Synthesis and Crystal Structure of Hexakis(imidazole) nickel (II) O,O′-diphenyldithiophosphate [Ni(Im)6](Ph2O2PS2)2
The crystal and molecular structures of [Ni(Im)6](dtp)2 (Im = imidazole, dtp = O,O′-diphenyldithiophosphate) have been determined by X-ray crystallography. It crystallizes in the triclinic system, space group Pī, with cell parameters a = 9.375 (2), b = 12.324(3), c = 13.285(3) Å, α = 107.86(3), β = 102.28(3), γ = 109.24(3), and Z = 1. The crystal structure of the title compound is built up of discrete monomeric molecules of [Ni(Im)6](dtp)2. The nickel (II) ion is hexacoordinated by six imidazole molecules and the coordination environment of Ni (II) is of octahedral geometry. In the solid state, a network of N-H∙∙∙S intermolecular hydrogen bonds connect the Ni(Im)6 moieties and O,O′-diphenyl- dithiophosphate molecules, forming a three-dimensional structure.
Synthesis, crystal structure, spectral properties and catalytic activity of hexakis(imidazole)manganese(II) bisindole-2-carboxylato bisneocuproine bisdimethyl sulfoxide solvates {[MnII(Im)6] · 2(2-IC) · 2(NC) · 2(DMSO)}
Synthesis, X-ray crystal structure and IR spectrum of {[MnII(Im)6] AE 2(2-IC) AE 2(NC) AE 2(DMSO)} (Im = imidazole, 2-HIC = indole-2- carboxylic acid, NC = 2,9-dimethyl-1,10-phenanthroline, DMSO = dimethyl sulfoxide) are reported. The manganese(II) ion has octahedral geometry with a MnN6 core. The crystal structure is completed by two NC, two 2-IC- and two DMSO solvate molecules. The individual cations are linked into chains running parallel to the a axis by four intermolecular hydrogen bonding involving two 2-IC-solvate. Moreover, these chains are connected by p–p stacking interactions which occur between neocuproine molecules related through inversion center. In IR spectroscopy, the compound spectrum is roughly similar to the imidazole one: (i) above 1800 cm1, the bands are broad, but when focussing on some of them a doublet structure can be found; (ii) below 1800 cm1, the bands are sharp and it is then possible to point out the modification of S–O band when this later is involved in bifurcated hydrogen bonding to a second solvate 2-IC-. The compound catalyses the disproportionation of H2O2; moreover an additional quantity of imidazole increases the reaction rate.
An Ultrasensitive Analytical Method Based on Chemiluminescence Sensing Electrochemical Parallel Catalytic Reaction Event
An ultrasensitive electrochemiluminescence (ECL) method on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed for improving ECL analytical characteristics using vanadate(V) as a representative. Vanadate(V) could be electrochemically reduced to generate vanadate(II) which could be chemically oxidized by potassium periodate to regenerate vanadate(V) and give parallel catalytic wave effect. Then, the reduced product of potassium periodate could react with butyl-rhodamine B to emit a sensitive chemiluminescence signal. The chemiluminescence intensity was correlative with vanadate(V) concentration. The investigation on the electrochemical reaction rate constant (k0) confirmed that the speed of electrochemical reaction was faster than that of the subsequent chemiluminescence reaction. The possibility of the combination of electrochemical parallel catalytic reaction with chemiluminescence signal sensing was proved. The similar ECL behaviors could be observed at zirconia nanowires-Nafion modified electrode. Because of the separation and enrichment effect of the modified electrode on vanadate(V), the selectivity and sensitivity was further improved greatly. Based on these findings, a new concept on the combination of electrochemical parallel catalytic reaction and chemiluminesence signal sensing was proposed and an ultrasensitive ECL method for the determination of vanadate(V) was developed at zirconia nanowires-Nafion modified electrode. Under the optimum experimental conditions, the ECL intensity was linear with the concentration of vanadate(V) in the range of 2.0×10−12 mol/L–2.0×10−10 mol/L. The detection limit was 8.0×10−13 mol/L, which was more than 6 orders of magnitude lower than that observed by electrochemical current transduction for electrochemical parallel catalytic reaction at zirconia nanowires-Nafion modified electrode.