Auxiliary Part of Ligand Mediated Unique Coordination Chemistry of Copper (II)

Abstract

Six N,N,O-donor Schiff-base ligands, HL1-HL6, [HL1/HL2/HL3= {2-(2-piperazin-1-yl)ethylimino)methyl)-4-(Cl/H/Me)-phenol}; HL4/HL5/HL6={2-(2-morpholine/piperidine/ pyrrolidine 1-yl)ethylimino)methyl)-4-chlorophenol}, have been designed by combining 5-R-2-hydroxy-benzaldehyde, (R=Cl/H/Me) and N-(2-aminoethyl)-Y, (Y=piperazin/morpholine/ piperidine/pyrrolidine) with the view to explore the role of R and X (part of Y excluding coordinating N) on the coordination chemistry of Cu (II) in presence of bromide as counter anion. HL1-HL6 formed in situ on reaction with Cu(II)Br2 produce complexes 1–6, respectively. Complex 1, [Cu(II)2Cu(I)2(L1)(MeOH)2Br7.30], is a mixed valence Cu(I)-Cu(II) species having phenyl ring brominated at ortho position with 0.65 occupancy. Complexes 2–4 are mononuclear species with general formula [Cu{L2/L3/L4)}Br2]. Complexes [Cu3(L5)Br4] (5) and [Cu3(L6)Br4] (6) are trinuclear species having similar structure but exhibit different magnetic property, 5 is ferro- (J= +16.64 cm1 ) and 6 is antiferromegnetic (J= –11.76 cm1). The influence of R and X on bromination, magnetic property and nuclearity issues have been rationalized by DFT calculations

Synthesis of Structurally Diverse Ferrimagnetically and Antiferromagnetically Coupled MII–MnII (M = Cu, Ni) Heterometallic Schiff Base Compounds with a Dicyanamide Spacer and Study of Biomimetic Catalytic Activity

“…In order to verify the oxidation state of compounds 1 and 2 in the solution phase, EPR studies were performed in MeOH and DMF media, respectively. From an EPR study (Figure S8), it was revealed that 1 has four EPR signals which are ascribed to Cu­(II). , Therefore, in the solution state the oxidation state of the manganese center of 1 exists as +3 (Mn­(III) is EPR silent). On the another hand, the six EPR spectral lines of 2 correspond to the Mn­(II) present in the solution phase.…”

Role of Electronegative Atom Present on Ligand Backbone and Substrate Binding Mode on Catecholase‐ and Phosphatase‐Like Activities of Dinuclear NiII Complexes: A Theoretical Support

“…[8] However, the role of auxiliary electronegative atom present in the amine part was not investigated over these catalytic processes. Our group has recently investigated the effect auxiliary atoms [9] in overall coordination chemistry in terms of structural and solid-state phenomenon but the effect on catalytic efficiencies have not been yet explored. These deficiencies therefore motivated us towards our current investigation.…”

Ligand‐Flexibility Controlled and Solvent‐Induced Nuclearity Conversion in CuII‐Based Catecholase Models: A Deep Insight Through Combined Experimental and Theoretical Investigations

“…Coordination complexes with different nuclearities are interesting for their potential application in different fields such as catalysis, modelling of metallobiosites, supramolecular chemistry, magnetochemistry etc Ligand flexibility, solvent, pH and anions are observed to be crucial factors in generating complexes with different nuclearity and structural diversity. Recently, by using flexible tridentate Schiff‐base ligands, we were able to synthesize complexes featuring different nuclearity, which exhibited quite different photophysical and/or biorelevant catalytic activities . Reduced Schiff bases have been attracting special interest from coordination chemists recently because of their greater flexibility over their Schiff base counterparts owing to the reduction of the more rigid azomethine (–CH=N–) fragment to the less constrained –CH 2 –NH– moiety .…”

“…Recently, by using flexible tridentate Schiff-base ligands, we were able to synthesize complexes featuring different nuclearity, which exhibited quite different photophysical and/or biorelevant catalytic activities. [4][5][6][7] Reduced Schiff bases have been attracting special interest from coordination chemists recently be-[a] Scheme 1. Synthetic routes to the complexes.the model substrate are important external contributors, [30][31][32][33][34] whereas Cu-Cu bond length, [35,36] stereoelectronic factors, [37,38] flexibility of the ligands and the coordination environment are the internal ones.…”

“…Recently, by using flexible tridentate Schiff-base ligands, we were able to synthesize complexes featuring different nuclearity, which exhibited quite different photophysical and/or biorelevant catalytic activities. [4][5][6][7] Reduced Schiff bases have been attracting special interest from coordination chemists recently be-[a] Scheme 1. Synthetic routes to the complexes.…”