Syntheses, Structures and Phenoxazinone Synthase Activities of Two Cobalt(III) Complexes

Mahato, Mamata; Mondal, Dipanjan; Nayek, Hari Pada

doi:10.1002/slct.201601597

Cited by 18 publications

(6 citation statements)

References 32 publications

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“…These values are listed in Table . The turnover numbers of both complexes are in the range of those of previously reported Co(III) complexes [19c, 22, 31] . Complex 2 , with a K cat value of 54.07 h −1 , exhibits better catalytic activity compared to 1 ( K cat = 45.11 h −1 ).…”

Section: Resultssupporting

confidence: 59%

“…We have also investigated the biological activity of the Ni(II)–Na(I) complex . In addition, we were able to show phenoxazinone synthase activities of two Co(III) complexes of H 2 L . In the work reported in the present contribution, we used the ligand H 2 L to synthesize two new mononuclear Co(III) complexes, [LCo(tmtp)(H 2 O)]ClO 4 ⋅MeOH ( 1 ) (tmtp = tri( m ‐tolyl)phosphine) and [LCo(PPh 3 )(H 2 O)]PF 6 ( 2 ) (PPh 3 = triphenylphosphine).…”

Section: Introductionmentioning

confidence: 99%

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Two mononuclear cobalt(III) complexes exhibiting phenoxazinone synthase activity

Mahato

Hecke

Nayek

2018

Applied Organom Chemis

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ClO 4 ⋅MeOH (1) (tmtp = tri(m-tolyl)phosphine) and [LCo(PPh 3 )(H 2 O)]PF 6 (2), have been prepared from a polydentate ligand, N,N′-bis(3methoxysalicylidehydene)cyclohexane-1,2-diamine (H 2 L). Standard analytical techniques such as elemental analysis and UV-visible and Fourier transform infrared spectroscopies were used to characterize both complexes. The solidstate molecular structures of both complexes were confirmed from single-crystal X-ray diffraction analysis. Structural analyses show that the Co(III) ion occupies the centre of a distorted octahedron in a complex cation: [LCo(tmtp) (H 2 O)] + and [LCo(PPh 3 )(H 2 O)] + for 1 and 2, respectively. Phenoxazinone synthase activities of both complexes were screened. Kinetic studies and other experimental observations reveal that the reaction follows rate saturation kinetics and proceeds through the formation of a catalyst (complex)-substrate adduct. The turnover number (K cat ) of complex 2 is 54.07 h −1 , exhibiting better catalytic activity compared to 1 (K cat = 45.11 h −1 ). KEYWORDS cobalt(III) complex, phenoxazinone synthase activity, Schiff base, single-crystal X-ray diffraction, turnover number | INTRODUCTIONSchiff bases cover an enormous area in coordination chemistry predominantly due to their smooth synthesis, controllability of steric and electronic environment and diversity in applications. [1] Schiff bases can easily accommodate single or multiple metal ions of various oxidation states. [2] Judicial selection of Schiff bases and metal ions often results in homo-or heteronuclear metal complexes including those of transition metals and main group elements. [3] Depending on the nature of the ligands and metal ions, these complexes exhibit structural diversities and open up applications in several areas such as biology, [4] catalysis, [5] materials science [6] and magnetism. [7] Interestingly, salen-type ligands, which are prepared from various diamines and salicylaldehyde derivatives, are most widely explored among all Schiff bases in coordination chemistry. [8] Modification of salicylaldimine ligands, for example by anchoring a methoxy group (-OMe) on the salicylaldimine moiety, increases their denticity making the ligands more prone to form polynuclear complexes. [9] Numerous examples of metal complexes of Schiff base ligands have been reported in the literature. However, metal complexes containing cobalt(II/III) ions have recently started to receive attention. [10] Cobalt(II/ III) complexes of Schiff base ligands find important applications in magnetism, [11] biochemistry [12] and catalysis. [13] These complexes have been used in mimicking important biological co-factors such as phenoxazinone synthase, [14] photosynthesis, [15] methionine aminopeptidase, [16] cobalamin, etc. Among these, phenoxazinone synthase facilitates the conversion of o-aminophenol

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Section: Resultssupporting

confidence: 59%

Section: Introductionmentioning

confidence: 99%

Two mononuclear cobalt(III) complexes exhibiting phenoxazinone synthase activity

Mahato

Hecke

Nayek

2018

Applied Organom Chemis

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“…The activity of 1 as a phenoxazinone synthase mimic was examined by UV/Vis spectrophotometry with o ‐aminophenol (OAP) as the substrate . Firstly, it was important to check whether the present complex could catalyze the oxidation of OAP under aerobic conditions.…”

Section: Resultsmentioning

confidence: 99%

Valence‐Tautomerism‐Driven Aromatic Nucleophilic Substitution in Cobalt‐Bound Tetrabromocatecholate Ligands – Influence of Positive Charge at the Ligand Backbone on Phenoxazinone Synthase Activity

Panja¹,

Frontera

2018

Eur J Inorg Chem

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The mononuclear Co III complex [Co(Br 3 Cat-py) 2 (py) 2 ]-Cl·8H 2 O (1, py = pyridine, Br 3 pyCatH 2 = 3,5,6-tribromo-4-pyridiniumcatechol) was synthesized through the reaction of CoCl 2 ·6H 2 O with tetrabromocatechol in the presence of an excess of pyridine at elevated temperature. The solid-state structure was determined by X-ray crystallography, which disclosed the valence-tautomerism-induced aromatic nucleophilic substitution of the tetrabromocatecholate ligands by pyridine. A cyclic voltammetry study revealed the redox flexibility of both the transition-metal centre and the coordinated redox-active ligand in this complex. Moreover, 1 exhibits moderately strong catalytic activity and mimics the function of phenoxazinone [a] Postgraduate

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“…Various bioinspired models have been studied owing to the availability of literature reports on the structural and functional properties of PHS. 23,28–35 A tetranuclear cubane-like Cu( ii ) core was first reported by Chaudhuri and co-workers that could catalyze the oxidation of H 2 AP to APX in the presence of molecular oxygen. 28 A few more tetranuclear centres were later reported as the possible mimics of PHS.…”

Section: Introductionmentioning

confidence: 99%

“…31 In addition, several mononuclear compounds were reported to mimic PHS property. In this respect, not only Cu 32 but other metals like Mn, 33 Fe, 34 and Co 35 have been used to prepare mononuclear mimics of PHS.…”

Section: Introductionmentioning

confidence: 99%

Structure–function correlation of mononuclear nonheme copper(ii) compounds based on a ligand backbone effect and phenoxazinone synthase activity

et al. 2023

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Syntheses, Structures and Phenoxazinone Synthase Activities of Two Cobalt(III) Complexes

Cited by 18 publications

References 32 publications

Two mononuclear cobalt(III) complexes exhibiting phenoxazinone synthase activity

Two mononuclear cobalt(III) complexes exhibiting phenoxazinone synthase activity

Valence‐Tautomerism‐Driven Aromatic Nucleophilic Substitution in Cobalt‐Bound Tetrabromocatecholate Ligands – Influence of Positive Charge at the Ligand Backbone on Phenoxazinone Synthase Activity

Structure–function correlation of mononuclear nonheme copper(ii) compounds based on a ligand backbone effect and phenoxazinone synthase activity

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