Synthesis, crystal structure, magnetic, DSS cell, lifetime measurement, electrochemical, catecholase activity, and antimicrobial studies of mono and hetero binuclear cryptates

Mono and hetero binuclear cryptates, [GdML(DMF)] [M = VO(IV), Co(II), Cu(II)], were synthesized. The ligand L represents the deprotonated anionic cryptate obtained by the 2+3 condensation of tris-(2-aminoethyl)amine with 2,6-diformyl-4-methylphenol. The crystal structure of [GdL(NO₃)](NO₃)₂·H₂O was determined by single-crystal X-ray diffraction method. The magnetic susceptibility of the complexes was measured by SQUID. The Gd(III)Cu(II) cryptate has ferromagnetic interaction and [Gd(III)VO(IV)] cryptate has weaker intramolecular antiferromagnetic interaction. Fluorescence intensity and excited state lifetime of the cryptates increase in the following order: [GdCoL] < [GdVOL] < [GdL] < [GdCuL]. The efficiency (η) of cryptate based dye-sensitized solar cell increases in the following order: [GdL] < [GdVOL] < [GdCoL] < [GdCuL]. The reduction potential values of [Gd(M)L] M = VO(IV), Co(II), Cu(II) complexes are in the following order: Cu(II) > Co(II) > VO(IV). The catecholase activity of binuclear [GdML] complexes are relatively high compared with the mononuclear [Gd(III)L] complex in the following order: [GdL] < [GdVOL] < [GdCoL] < [GdCuL]. The antimicrobial activity of the binuclear complex Gd(III)Cu(II) is relatively higher than the mononuclear and other binuclear complexes.     

Characterization and Reactivity of a Tetrahedral Copper(II) Alkylperoxido Complex

A tetrahedral Cu^II alkylperoxido complex [Cu^II(TMG₃tach)(OOCm)]⁺ ( 1^OOCm ) (TMG₃tach={2,2′,2′′-[(1s,3s,5s)-cyclohexane-1,3,5-triyl]tris-(1,1,3,3-tetramethyl guanidine)}, OOCm=cumyl peroxide) is prepared and characterized by UV/Vis, cold-spray ionization mass spectroscopy (CSI-MS), resonance Raman, and EPR spectroscopic methods. Product analysis of the self-decomposition reaction of 1^OOCm in acetonitrile (MeCN) indicates that the reaction involves O−O bond homolytic cleavage of the peroxide moiety with concomitant C−H bond activation of the solvent molecule. When an external substrate such as 1,4-cyclohexadiene (CHD) is added, the O−O bond homolysis leads to C−H activation of the substrate. Furthermore, the reaction of 1^OOCm with 2,6-di-tert-butylphenol derivatives produces the corresponding phenoxyl radical species (ArO^.) together with a Cu^I complex through a concerted proton-electron transfer (CPET) mechanism. Details of the reaction mechanisms are explored by DFT calculations.