paul, Suvendu, Choudhury, Angshuman Roy, Biswas, Bhaskar
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 01.12.2018; Springer Nature B.V
• Subjects: Aminophenol; Bacteria; Binding; Bonding strength; Catalysis; Catalysts; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Chloride ions; Cobalt; Cobalt compounds; Coupling (molecular); Density functional theory; Organic chemistry; Oxygen; Quantum chemistry; Regular Article; Substrates; X ray spectra; Bio-mimicking Chemistry; DFT study; Phenoxazinone synthase activity; Cobalt(III); X-ray structure
• ISSN: 0974-3626; 0973-7103
• DOI: 10.1007/s12039-018-1562-9

In this work, we have synthesised and structurally characterized a mononuclear cobalt(III) complex, [ Co(2-O-pn) 2 ] Cl . 2H 2 O ( 1 ), (2-O-pn = 1,3-diamino-2-propanolate). From the X-ray structure of the cobalt complex, it is revealed that Co(III) ion in 1 adopts an octahedral geometry and crystallizes in the monoclinic system with C 2 /  c space group. The lattice aqua molecule in combination with chloride ion in 1 forms a water-chloride cluster, ( H 2 O ) 2 ⋯ (Cl) 2 through strong H-bonding interaction mediated via cobalt(III) complex in a unique binding motif. This cobalt(III) complex has been tested as an effective catalytic system towards the oxidative coupling of 2-aminophenol (2-AP) in the MeCN medium. In situ mass spectral analysis confirms that 2-AP forms an adduct with cobalt ion and the course of catalysis proceeds through catalyst-substrate binding followed by oxidative coupling of 2-AP with iminobenzoquinone. This cobalt(III) catalyst affords exclusively aminophenoxazinone species with a significant turnover number, k cat : 6.37 × 10 2 h - 1 in the MeCN medium. This cobalt(III) complex is able to screen out the growth of some bacteria and fungi species. Quantum chemical calculations employing density functional theory is used to model structural parameters and spectroscopic behaviour. The theoretical findings corroborate well with the experimental results. GRAPHICAL ABSTRACT SYNOPSIS A mononuclear cobalt(III) complex exhibits significant catalytic efficacy towards oxidative coupling of 2-aminphenol (2-AP) in MeCN medium and predominantly produces aminophenoxazinone species with a significant turn over number, k cat : 6.37 × 10 2 h - 1 in presence of molecular oxygen.