Article ID Journal Published Year Pages File Type
1335508 Polyhedron 2014 10 Pages PDF
Abstract

Two new dinuclear copper(II) and zinc(II) complexes of an isoindol functionality based new dinucleating ligand, H3hdpa (H3hdpa = 2-({[2-hydoxyethyl]-[2-hydroxy-3-(1-oxo-1,3-dihydro-isoindol-2-yl)-propyl]-amino}-methyl)-benzoic acid) have been synthesized and characterized. In methanol, the reaction of stoichiometric amounts of Cu(OAc)2·H2O and the ligand H3hdpa in the presence of NaOH at ambient temperature afforded a new dinuclear copper(II) complex, [Cu2(Hhdpa)2]·2CH3OH·6H2O (1). Similarly, in methanol, the reaction of stoichiometric amounts of Zn(OAc)2·2H2O and H3hdpa in the presence of NaOH yielded a new dinuclear zinc(II) complex, Na4[Zn2(hdpa)2](OAc)2 (2). Characterization of the complexes has been performed using various analytical techniques, including single crystal X-ray structure determination. The X-ray crystal structure of complex 1 reveals that two copper(II) centers adopt a five-coordinate square pyramidal geometry with a Cu–Cu separation of 2.910 Å. The DFT optimized structure of complex 2 shows that two zinc(II) centers are in a distorted trigonal bipyramidal geometry with a Zn–Zn separation of 3.124 Å. 1H and 13C NMR spectroscopic investigations authenticate the integrity of complex 2 in solution. Further, the mass spectroscopic analyses of complexes 1 and 2 reconfirm their dimeric nature, even in solution. Variable-temperature (2–300 K) magnetic susceptibility measurements show the presence of antiferromagnetic interactions (J = −52.20 cm−1) between the two copper(II) centers in complex 1. The catechol oxidase activity of complexes 1 and 2 has been investigated in methanol medium by the UV–Vis spectrophotometric technique using 3,5-di-tert-butylcatechol as a model substrate. Both complexes are active in catalyzing the aerobic oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butyl-1,2-benzoquinone (3,5-DTBQ). A DFT calculation has been performed to find the Fukui functions at the metal centers in complexes 1 and 2 to predict the possible metal centers involved in the binding process with 3,5-DTBC during the catalytic oxidation reactions.

Graphical abstractTwo new dinuclear copper(II) and zinc(II) complexes, [Cu2(Hhdpa)2]·2CH3OH·6H2O (1) and Na4[Zn2(hdpa)2](OAc)2 (2), of an isoindol functionality based new dinucleating ligand, H3hdpa (H3hdpa = 2-({[2-hydoxyethyl]-[2-hydroxy-3-(1-oxo-1,3-dihydro-isoindol-2-yl)-propyl]-amino}-methyl)-benzoic acid), have been synthesized and characterized. Variable-temperature (2–300 K) magnetic susceptibility measurements show the presence of antiferromagnetic interactions (J = −52.20 cm−1) between the two copper(II) centers in complex 1. Catechol oxidase activity of complexes 1 and 2 has been investigated in methanol solution by the UV–Vis spectrophotometric technique using 3,5-di-tert-butylcatechol as a model substrate. DFT calculations have been performed to find the Fukui functions at the metal centers in complexes 1 and 2 to predict the possible metal centers involved in the binding process with 3,5-DTBC during the catalytic oxidation reactions.Figure optionsDownload full-size imageDownload as PowerPoint slide

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Physical Sciences and Engineering Chemistry Inorganic Chemistry
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