Photo-induced reduction of CO2 using a magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4 catalyst under visible light irradiation.

An efficient photo-induced reduction of CO2 using magnetically separable Ru-CoPc@TiO2@SiO2@Fe3O4 as a heterogeneous catalyst in which CoPc and Ru(bpy)2phene complexes were attached to a solid support via covalent attachment under visible light is described. The as-synthesized catalyst was characterized by a series of techniques including FTIR, UV-Vis, XRD, SEM, TEM, etc. and subsequently tested for the photocatalytic reduction of carbon dioxide using triethylamine as a sacrificial donor and water as a reaction medium. The developed photocatalyst exhibited a significantly higher catalytic activity to give a methanol yield of 2570.78 µmol per g cat after 48 h.

Cobalt phthalocyanine immobilized on graphene oxide: an efficient visible-active catalyst for the photoreduction of carbon dioxide.

New graphene oxide (GO)-tethered-Co(II) phthalocyanine complex [CoPc-GO] was synthesized by a stepwise procedure and demonstrated to be an efficient, cost-effective and recyclable photocatalyst for the reduction of carbon dioxide to produce methanol as the main product. The developed GO-immobilized CoPc was characterized by X-ray diffraction (XRD), FTIR, XPS, Raman, diffusion reflection UV/Vis spectroscopy, inductively coupled plasma atomic emission spectroscopy (ICP-AES), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). FTIR, XPS, Raman, UV/Vis and ICP-AES along with elemental analysis data showed that Co(II) -Pc complex was successfully grafted on GO. The prepared catalyst was used for the photocatalytic reduction of carbon dioxide by using water as a solvent and triethylamine as the sacrificial donor. Methanol was obtained as the major reaction product along with the formation of minor amount of CO (0.82 %). It was found that GO-grafted CoPc exhibited higher photocatalytic activity than homogeneous CoPc, as well as GO, and showed good recoverability without significant leaching during the reaction. Quantitative determination of methanol was done by GC flame-ionization detector (FID), and verification of product was done by NMR spectroscopy. The yield of methanol after 48 h of reaction by using GO-CoPc catalyst in the presence of sacrificial donor triethylamine was found to be 3781.8881 µmol g(-1) cat., and the conversion rate was found to be 78.7893 µmol g(-1) cat. h(-1). After the photoreduction experiment, the catalyst was easily recovered by filtration and reused for the subsequent recycling experiment without significant change in the catalytic efficiency.

PEG-embedded KBr(3): A recyclable catalyst for multicomponent coupling reaction for the efficient synthesis of functionalized piperidines.

PEG-embedded potassium tribromide ([K(+)PEG]Br(3) (-)) was found to be an efficient and recyclable catalyst for the synthesis of functionalized piperidines in high yields in a one step, three component coupling between aldehyde, amine and ß-keto ester. At the end of the reaction the [K(+)PEG]Br(3) (-) was readily regenerated from the reaction mixture by treating the residue containing [K(+)PEG]Br(-) with molecular bromine.

Graphene oxide: an efficient and reusable carbocatalyst for aza-Michael addition of amines to activated alkenes.

Graphene oxide was found to be a highly efficient, reusable and cost-effective organocatalyst for the aza-Michael addition of amines to activated alkenes to furnish corresponding ß-amino compounds in excellent yields.

Thiourea dioxide promoted efficient organocatalytic one-pot synthesis of a library of novel heterocyclic compounds.

The utility of thiourea dioxide as an efficient organocatalyst for the library synthesis of novel heterocyclic compounds via one-pot multicomponent coupling reactions is disclosed. Thiourea dioxide is an inexpensive and readily accessible catalyst, resulting in better product yields as compared to the corresponding thiourea as catalyst. Thiourea dioxide is found to be insoluble in various organic solvents and therefore at the end of the reaction products can be separated by extraction with diethyl ether and the recovered catalyst can be used several times with consistent catalytic activity.

Polyethylene glycol clicked Co(II) Schiff base and its catalytic activity for the oxidative dehydrogenation of secondary amines.

Copper catalyzed [3+2] cycloaddition "click method" provided an efficient and high yielding immobilization of cobalt(II) Schiff base to the azido-functionalized MeOPEG(5000); whereas the direct reaction between MeOPEG(5000) and Co(II) Schiff base did not produce any immobilization. The prepared catalyst was tested for the oxidative dehydrogenation of various secondary amines using TBHP as oxidant and could be easily recovered by precipitation with diethyl ether at the end of the reaction.

An efficient biomaterial supported bifunctional organocatalyst (ES-SO3- C5H5NH+) for the synthesis of ß-amino carbonyls.

A biomaterial supported organocatalyst, readily synthesized by the reaction of chemically modified sulfonic group containing expanded corn starch with pyridine exhibited excellent catalytic activity for the synthesis of ß-amino carbonyls in excellent yields via aza-Michael addition of amines to electron deficient alkenes. A remarkable enhancement in the reaction rates was observed with the prepared bifunctional organocatalyst in comparison to the either starch grafted sulfonic acid or the corresponding homogeneous pyridinium p-toluenesulfonate.

Cyclotriphosphazene grafted silica: a novel support for immobilizing the oxo-vanadium Schiff base moieties for hydroxylation of benzene.

The first report on the use of chlorotriphosphazenyl anchored mesoporous silica as a novel support for the immobilization of oxo-vanadium Schiff base moieties is described. The resulting heterogeneous material showed better catalytic activity than homogeneous as well as silica immobilized oxo-vanadium Schiff base for the hydroxylation of benzene with hydrogen peroxide.

Click on silica: systematic immobilization of Co(II) Schiff bases to the mesoporous silica via click reaction and their catalytic activity for aerobic oxidation of alcohols.

The systematic immobilization of cobalt(II) Schiff base complexes on SBA-15 mesoporous silica via copper catalyzed [3 + 2] azide-alkyne cycloaddition (CuAAC) "click reaction" involving either step-wise synthesis of silica-bound Schiff base ligand followed by its subsequent complexation with cobalt ions, or by the direct immobilization of preformed Co(II) Schiff base complex to the silica support is described. The catalytic activity of the prepared complexes was studied for the oxidation of alcohols to carbonyl compounds using molecular oxygen as oxidant. The immobilized complexes were recycled for several runs without loss in catalytic activity and no leaching was observed during this course.

An efficient aerobic oxidative cyanation of tertiary amines with sodium cyanide using vanadium based systems as catalysts.

The first report on the use of vanadium-based catalysts for oxidative cyanation of tertiary amines with molecular oxygen in the presence of sodium cyanide and acetic acid to afford the corresponding alpha-aminonitriles in good to excellent yields is described.

Ruthenium catalyzed oxidation of tertiary nitrogen compounds with molecular oxygen: an easy access to N-oxides under mild conditions.

A variety of tertiary nitrogen compounds have been efficiently oxidized to their corresponding N-oxides in excellent yields with molecular oxygen as a sole oxidant and ruthenium trichloride as catalyst.