Dinuclear nickel complexes of divergent Ni⋯Ni separation showing ancillary ligand addition and bio-macromolecular interaction. (11th January 2016)

• Record Type: Journal Article
• Authors: Mahapatra, Tufan Singha; Chaudhury, Susmitnarayan; Dasgupta, Swagata; Bertolasi, Valerio; Ray, Debashis
• Is Part Of: New journal of chemistry. Volume 40:Number 3(2016:Mar.)
• Page Start: 2268
• Page End: 2279
• Publication Date: 2016-01-11
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/c5nj02410b
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : Reactions of ligand HL with nickel(ii ) salts produce a family of five [Ni2 ] complexes of varying co-ligand environments and intermetallic separations and show prominent interactions with HSA and CT-DNA. Abstract : Schiff base ligand HL has been utilized to build up a new family of five [Ni2 ] complexes, [Ni2 (μ-L)(μ-OH)](ClO4 )2 [1 (ClO4 )2 ], [Ni2 (μ-L)(μ-CF3 CO2 )2 (C3 H7 NO)(H2 O)]CF3 CO2 ·H2 O [2a (CF3 CO2 )·H2 O], [Ni2 (μ-L)(μ-CH3 CH2 CO2 )2 (C3 H7 NO)(H2 O)]ClO4 ·C3 H7 NO [2b (ClO4 )·C3 H7 NO], [Ni2 (μ-L)(μ-CH3 CO2 )(μ-NCS)(NCS)(C3 H7 NO)] (3a ) and [Ni2 (μ-L)(μ-CH3 CO2 )(μ-N3 )(N3 )(C3 H7 NO)] (3b ), in varying co-ligand environments. All the complexes have been characterized by elemental analyses, X-ray structure analysis and spectroscopic measurements. Three distinct types, dicationic, monocationic and neutral complexes, are synthesized using one pentadentate ligand HL. The Ni II centers are bridged by three sets of bridging groups resulting in a wide variation in Ni⋯Ni separations from 2.897 to 3.475 Å. Doubly bridged Ni II centers in the edge-shared square planar environment provide the shortest Ni⋯Ni separation in1 2+ . Whereas combination of other bridges from carboxylate, azide and isothiocyanate ancillary ligands results in cationic and neutral [Ni2 ] complexes2 + and3 having longer intermetallic separations. Modulation of Ni⋯Ni separation in synthetic complexes is fascinating in relation to the involvement and stabilization of the dinickel motif in the catalytic transition state of urease. Interaction and binding of cationic complexes (1–2b ) with human serum albumin (HSA) and calf thymus-DNA have been examined using spectroscopic techniques. Tryptophan fluorescence quenching of HSA by cationic bimetallic complexes (1, 2a and2b ) featuring a hydrophobic ligand environment shows spontaneous and favorable interactions in the order of2a >2b >1 . For the interaction study with CT-DNA, nearly planar complex1 binds more efficiently than2a and2b in octahedral coordination geometry.