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Two newly designed ligands, [4-chloro-2-((((2-pyridyl)ethyl)imino)methyl)phenol] (HL1) and [4-bromo-2-((((2-pyridyl)ethyl)imino)methyl)phenol] (HL2), have been chosen to synthesize two Cu(II) dimeric Schiff base complexes, [CuL1Cl]2 (1) and [CuL2Cl]2 (2), with the aim of studying their catalytic activity towards oxidation of alcohols by using H2O2 as a terminal oxidant and reduction of nitroarenes by using NaBH4 as a reducing agent. The complexes have been characterized using physicochemical techniques and single crystal X-ray diffraction. DFT calculations of both the complexes have also been performed. Complex [CuL1Cl]2 (1) exhibited a higher catalytic efficiency in each reaction and therefore it was selected for building a magnetically separable catalyst by attaching it to surface modified magnetic nanoparticles. Then, our goal was to modify further complex 1 with iron oxide and isonicotinic acid (ISNA), for easy magnetic separation. The new Fe3O4@ISNA@CuL1 catalyst underwent comprehensive characterization, including FT-IR, SEM, TEM, and PXRD analyses, confirming successful copper complex immobilization on the magnetic nanoparticles. These catalysts maintained stability in aqueous and organic media, enabling alcohol oxidation with H2O2 in acetonitrile and nitroarene reduction with sodium borohydride in an aqueous environment. The surface modification with magnetic nanoparticles facilitated easy separation using an external magnet. The novelty of this work lies in its straightforward preparation, minimal time consumption, reduced use of hazardous chemicals, and cost-effectiveness. The catalysts showed recyclability up to five times without significant loss of activity. Furthermore, our synthesized catalysts demonstrated non-toxicity and environmental friendliness. [ABSTRACT FROM AUTHOR]

We have synthesized a novel bronsted acidic surfactant, 3-methyl-1-sulfonic acid imidazolium dioctyl sulfosuccinate [MSIM]+ [DOSS]−. We explored catalytic activity of [MSIM]+ [DOSS]− for regioselective synthesis of novel class of thiazolotriazolones from the reaction of aldehydes/ketones, thiosemicarbazide and ethylbromo acetate in aqueous medium at room temperature. The regio-selectivity was confirmed by DFT and IR frequency calculations. The present methodology offers a feasible approach for swift access to collection of extremely pure products with wide substrate scope having several advantages such as excellent yields, short reaction time, easy work-up procedure for isolation of product and use of surfactant as eco-friendly catalyst, use of water as an universal solvent and novelty in synthesis of surfactant [MSIM]+ [DOSS]− as well as investigation of regioselective synthesis of novel class of thiazolotriazolones. [ABSTRACT FROM AUTHOR]

Poly( N-vinyl-2-pyrrolidone) (PVP) has been used extensively to stabilize the surface of noble metal nanoparticles against aggregation and also to produce anisotropic nanostructures. Naturally, it is very important to understand the effect of such surface stabilization by PVP on the catalytic activity of these nanoparticles. This communication investigates through DFT calculations the electronic properties of PVP stabilized 13-atom Ag cluster for catalytic activation of nitrobenzene (NB). These computations suggest that poly( N-vinyl-2-pyrrolidone) (PVP) interact with silver (Ag) cluster mainly through oxygen atom and acts not only as a stabilizer to prevent the aggregation of Ag clusters but also as an electron donor to activate the Ag clusters for further reaction. Natural Bonding Orbital (NBO) calculations show that catalytic activation of NB by PVP passivated Ag cluster occurs due to interaction of the oxygen of the nitro group with the Ag cluster. Weak back donation of electrons from M(dπ) orbital of Ag to antibonding σ* of one of the NO bond, facilitates the formation of the nitroso intermediate. To understand the extent and the nature of this interaction better, vibrational frequency calculation of nitrobenzene association with Ag13-2PVP cluster is carried out. Red shift in the frequencies is consequence of strong interaction with that of silver cluster present in Ag13-2PVP-NB model. [ABSTRACT FROM AUTHOR]

Abstract: A perfect water square in uudd configuration, built from solvent waters has been isolated from a hybrid metal–organic host [Cu(3-aminomethyl)pyridine oxalateOH2·2H2O]n under self assembly conditions, stabilizing the supramolecular framework through cooperative hydrogen bonding interactions, a rare occurrence among water clusters. The present findings with detailed crystallographic and theoretical studies add to our knowledge regarding the understanding of the contribution of water clusters to the stability and function of biological assemblies as well as the anomalous properties of water. [Copyright &y& Elsevier]

Abstract: The title complex was synthesized under self-assembly conditions using Cu(acetate)2·H2O, 2-amp (=2-aminomethylpyridine) and KSCN, and was characterized by IR, elemental analysis and single crystal structural analysis, and its spectral and RT magnetic properties were investigated. The asymmetric unit consists of a square planar Cu(II) center, with two ligand N atoms and two anionic Ns forming the square plane. In the unit cell, the monomeric complex assembles into 2-D layers through very weak non-bonded interactions between anionic S and Cu2+. Further, the structure was satisfactorily modeled by calculations based on Density Functional Theory (DFT), and the UV–Vis and IR spectra are analyzed in depth with the help of Time Dependent DFT (TDDFT). The results indicate that the absorption maxima are at relatively high energy and are mainly assigned to π→π∗ transitions (in pyridine), with a fair contribution of metal to ligand charge transfer (MLCT) and ligand to ligand charge transfer (LLCT) transitions. All the low lying transitions are categorized as mixed MLCT/LLCT. A very weak but broad band in the higher wavelength region has been detected and identified as a d–d transition band. Also, it has been found that when the ligand ratio is modified, the formation of Cu(2-amp)2(SCN)2 takes place under the same self-assembly conditions, whose structure only has been recently reported. Structural, spectral and theoretical comparisons are presented for both complexes. [Copyright &y& Elsevier]