Electrochemical studies of a Cu(IICu(III) couple: Cyclic voltammetry and chronoamperometry in a strong alkaline medium and in the presence of periodate anions

Synthesis of a chiral dinuclear Cu(II)-benzothiazolamine complex: evidence of cuprophilic interaction in its structure and exploration of its electrochemical properties and catalytic performance

The synthesis of a chiral dinuclear [Cu(OAc)2(L1)]2 complex (A) and its analogues Cu(OAc)2(L1)2 (B), Cu(OAc)2(L1)PPh3 (C), CuBr(L1)PPh3 (D), and Cu(OAc)2(L2) (E) is described. The X-ray structure of A reveals a cuprophilic interaction (2.65 Å) and shows that L1 behaves as a monodentate ligand. The stereogenic centre in L1 aligns the NH group to form non-covalent interactions with the paddle-wheel acetate groups at variable distances (2.4-2.5 Å and 2.2-2.7 Å). Thermogravimetric analysis confirmed our hypothesis that two equivalents of L1 (B) or a combination of L1 and PPh3 (C) would disrupt the cuprophilic interaction. All complexes, except D, showed irreversible redox waves by cyclic voltammetry. Complexes C and E have lower oxidative peaks (at 10 V s-1) than complex A between +0.40 and +0.60 V. This highlights the influence of ligand(s) on the redox behaviour of Cu(II) complexes. The significance of this electrochemical behaviour was evident in the Chan-Lam (CL) coupling reaction, where 2.5 mol% of A successfully facilitated the formation of a C-N bond. This study showcased the structure, thermal stability, electrochemical properties and catalytic performance of a chiral dinuclear copper(II)-benzothiazolamine complex.

Perylene-Based Coordination Polymers: Synthesis, Fluorescent J-Aggregates, and Electrochemical Properties

The incorporation of electroactive organic building blocks into coordination polymers (CPs) and metal-organic frameworks (MOFs) offers a promising approach for adding electronic functionalities such as redox activity, electrical conductivity, and luminescence to these materials. The incorporation of perylene moieties into CPs is, in particular, of great interest due to its potential to introduce both luminescence and redox properties. Herein, we present an innovative synthesis method for producing a family of highly crystalline and stable coordination polymers based on perylene-3,4,9,10-tetracarboxylate (PTC) and various transition metals (TMs = Co, Ni, and Zn) with an isostructural framework. The crystal structure of the PTC-TM CPs, obtained through powder X-ray diffraction and Rietveld refinement, provides valuable insights into the composition and organization of the building blocks within the CP. The perylene moieties are arranged in a herringbone pattern, with short distances between adjacent ligands, which contributes to the dense and highly organized framework of the material. The photophysical properties of PTC-Zn were thoroughly studied, revealing the presence of J-aggregation-based and monomer-like emission bands. These bands were experimentally identified, and their behavior was further understood through the use of quantum-chemical calculations. Solid-state cyclic voltammetry experiments on PTC-TMs showed that the perylene redox properties are maintained within the CP framework. This study presents a simple and effective approach for synthesizing highly stable and crystalline perylene-based CPs with tunable optical and electrochemical properties in the solid state.

A novel chemiluminescence assay of mitoxantrone based on diperiodatocuprate(III) oxidation

A novel and strong chemiluminescence (CL) of luminol with diperiodatocuprate (K5[Cu(HIO6)2]) was observed in alkaline medium. After the addition of mitoxantrone (MTX) into this system, the CL intensity could be greatly inhibited by MTX. Based on the phenomenon, a sensitive CL method was established for analysis of MTX combining with flow injection technology. Under optimum experimental conditions, the CL intensity was linearly related to the logarithm concentration of MTX from 5.0×10(-9)-1.0×10(-7) g/ml with the detection limit of 1.1×10(-9) g/ml (S/N=3). The relative standard deviation was 1.2% for 5.0×10(-8) g/ml of MTX. The proposed method was successfully applied for determination of MTX in pharmaceutical preparations and biological fluids. The possible CL reaction mechanism was also discussed briefly.

