High phenoxazinone synthase activity of two mononuclear cis-dichloro cobalt(ii) complexes with a rigid pyridyl scaffold

Muley, Arabinda and Karumban, Kalai Selvan and Kumbhakar, Sadananda and Giri, Bishnubasu and Maji, Somnath (2022) High phenoxazinone synthase activity of two mononuclear cis-dichloro cobalt(ii) complexes with a rigid pyridyl scaffold. New Journal of Chemistry, 46 (2). pp. 521-532. ISSN 1144-0546

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Abstract

Phenoxazinone synthase (PHS) is a pentanuclear copper enzyme studied for the last two decades, and though both manganese and copper complexes have been explored extensively, there are only a handful of reports on cobalt mononuclear moieties. In this regard, we have successfully synthesized two cis dichloro cobalt(ii) mononuclear complexes Co(bpy)2Cl2:[1] and Co(L1)2Cl2:[2] with polypyridyl ligands (where bpy = 2,2′-bipyridine, L1 = 2,2′-(1-methyl-1H-1,2,4-triazole-3,5-diyl)dipyridine) and thoroughly characterized them by different spectroscopic and analytical techniques such as FT-IR, 1H NMR, UV-vis spectroscopy and ESI mass spectra. The molecular structures of [1] and [2] are elucidated by single-crystal X-ray diffraction studies. Spectral properties and redox behaviour for both the complexes are examined. The complexes show phenoxazinone synthase activity under ambient conditions and thorough examination of the acquired spectroscopic data imply excellent reactivity for both. Kinetic parameters for both the complexes are evaluated and the turnover numbers (kcat value) of these two complexes are 201.24 h-1 and 249.57 h-1 for [1] and [2], respectively, which are quite high compared to those of previously reported similar complexes. The possible mechanistic route is also established with the help of mass spectroscopy and titrimetric analysis is performed to detect hydrogen peroxide that is a key intermediate formed in the catalysis and thus to prove the involvement of molecular oxygen in the oxidation. This report offers an in-depth summary of metal ion involvement and the extent of the phenoxazinone synthase activity. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.

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IITH Creators:

IITH Creators	ORCiD
Maji, Somnath	http://orcid.org/0000-0001-6047-1339

Item Type:

Article

Additional Information:

Financial support received from Science and Engineering Research Board (SERB), Department of Science and Technology, India: project no. ECR/2016/000382; Council of Scientific and Industrial Research (CSIR) (fellowships to A. M., K. S. and B. G.) and Indian Institute of Technology, Hyderabad is gratefully acknowledged. Special thanks go to Dr Jai Prakash for helpful crystallographic discussion.

Uncontrolled Keywords:

Co(bpy); Cobalt complexes; Copper complexes; Manganese complexes; Mononuclear complexes; Pentanuclear; Polypyridyl ligands; Pyridyl; Synthases; Synthesised

Subjects:

Chemistry

Divisions:

Department of Chemistry

Depositing User:

. LibTrainee 2021

Date Deposited:

15 Jul 2022 06:42

Last Modified:

15 Jul 2022 06:42

URI:

http://raiithold.iith.ac.in/id/eprint/9728