title: Ligand centered radical pathway in catechol oxidase activity with a trinuclear zinc-based model: synthesis, structural characterization and luminescence properties.
abstract: A new trinuclear zinc(II) complex, [Zn3(L)(NCS)2](NO3)2·CH3OH·H2O (1), of a (N,O)-donor compartmental Schiff base ligand (H2L=N,N'-bis(3-methoxysalicylidene)-1,3-diamino-2-propanol), has been synthesized in crystalline phase. The zinc(II) complex has been characterized by elemental analysis, IR spectroscopy, UV-Vis spectroscopy, powder X-ray diffraction study (PXRD), (1)H NMR, EI mass spectrometry and thermogravimetric analysis. PXRD revealed that 1 crystallizes in P-1 space group with a=9.218 Å, b=10.849 Å, c=18.339 Å, with unit cell volume is 2179.713(Å)(3). Fluorescence spectra in methanolic solution reflect that intensity of emission for 1 is much higher compared to H2L and both the compounds exhibit good fluorescence properties. The complex 1 exhibits significant catalytic activities of biological relevance, viz. catechol oxidase. In methanol, it efficiently catalyzes the oxidation of 3,5-di-tert-butylcatechol (3,5-DTBC) to corresponding quinone via formation of a dinuclear species as [Zn2(L)(3,5-DTBC)]. Electron Paramagnetic Resonance (EPR) experiment suggests generation of radicals in the presence of 3,5-DTBC and it may be proposed that the radical pathway is probably responsible for conversion of 3,5-DTBC to 3,5-DTBQ promoted by complex of redox-innocent Zn(II) ion.
authors.affiliation: Department of Chemistry, Raghunathpur College, Purulia 723133, India.
authors.forename: Sukanta
authors.initials: S
authors.lastname: Pal
authors.affiliation: Department of Chemistry, Raghunathpur College, Purulia 723133, India.
authors.forename: Biswajit
authors.initials: B
authors.lastname: Chowdhury
authors.affiliation: Department of Physics, Raghunathpur College, Purulia 723133, India.
authors.forename: Moumita
authors.initials: M
authors.lastname: Patra
authors.affiliation: Department of Chemistry, National Institute of Technology, Durgapur 713209, India.
authors.forename: Milan
authors.initials: M
authors.lastname: Maji
authors.affiliation: Department of Chemistry, Raghunathpur College, Purulia 723133, India. Electronic address: icbbiswas@gmail.com.
authors.forename: Bhaskar
authors.initials: B
authors.lastname: Biswas
mesh_terms: D004156:Catechol Oxidase / Q000378:metabolism*; D002396:Catechols / Q000737:chemistry / Q000378:metabolism; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry* / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D007700:Kinetics; D008024:Ligands; D049449:Luminescence; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011208:Powders; D012996:Solutions; D012997:Solvents; D013050:Spectrometry, Fluorescence; D013818:Thermogravimetry; D014961:X-Ray Diffraction; D015032:Zinc / Q000378:metabolism*
chemical_list: D002396:Catechols; D056831:Coordination Complexes; D008024:Ligands; D011208:Powders; D012996:Solutions; D012997:Solvents; C054068:3,5-di-tert-butylcatechol; D004156:Catechol Oxidase; D015032:Zinc
keywords: Catecholase activity; Electron paramagnetic resonance; Fluorescence; Schiff base; Zinc(II)