Dicopper Double-Strand Helicates Held Together by Additional π–π Interactions

Synthesis, crystal structure, photoluminescence and catalytic properties of a novel cuprous complex with 2,3-pyrazinedicarboxylic acid ligands

A copper (I) polymer, [Cu2Mg(pzdc)2(H2O)5•2H2O]n (pzdc = 2,3-Pyrazinedicarboxylic acid), was synthesized by solvothermal method. The complex was characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectrophotometry (UV-Vis), and element analysis. X-ray crystal structure analysis reveals that the complex is a two-dimensional coordination polymer. The photophysical and luminescent properties of the complex were investigated. At room temperature, the complex exhibits reversible double strands cyclic voltammogram and displays efficient blue emission with peak maxima at 468 nm. Catalytic liquid phase oxidation of dyes and glyphosate was carried out using the copper (I) polymer as catalyst and H2O2 as oxidant. Degradation efficiencies were evaluated by varying the reaction conditions (i.e. illumination and oxidant). In the degradation reactions, the polymer exhibits high degradation efficiency within a short reaction time under the optimum reaction conditions. Furthermore, the reusability of the catalyst is excellent, showing no activity loss in four repeated cycles. The possible reaction mechanism catalyzed by the polymer was inferred on the basis of the results of electron spin resonance (ESR), electrochemical and ion chromatography analyses (IC).

Double-stranded dimetallic helicates: assembling-disassembling driven by the Cu(I)/Cu(II) redox change and the principle of homochiral recognition

In the presence of d(10) metal ions, prone to tetrahedral coordination, ligands containing two bidentate subunits will give rise to double-stranded helical complexes (helicates). Upon electrochemical oxidation of Cu(I) to Cu(II), the helicate complex tends to disassemble, thus giving rise to two mononuclear Cu(II) complexes with tetragonal geometry. Upon subsequent Cu(II)-to-Cu(I) electrochemical reduction, two Cu(I) complexes instantaneously re-assemble to give the helicate complex. A helicand containing a chiral subunit (e.g. 1,2-substituted cyclohexanediamine) contains a racemic mixture of the R,R and S,S enantiomers. The racemic helicand, reacting with Cu(I), forms dimetallic helicates, in which the two strands show the same chirality, whether R,R or S,S, thus obeying the principle of homochiral recognition.