A novel luminol-based chemiluminescence method for the determination of amikacin sulfate in serum by using trivalent copper-periodate complex

A novel chemiluminescence (CL) reaction was based on the oxidizing reaction of luminol by the trivalent copper-periodate complex (K₅[Cu(HIO₆)₂], DPC) in alkaline medium. The CL intensity could be enhanced in the presence of amikacin sulfate (AKS). A new CL method was developed for the determination of AKS by coupling with flow injection (FI) technology. Because of the distinctive oxidative effect of DPC, the luminol-based CL reaction could occur at a low concentration of 10⁻⁷ M. The relative CL intensity was proportional to the concentration of AKS in the range of 4.0×10⁻⁹–4.0×10⁻⁶ g/mL with the detection limit of 1.2×10⁻⁹ g/mL. The relative standard deviation was 2.1% for 8.0×10⁻⁹ g/mL AKS (n=9). The proposed method was successfully applied to the direct determination of AKS at the level of ng/mL in serum samples. The recovery varied from 97.0% to 106.3%. A possible mechanism of the CL reaction was discussed in detail by relating to the CL kinetic characteristics and electrochemical activities of the oxidant DPC.

A flow injection chemiluminescence method for the determination of lincomycin in serum using a diperiodato-cuprate (III)-luminol system

In this paper, the novel trivalent copper-periodate complex {K₅[Cu(HIO₆)₂], DPC} has been applied in a luminol-based chemiluminescence (CL) reaction. Coupled with flow injection (FI) technology, the FI-CL method was proposed for the determination of lincomycin hydrochloride. The CL reaction between luminol and DPC occurred in an alkaline medium. The CL intensity could be greatly enhanced by lincomycin hydrochloride. The relative CL intensity was proportional to the concentration of lincomycin hydrochloride in the range of 1 × 10⁻⁸ to 5 × 10⁻⁶ g mL⁻¹ and the detection limit was at the 3.5 × 10⁻⁹ g mL⁻¹ level. The relative standard deviation at 5 × 10⁻⁸ g mL⁻¹ was 1.7% (n = 9). The sensitive method was successfully applied to the direct determination of lincomycin hydrochloride (ng mL⁻¹) in serum. A possible mechanism of the lumonol-DPC CL reaction was discussed by the study of the CL kinetic characteristics and the spectra of CL reaction. The oxidability of DPC was studied by means of its electrochemical response.

Detection of glucocorticoid residues in pig liver by high-performance liquid chromatography with on-line electrogenerated [Cu(HIO6)2]5−—luminol chemiluminescence detection

A novel method was developed for the simultaneous determination of glucocorticoid residues such as triamcinolone (TR), prednisolone (PR), hydrocortisone (HC), cortisone (CO), methylprednisolone (MP), dexamethasone (DE) and triamcinolone acetonide (TA) by high-performance liquid chromatography (HPLC) coupled with chemiluminescence (CL) detection. The procedure was based on the enhancement effect of glucocorticoids on the chemiluminescence reaction between luminol and the complex of trivalent copper and periodate ([Cu(HIO6)2]5-), which was on-line electrogenerated by constant current electrolysis. The HPLC separation used a Nucleosil RP-C18 column (250 mmx4.6 mm i.d., 5 microm, pore size, 100 A) with a mobile phase consisting of acetonitrile and 1.0 mmol L(-1) ammonium acetate (pH 6.8, 40:60,v/v) at a flow rate of 0.8 mL min(-1). The effects of several parameters on the HPLC resolution and CL emission were studied systematically. Liver samples were hydrolyzed with Helix pomatia juice followed by a solid-phase extraction procedure. Under optimum conditions, the limits of detection (LOD) at a signal-to-noise of 3 ranged from 0.08 to 1.0 ng g(-1) and the limits of quantification (LOQ) at a signal-to-noise of 10 ranged from 0.27 to 3.33 ng g(-1) for seven glucocorticoids. The relative standard deviations (RSD) of intra- and inter-day precision were below 6.8%. The average recoveries for glucocorticoids (spiked at the levels of 5-50 ng g(-1)) in pig liver ranged from 88 to 106%, and the relative standard deviations of the quantitative results were from 2.0 to 6.9%. The proposed method had been successfully applied to the determination of glucocorticoid residues in pig liver.