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A novel platform of a polydiacetylene combined with rhodamine B (PDA-Rho) colorimetric chemosensor array was prepared from a diacetylene monomer and rhodamine B derivative. Rhodamine B derivative as the ion-recognition element was embedded in the polydiacetylene matrix. To fabricate chemosensor, diacetylene monomer connected rhodamine B derivatives (DA-Rho) was coated onto a filter paper surface via drop-casting technique and transformed to polydiacetylene by polymerisation through ultraviolet (UV) irradiation. From the result, PDA-Rhoen exhibited high sensitivity and selectivity for Au3+ and could be monitored directly by naked eyes providing a fast, portable and easy-to-use as a molecular device in the real system. The DFT calculation results showed a stable complex between PDA-Rho and Au3+. We believe that, this method offers a sensitive and accurate process for Au3+ ion detection in real environmental and biological applications. [ABSTRACT FROM AUTHOR]

Simple and green conditions for copper-catalysed ATRA reactions in water have been developed. Firstly, [Cu(ADPA)(H2O)(ClO4)2] (1b, ADPA = 9-[(2,2′-dipicolylamino)methyl]anthracene) was demonstrated to be capable of selectively catalysing the ATRA of CCl4 to styrene using L-ascorbic acid (AsH2) as a reducing agent in organic solvent mixtures under ambient atmosphere. Mechanistic investigation suggested that our ATRA reaction proceeded via a single-electron transfer (SET) mechanism through an inner-sphere complex, which is consistent with the widely accepted mechanism for copper-catalysed ATRA. To perform the reaction in water as a sole solvent, a biocompatible surfactant (2 wt% Tween 20 or Tween 80) was added to improve solubility and increase the local concentration of organic reagents and the copper catalyst. Without the need for a complicated oxygen-free set-up, the ATRA reaction catalysed by this simple aqueous-dispersed system can be performed at a mild temperature (60 °C) and a relatively short reaction time (6 h) using 1 mol% of the catalyst. Furthermore, this facile protocol is also applicable for other alkene substrates demonstrated in this work, resulting in satisfactory to excellent substrate conversion and product yields. [ABSTRACT FROM AUTHOR]

In this work, new hybrid catalysts based on molecularly dispersed nickel complexes on N-doped graphene were developed for electrochemical CO2 reduction (ECR). Nickel(II) complexes (1-Ni, 2-Ni), and a new crystal structure ([2-Ni]Me), featuring N4-Schiff base macrocycles, were synthesized and investigated for their potential in ECR. Cyclic voltammetry (CV) in NBu4PF6/CH3CN solution demonstrated that the nickel complexes bearing N–H groups (1-Ni and 2-Ni) showed a substantial current enhancement in the presence of CO2, while the absence of N–H groups ([2-Ni]Me) resulted in an almost unchanged voltammogram. This indicated the necessity of the N–H functionality towards ECR in aprotic media. All three nickel complexes were successfully immobilized on nitrogen-doped graphene (NG) via non-covalent interactions. All three Ni@NG catalysts exhibited satisfactory CO2-to-CO reduction in aqueous NaHCO3 solution with the faradaic efficiency (FE) of 60–80% at the overpotential of 0.56 V vs. RHE. The ECR activity of [2-Ni]Me@NG also suggested that the N–H moiety from the ligand is less important in the heterogeneous aqueous system owing to viable hydrogen-bond formation and proton donors from water and bicarbonate ions. This finding could pave the way for understanding the effects of modifying the ligand framework at the N–H position toward fine tuning the reactivity of hybrid catalysts through molecular-level modulation. [ABSTRACT FROM AUTHOR]

Copper‐catalyzed cycloalkane oxidation using H2O2 as an oxidant was investigated under mild conditions. The copper catalysts studied in this work ranged from commercially‐available copper(II) salts to copper(II) complexes containing polypyridyl ligands. Various factors that affected catalytic activity of copper catalysts were elucidated. It was found that geometry of the copper complex in solution and coordinated anions played important roles in catalytic activity. The copper(II) complex generated in‐situ by mixing Cu(OAc)2 and TMPA ligand (TMPA=tris(2‐pyridylmethyl)amine) adopted trigonal bipyramidal geometry and was competent to catalyze cyclohexane oxidation with higher yields, compared to those of other Cu2+ species used in this work. The optimal catalytic condition was achieved using 1.0 % mol of Cu(OAc)2/TMPA and 10 equivalents of H2O2 with respect to cyclohexane in CH3CN at 33–35 °C for 3 hours, resulting in the total product yield of 44 %. Moreover, since cyclohexyl hydroperoxide was detected as a major product, the Fenton‐like mechanism via one electron process was proposed as a plausible mechanism in this cycloalkane oxidation. In addition, our catalytic system was further demonstrated to be applicable for oxidation of various cycloalkane substrates with moderate yields and relatively short time. [ABSTRACT FROM AUTHOR]