Mononuclear manganese(iii) complexes of bidentate NO donor Schiff base ligands: synthesis, structural characterization, magnetic and catecholase studies

Abstract

We have synthesized four mononuclear manganese(iii) complexes (1–4) of four closely related bidentate NO donor Schiff-base ligands, out of which three (2–4) were structurally characterized.

A new mononuclear Fe(iii) Mannich-base complex with selective histidine binding and catechol oxidase activity

“…32 The higher energy absorbances are observed at 298, 247, and 212 nm regions corresponding to intraligand n → π* and π → π* electronic transitions, respectively. 33…”

Catecholase Activity of a Mn(III) Complex: An Approach through1H‐NMR spectroscopy

“…The turnover numbers can vary from low to moderate to high. For Mn(II) complexes, k cat varies in the range 11.88–3.10×10 6 h −1[13,6a,] while for Mn(III) complexes k cat values range from 7.33×10 −7 to 1.25×10 5 h −1 [5,8b,10,14a–e] . Mixed valent (Mn(II)‐Mn(III)) and Mn(IV) systems show the turnover numbers in between 255 and 9011 h −1 [15]…”

Introducing Supramolecular Interactions into Robust Bis(tetrabromocatecholate) Chelated Manganese(III) Systems and Biomimetic Catalytic Activity

“…The rate saturation kinetics clearly support the formation of a stable complex‐substrate aggregate prior to the production of 3,5‐DTBQ. The mechanistic pathways of functioning catecholase activity of such manganese(III) complexes are well explored, and the direct redox participation of manganese(III) was suggested in most cases . To get insight into the mechanistic pathway through which the present complexes exhibit catecholase activity, the UV−vis spectra of the complex by itself and in the presence of excess substrate were recorded.…”

“…The latter is a dicopper metalloenzyme, the function of which is the oxidation of a wide range of o ‐diphenols (catechols) to the corresponding o ‐quinones, which undergo auto‐polymerization to produce a brown pigment melanin as a natural antiseptic to protect the damaged tissues against both bacterial and fungal diseases . Whereas several mono‐ and multinuclear copper complexes have been found to be successful models for such metalloenzymes,, functional models with other transition metals have been limited, and thus need further attention …”