Debkumar Nandi

Microwave assisted azide–alkyne cycloaddition reaction using polymer supported Cu(I) as a catalytic species: a solventless approach

A polymer supported copper(I) composite has been synthesized using a one-step chemical synthesis route under ambient conditions. The resultant material serves as an effective catalyst for a 1,3-dipolar cycloaddition reaction between terminal alkynes and azides to synthesize 1,2,3-triazoles with excellent yields using a microwave irradiation technique in the absence of any solvent. The composite has also been found to be an effective catalyst for the multicomponent synthesis of 1,2,3-triazoles from organic halides, sodium azide and terminal alkynes under the identical conditions as mentioned above.

Suzuki coupling reaction in the presence of polymer immobilized palladium nanoparticles: a heterogeneous catalytic pathway

An in situ method for the fabrication of a metal–polymer composite architecture using the precursors of 1,2-diaminobenzene (DAB) and potassium tetrachloropalladate (K2PdCl4) has been reported in this manuscript where palladium nanoparticles were stabilized by the poly-(1,2-diaminobenzene), pDAB, matrix. During the reaction, DAB was oxidized, which produced pDAB, on the other hand the reduction of palladium salt formed palladium nanoparticles which were found to be uniformly dispersed throughout the macromolecule matrix. The composite material was characterized by means of different techniques, such as UV-visible and infrared spectroscopy, which has contributed the information regarding the chemical structure of the polymer, whereas electron microscopy images yielded the information regarding the size and distribution of the metal particles in the polymer matrix. The composite material was successfully employed as a catalyst for the coupling of phenylboronic acid with aryl halides (Suzuki reaction) in the presence of an inorganic base under phosphine-free condition.

Gold nanoparticle within the polymer chain, a multi-functional composite material, for the electrochemical detection of dopamine and the hydrogen atom-mediated reduction of Rhodamine-B, a mechanistic approach

Polymer-stabilized gold nanoparticles have been reported using an in situ chemical synthesis route where the gold nanoparticles were uniformly dispersed throughout the macromolecular chain and formed a uniform metal–polymer composite material. The surface properties of the composite material were characterized using X-ray diffraction and X-ray photoelectron spectroscopy techniques. The electron transfer resistance (ETR) value of the resultant material was measured using electrochemical impedance spectroscopy technique. By incorporating the gold nanoparticles in the polymer matrix, the ETR value of the composite material was decreased as compared with the pure polymer and showed the efficient catalytic performance for the electrochemical recognition of dopamine. The gold–polymer composite performed as a highly efficient material for the reduction of Rhodamine-B, which suggests that the reduction process was driven by the hydrogen atom transfer mechanism and catalyzed by the gold nanoparticles.

Carbon nitride supported copper nanoparticles: light-induced electronic effect of the support for triazole synthesis

The composite framework of graphitic carbon nitride (gCN) supported copper nanoparticle can act as a high-performance photoreactor for the synthesis of 1,2,3-triazole derivatives under light irradiation in the absence of alkaline condition. The photoactivity of gCN originates from an electron transition from the valence band to the conduction band, in the presence of photon energy, and the hot electron acts as a scavenger of the terminal proton of the alkyne molecule to facilitate the formation of copper acetanilide complex. In this study, we have performed the experiment under a different photonic environment, including dark condition, and in the presence and absence of base. A comparative study was also executed using Cu-TiO2 system, as a reference material, in the support of our proposed mechanism. The recycling performance and the photocorrosion effect of the catalyst have also been reported in this study.

Catalytic performance of the in situ synthesized palladium–polymer nanocomposite

Polymer encapsulated metallic palladium nanoparticles have been synthesized via the oxidative polymerization route using a di-amino naphthalene monomer and a palladium based metal salt. The resultant composite material was characterized by means of optical and microscopic techniques, which offered the information about the chemical structure of the polymer and also the distribution of the metal particles in the composite material. The palladium nanoparticles were homogeneously dispersed throughout the polymer which produced a uniform metal–polymer composite material. The composite material was successfully used for the hydrogenation reaction of the 4-nitrophenolate ion with the evidence of a proton coupled electron transfer (PCET) reaction mechanism. The palladium–polymer composite material was also used as an iodide sensor for the detection of the iodide ion in the presence of other interfering anionic species.

A carbon nitride supported copper nanoparticle composite: a heterogeneous catalyst for the N-arylation of hetero-aromatic compounds

A graphitic carbon nitride supported copper nanoparticle composite (Cu–gCN) has been found to be an active catalyst for the N-arylation of hetero-aromatic systems (pyrrole, pyrazole, and substituted indole) and benzamide molecules, with high product selectivity and good to excellent yields, using substituted aryl bromide as a coupling partner. The intercalated structure and the amine functional group of the carbon nitride prevent the aggregation of the catalytically active copper species during the reaction, and the recyclability study shows the stable performance of the catalyst without a significant loss of catalytic activity.

Light effect on Click reaction: Role of photonic quantum dot catalyst

Due to the light excitation, the valence band electron of the copper (I) sulfide quantum dot transfer to the conduction band and act as a scavenger of the terminal proton of the alkyne in the presence of organic azide with the formation of 1,4-disubstituted 1,2,3-triazoles, where the copper(I) species of Cu2S act as a catalyst for the reaction. The above cycloaddition reaction between alkyne and azide is commonly known as the Click reaction. In this study, experiments were carried out under the exposure of ultra-violate and daylight and also dark environment. According to the original recommendation for the Click reaction, the role of the base was also considered for this experiment. We found that the effect of conduction band electron is more efficient than the recommended conventional base mediated reaction procedure.

A palladium nanoparticle-catalyzed aryl–amine coupling reaction: high performance of aryl and pyridyl chlorides as the coupling partner

Carbon nitride (CN)-supported nanosized palladium particles, Pd–CN, have been found to be an active catalyst system for the amination of aryl and pyridyl chloride moieties in the presence of dialkyl amine under mild reaction conditions. The recyclability study of the reaction shows the stable performance of the catalyst without a significant loss of catalytic activity for a couple of cycles.