The electrochemical properties of diazophenylcalix[4]arenes bearing ortho-carboxyl group (o-CAC) and ortho-ester group (o-EAC), respectively, in the presence of various metal ions were investigated by voltammetry in CH3CN. o-CAC and o-EAC showed voltammetric changes toward divalent metal ions and no significant changes with monovalent alkali metal ions. However, o-CAC preferentially binds with ...

Fructose-1,6-bisphosphatase (Fru-1,6-Pase; D-fructose-1,6-bisphosphate 1-phosphohydrolase, EC 3.1.3.11) requires two divalent metal ions to hydrolyze alpha-D-fructose 1,6-bisphosphate. Although not required for catalysis, monovalent cations modify the enzyme activity; K+ and Tl+ ions are activators, whereas Li+ ions are inhibitors. Their mechanisms of action are still unknown. We report here cr...

this study examines the effects of change in the concentrations of monovalent and divalent ions in the polymer-contained surfactant solution on the macroscopic behavior of viscous-modified surfactant waterflooding in heavy oil reservoirs. salts that are used in this set of floods were sodium chloride, magnesium chloride, and calcium chloride. the results indicate that four different ranges of s...

SalNa (sodium salinomycin) reacts with divalent transition metal ions of Co(II), Ni(II), Cu(II) and Zn(II) to produce novel compounds characterized by various spectroscopic methods. The interaction of metal (II) ions with SalNa results in the formation of mononuclear complexes of a general composition of [M(Sal)2·(H2O)2] nH2O (n = 0 or 2) where the divalent cations replace Na ions from the cavi...

In recent years, numerous computer simulations have been performed on aqueous solutions of monovalent and divalent metal ions. Monte Carlo (MC) and/or Molecular Dynamics (MD) simulations [1] have been reported for example on LiCl [2], NaCl [3], BeCl2 [4], MgCl2 [5], CaCl2 [6] and SrCl2 [7] solutions dealing with the structure of the hydration shell of the ions and spectroscopic data for the ion...

The DNA cleavage reaction of human topoisomerase IIalpha is critical to all of the physiological and pharmacological functions of the protein. While it has long been known that the type II enzyme requires a divalent metal ion in order to cleave DNA, the role of the cation in this process is not known. To resolve this fundamental issue, the present study utilized a series of divalent metal ions ...

A series of dinuclear complexes of a pseudocalixarene macrocycle H6L containing two 2,2'-methylenediphenol groups have been synthesised and structurally characterised. Using divalent metal ions, complexes containing a common hyperbolic paraboloid (saddle) M2(H4L)2+ core are formed. The structure is controlled by two strong O-H-O interactions resulting from metal ion-promoted monodeprotonation o...

Some new complexes of thiacetazone (Thz) and quinalizarin (Qz) with Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) were prepared. The ligands and their metal complexes were characterized by phisco-chemical spectroscopic techniques. The spectral data suggested that the thiacetazone as a neutral bidentate ligand is coordinated with the metal ions through the N and S atoms. The ...

The aim of this work was to construct chemical models for selective hydrolysis of phosphate monoesters in order to elucidate the role of metal ions in the hydrolytic mechanisms and to develop artificial enzymes for practical applications. A dinuclear copper(II) complex of a cyclohexane-based polyamino polyalcohol provided a selective and by far the highest rate acceleration among the transition...