Unlocking catalytic potential: a rhodium(II)-based coordination polymer for efficient carbene transfer reactions with donor/acceptor diazoalkanes.

Herein, we report the use of a molecular-defined rhodium(II) coordination polymer (Rh-CP) as a heterogeneous, recyclable catalyst in carbene transfer reactions. We showcase the application of this heterogeneous catalyst in a range of carbene transfer reactions and conclude with the functionalization of natural products and drug molecules.

Efficient Electrochemical Lead Detection by a Histidine-Grafted Metal-Organic Framework MOF-808 Electrode Material.

As the excessive presence of heavy metals in the environment significantly affects human health, it becomes necessary to develop efficient, selective, and sensitive methods for their detection. In this study, a novel electrochemical sensor for the detection of Pb2+ ions is described. The proposed sensor is based on a glassy carbon electrode (GCE) modified by a thin film of histidine-grafted metal-organic framework (MOF-808-His). The MOF-808 was obtained solvothermally, and then postsynthetically modified by substituting the coordinated acetate with histidinate. By electrochemistry, the MOF-808-His-modified GCE demonstrated high charge selectivity, while electrochemical impedance spectroscopy (EIS) and kinetic studies gave a lower charge transfer resistance (4196 Ω) and a better standard heterogeneous electron transfer rate constant (1.80 × 10-5 cm s-1) on MOF-808-modified GCE. These results indicated a swift and direct electron transfer rate from [Fe(CN)6]3-/4- to the electrode surface. Using square wave anodic stripping voltammetry (SWASV), the rapid and highly sensitive determination of Pb2+ was achieved on MOF-808-His-modified GCE. By optimizing the accumulation-detection parameters including pH of the detection medium, deposition time and potential, and concentration, a remarkable limit of detection (LoD, based on a signal-to-noise ratio of 3) of (1.12 × 10-10 ± 0.10 × 10-10) mol L-1 was obtained, with a sensitivity of (9.6 ± 0.1) µA L µmol-1. After interference and stability studies, the MOF-808-His-modified GCE was applied to the detection of Pb2+ in a tap water sample with a concentration of 10 µmol L-1 Pb2+.

The efficient removal of ibuprofen, caffeine, and bisphenol A using engineered egusi seed shells biochar: adsorption kinetics, equilibrium, thermodynamics, and mechanism.

Contaminants of emerging concern (CECs), also known as micropollutants, have been recognized in recent years as substantial water pollutants because of the potential threats they pose to the environment and human health. This study was aimed at preparing biochar (BC) based on egusi seed shells (ESS) with well-developed porosity and excellent adsorption capacity towards CECs including ibuprofen (IBP), caffeine (CAF), and bisphenol A (BPA). BC samples were prepared by pyrolysis at different temperatures (400 to 800 °C) and were characterized using nitrogen sorption, FTIR, powder X-ray diffraction (PXRD), SEM/EDS, elemental analysis, and thermal analysis. The nitrogen sorption and SEM results showed that the textural properties were more prominent as the pyrolysis temperature increased. The BC sample obtained at 800 °C which exhibited the largest specific surface area (688 m2/g) and the highest pore volume (0.320 cm3/g) was selected for the adsorption study of CECs. The kinetic study shows that the adsorption equilibrium of CAF and BPA was faster than that of IBP. The pseudo-first- and pseudo-second-order kinetic models best fitted the adsorption data. The Langmuir maximum monolayer adsorption capacities of biochar were found to be ~ 180, 121, and 73 mg/g respectively for IBP, CAF, and BPA. The thermodynamic study shows that the adsorption process was spontaneous and endothermic for the three CECs. The results of the adsorption and the analysis of BC after adsorption showed that hydrogen bonding, van der Waals, π-π, n-π interactions, and pore filling were involved in the adsorption mechanism. The prepared biochar BC from ESS displayed a large surface area and good morphology and significantly promotes adsorption of CECs and good efficiency on synthetic effluent. Finally, it offers a low-cost and cleaner production method.

Tunable Aryl Alkyl Ionic Liquid Supported Synthesis of Platinum Nanoparticles and Their Catalytic Activity in the Hydrogen Evolution Reaction and in Hydrosilylation.

Tunable aryl alkyl ionic liquids (TAAILs) are ionic liquids (ILs) with a 1-aryl-3-alkylimidazolium cation having differently substituted aryl groups. Herein, nine TAAILs with the bis(trifluoromethylsulfonyl)imide anion are utilized in combination with and without ethylene glycol (EG) as reaction media for the rapid microwave synthesis of platinum nanoparticles (Pt-NPs). TAAILs allow the synthesis of small NPs and are efficient solvents for microwave absorption. Transmission electron microscopy (TEM) shows that small primary NPs with sizes of 2 nm to 5 nm are obtained in TAAILs and EG/TAAIL mixtures. The Pt-NPs feature excellent activity as electrocatalysts in the hydrogen evolution reaction (HER) under acidic conditions, with an overpotential at a current density of 10 mA cm-2 as low as 32 mV vs the reversible hydrogen electrode (RHE), which is significantly lower than the standard Pt/C 20% with 42 mV. Pt-NPs obtained in TAAILs also achieved quantitative conversion in the hydrosilylation reaction of phenylacetylene with triethylsilane after just 5 min at 200 °C.

The Viability of C5-Protonated- and C4,C5-Ditopic Carbanionic Abnormal NHCs: A New Dimension in NHC Chemistry.

The first C5-protonated abnormal N-heterocyclic carbene (aNHC), PhC{N(2,6-iPr2 C6 H3 )}2 CHC: (4) is readily accessible by C4-deprotonation of [ArC{N(2,6-iPr2 C6 H3 )}2 CHCH]X (3 a-X) (Ar=Ph, X=Br or I) with a base. The aNHC 4 is stable at 298 K in [D8 ]THF solution and has been spectroscopically characterized. The facile availability of 4 enables the synthesis of a series of main-group compounds as well as transition-metal complexes featuring a new phosphorus-aNHC hybrid ligand. Double deprotonation of [ArC{N(2,6-iPr2 C6 H3 )}2 CHCH]X (Ar=Ph, 3 a-X (X=Br or I); 4-Tol, 3 b-Br; 4-DMP, 3 c-Br; Tol=MeC6 H4 , DMP=Me2 NC6 H4 ) with nBuLi yields the C4,C5-ditopic carbanionic aNHCs, [ArC{N(2,6-iPr2 C6 H3 )}2 (C:)2 ]Li(THF)n (Ar=Ph, 13 a; 4-Tol, 13 b; 4-DMP, 13 c), which on treatment with Ph2 PCl affords cationic vicinal bisphosphine derivatives [ArC{N(2,6-iPr2 C6 H3 )}2 {C(PPh2 }2 ]X (Ar=Ph, 14 a-X, X=Br or I; 4-Tol, 14 b-Br; 4-DMP, 14 c-Br).