Amarta Kumar Pal

A coumarin based Schiff base probe for selective fluorescence detection of Al3 + and its application in live cell imaging

A new coumarin based Schiff base compound, CSB-1 has been synthesized to detect metal ion based on the chelation enhanced fluorescence (CHEF). The cation binding properties of CSB-1 was thoroughly examined in UV-vis and fluorescence spectroscopy. In fluorescence spectroscopy the compound showed high selectivity toward Al3+ ion and the Al3+ can be quantified in mixed aqueous buffer solution (MeOH: 0.01M HEPES Buffer; 9:1; v/v) at pH7.4 as well as in BSA media. The fluorescence intensity of CSB-1 was enhanced by ~24 fold after addition of only five equivalents of Al3+. The fluorescence titration of CSB-1 with Al3+ in mixed aqueous buffer afforded a binding constant, Ka=(1.06±0.2)×104M-1. The colour change from light yellow to colourless and the appearance of blue fluorescence, which can be observed by the naked eye, provides a real-time method for Al3+ sensing. Further the live cell imaging study indicated that the detection of intracellular Al3+ ions are also readily possible in living cell.

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.

Ferrite-supported glutathione: an efficient, green nano-organocatalyst for the synthesis of pyran derivatives

An efficient magnetically retrievable ferrite-supported glutathione nano-organocatalyst has been employed for the synthesis of a library of 2-amino-4H-pyran derivatives in aqueous media via a one-pot multicomponent reaction. The highlight of this protocol lies in its operational simplicity, use of greener solvent, high yield within a very short period of time and reusability of the catalyst. This method provides an alternative greener approach for the synthesis of 2-amino-4H-pyran derivatives.

Nano-Fe3O4@silica sulfuric acid as a reusable and magnetically separable potent solid acid catalyst in Biginelli-type reaction for the one-pot multicomponent synthesis of fused dihydropyrimidine derivatives: A greener NOSE and SFRC approach

ABSTRACT An efficient, highly product selective, eco-friendly, one-pot multicomponent synthesis of dihydropyrimidine derivatives via Biginelli reaction has been described. The reaction was developed by greener nanoparticle-catalyzed organic synthesis enhancement (NOSE) chemistry and solvent free reaction condition (SFRC) approaches, which helped us in making the procedure greener. The reaction went smoothly with a diverse range of aromatic, aliphatic, hetero-aromatic aldehydes, different amine sources, as well as various β-dicarbonyl compounds, showing the flexibility of this methodology. Magnetically separable nano-Fe3O4@SiO2@SO3H, which acts as a potent solid acid catalyst, was characterized by FT-IR, SEM, EDX and TEM, VSM, and TGA analyses. The catalyst was recycled from the reaction mixture easily by an external magnet and reused in five more consecutive runs without much decrease in catalytic activity. Its catalytic efficiency was compared to other nano and bulk solid acid catalyst in order to ascertain the best combination for the conversion. GRAPHICAL ABSTRACT

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.

Nano-FGT: a green and sustainable catalyst for the synthesis of spirooxindoles in aqueous medium

A glutathione grafted nano-organocatalyst (nano-FGT) was used as an efficient catalyst for the synthesis of spirooxindole derivatives. An aqueous medium, easy separation by an external magnet, efficient catalyst reusability, low catalyst loading, and column chromatography free separation of the product makes the present procedure green, sustainable and economically viable. The TON and TOF of the nanocatalyst reached 850 000 and 56 667 min−1 respectively.

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.