Mithu Saha

An efficient oxidation of alcohols using a new trinuclear copper complex as a reusable catalyst under solvent free conditions

A new trinuclear copper(II) complex [Cu3(L)(μ2-Cl)2(H2O)6] was synthesized and characterized by various spectroscopic techniques. The trinuclear complex was demonstrated as an efficient catalyst for the selective oxidation of primary, secondary, aliphatic, heteroatomic and conjugated allyl alcohols to the corresponding aldehydes/ketones in good to excellent yields under solvent free conditions using H2O2 as an oxidant. The catalyst is easily synthesizable, easy to handle and reusable up to eight runs.

Graphite oxide: a metal free highly efficient carbocatalyst for the synthesis of 1,5-benzodiazepines under room temperature and solvent free heating conditions

Graphite Oxide (GO), an attractive metal free carbocatalyst, was employed as a green and highly efficient catalytic system for the synthesis of 1,5-benzodiazepines. The reaction was studied at room temperature as well as at 80 °C under solvent free heating conditions. In both cases, GO showed high catalytic activity which is attested by the desired products being produced in good to excellent yields. The present catalytic process eliminates the inconvenience of metal waste disposal, metal contamination in the product and metal toxicity, which are all of significance to the pharmaceutical industry. Furthermore, the present methodology addresses several issues of sustainability and environmental problems such as catalyst reusability (nine consecutive runs), solvent free reaction conditions (SFRC) and high substrate variation. The excellent gram scale applicability also points towards its possible implementation in industrial use.

Pd(0) NPs: a novel and reusable catalyst for the synthesis of bis(heterocyclyl)methanes in water

A ligand free, Pd-nanoparticle catalyzed synthesis of bis(heterocyclyl)methane derivatives is described herein. The advantages of this method lie in its simplicity, cost effectiveness and environmentally friendliness. The process is very green, as water is exploited as the reaction medium.

Nano-ferrite supported glutathione as a reusable nano-organocatalyst for the synthesis of phthalazine-trione and dione derivatives under solvent-free conditions

Nano-organocatalyzed one-pot four-component reactions for the synthesis of phthalazine-trione/dione derivatives have been devised for the first time from easily accessible starting materials under solvent-free conditions. This methodology showed very good substrate scope and high degree of tolerance for a variety of aldehydes (including aliphatic and heteroaromatic aldehydes) and active methylene compounds. Moreover, the catalyst can be easily separated from the reaction mixture because of its highly paramagnetic nature, by using an external magnet, and can be reused in five more consecutive runs without much decrease in catalytic activities. Other significant advantages of this method are shorter reaction time, good yield, simple work-up procedure, easy catalyst handling etc.

Solvent free, Ni-nanoparticle catalyzed greener synthesis and photophysical studies of novel 2H-indazolo[2,1-b] phthalazine-trione derivatives

A nickel nanoparticle (NPs) catalyzed one-pot three component reaction of phthalhydrazide, dimedone and aryl aldehydes under solvent free conditions has been reported. The present approach offers the advantages of simple methodology, clean and mild reaction conditions, short reaction time, low environmental impact, high yield, and excellent purity. The synthesized compounds (2H-indazolo[2,1-b] phthalazine-trione) are found to be suitable candidates for efficient fluorogenic assays to monitor bio-chemical environments.

An efficient facile and one-pot synthesis of benzodiazepines and chemoselective 1,2-disubstituted benzimidazoles using a magnetically retrievable Fe3O4 nanocatalyst under solvent free conditions

Benzodiazepine and chemoselective 1,2-disubstituted benzimidazole derivatives were synthesized by the condensation reaction of o-phenylenediamine with ketones and aryl aldehydes using Fe3O4 nanoparticles as a recyclable catalyst under solvent free conditions. This synthetic approach eliminates the use of toxic organic solvents with the added benefit of easy separation and reusability of the catalyst without compromising the yield or purity which makes the procedure green.

Regioselective synthesis of functionalized [1,6]-naphthyridines by KF/basic alumina as a recyclable catalyst and a brief study of their photophysical properties

ABSTRACT An efficient, one-pot, solvent-free, regioselective synthesis of functionalized [1,6]-naphthyridines was explored by a heterogeneous catalyst via a three-component multicomponent reaction (MCR). KF/basic alumina–catalyzed double heteroannulation of aryl alkyl ketones, malononitrile, and alkyl amines generates the compounds with high appendage diversity combinatorially via Knoevenagel condensation followed by Michael addition and cyclization pathway. Short reaction time, high yield, simple reaction technique, and recoverability and reusability of the catalyst without compromising the yield and purity of the compounds are the salient features of this methodology. Additionally, these compounds exhibit promising photophysical properties. GRAPHICAL ABSTRACT

Regioselective nitration of aromatic compounds in an aqueous sodium dodecylsulfate and nitric acid medium

An aqueous solution of sodium dodecylsulfate in the presence of dilute nitric acid at room temperature works as a mild medium for the nitration of aromatic compounds with high regioselectivity.

Magnetically Recyclable Nano-FDP: A Novel, Efficient Nano-Organocatalyst for the One-Pot Multi-Component Synthesis of Pyran Derivatives in Water Under Ultrasound Irradiation

Highly stable, super-paramagnetic nanoparticle supported l-proline catalyst (nano-FDP) which shows extra-ordinary catalytic activity was synthesized for the first time from economical and easily available starting materials. Characterization of the synthesized catalyst was done by FT-IR, EDX, SEM and TEM analysis. Application of this for synthesis of pyran derivatives under ultrasonication at room temperature showed excellent results. Use of water as a solvent which is nature’s own reaction medium, shorter reaction time, high yield of the desired product, recovery of the catalyst by external magnetic field, and its reusability in further runsare the added advantages of this methodology.Graphical Abstract

Novel Triindolo-Truxene Derivatives: Design, Synthesis, and Fine-Tuning of Electronic Properties and Molecular Assembly through Molecular Engineering

Triindolo-truxene, a C3 -symmetric molecule with a large π-conjugated plane, has six methylene carbon atoms and three aromatic carbon atoms that can be facilely functionalized. Herein, butyl, carbonyl, cyano, and/or malononitrile groups were introduced at six methylene carbon atoms (6-, 14-, 22- or 8-, 16-, 24-positions) and/or three aromatic carbon atoms (2-, 10-, and 18-positions) of triindolo-truxene to produce eight derivatives. Their photophysical properties, electrochemical properties, and molecular assembly can be effectively modulated by substituents and substitution patterns. Incorporation of electron-deficient groups led to redshifts in both the absorption and emission of these derivatives and also lowered their HOMO and LUMO levels. Different substitution patterns resulted in the different intramolecular donor-acceptor interactions. Electron-deficient substituents at the methylene carbon atoms in the 6-, 14-, and 22-positions led to intramolecular charge transfer from the fluorene arms to the truxene core, whereas the corresponding substitutions at the methylene carbon atoms in the 8-, 16-, and 24-positions resulted in intramolecular charge transfer from the truxene core to the fluorene arms. The molecular packing in single crystals and molecular aggregation in solution are also influenced by the substituents and substitution patterns. This work provides a straightforward strategy to alter the properties of triindolo-truxene.