Diorganotin (IV) Heptacoordinated Complexes Containing Pentadentate [N3O2] Ligands Derived From 5-Substituted-Salicylaldehydes and Diethylenetriamine: Synthesis, Characterization, and Molecular Structure

A stable hybrid catalyst (POM-PPPh3/L/Ni) for the reduction of toxic nitroarene compounds in water

Reduction of nitroarenes to aminoarenes using novel and selective catalysts is an important and desirable approach in green chemistry. In this work, a new heterogeneous nanocatalyst, POM-PPPh3/L/Ni, was designed and prepared via functionalizing a Keggin-type polyoxometalate (H3PMo12O40) with (3-bromopropyl)triphenylphosphonium bromide (BPPPh3Br) through strong electrostatic interactions to prepare [PMo12O40][PPPh3]3 (denoted as POM-PPPh3). The obtained compound was modified via nucleophilic attack of the nitrogen donor of a multidentate Schiff base ligand (L) on its propyl chain to produce [PMo12O40][PPPh3/L]2 (denoted as POM-PPPh3/L), which was finally metallated with nickel cations to achieve [PMo12O40][PPPh3/L/Ni]2 (denoted as POM-PPPh3/L/Ni). After full characterization of the prepared material with various physicochemical methods, its catalytic behavior was investigated in the catalytic nitroarene reduction. The influence of various factors on catalytic conversion and selectivity was considered. The synthesized nanocatalyst showed excellent performance in the reduction of nitroarenes in aqueous media in the presence of NaBH4 as a reducing agent. Mild reaction conditions and a short reaction time (10 min) are the prominent features of this new nanocatalyst. In addition, the catalyst was recovered and reused for up to four cycles of catalytic reduction without any significant loss of conversion.

Synthetic, Spectroscopic, Crystallographic, and Biological Studies of Seven-Coordinated Diorganotin(IV) Complexes Derived from Schiff Bases and Pyridinic Carboxylic Acids

The synthesis and characterisation of diorganotin(iv) monomeric derivatives of pyridine Schiff bases and pyridinic carboxylic acids are reported. All complexes were characterised by mass spectrometry, elemental analyses, IR spectra, and multinuclear NMR analyses. Among them, complexes 5a, 5d, 5e, 5g, and 6a were also confirmed by X-ray crystallography diffraction analyses, which led to establishing that the tin atom is seven-coordinated and has a distorted pentagonal–bipyramidal coordination environment in the solid state and also revealed that both ligands occupy the equatorial positions and the organic substituents the axial positions. The antioxidant activity of the synthetic derivatives towards 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) as well as the thiobarbituric acid reactive substances (TBARS) assay were determined, and were compared with standard antioxidants, showing a dose-dependent activity in both cases. A prominent response was obtained depending on the substituent. The anti-inflammatory activity was also evaluated on a 12-O-tetradecanoylphorbol-13-acetate (TPA) model of induced acute inflammation. The results of the biological tests are discussed in terms of structural characteristics.