National Chemical Laboratory

About: National Chemical Laboratory is a facility organization based out in Pune, Maharashtra, India. It is known for research contribution in the topics: Catalysis & Nanoparticle. The organization has 8891 authors who have published 14837 publications receiving 387600 citations.

Efficiency and recycling capability of montmorillonite supported Fe–Ni bimetallic nanocomposites towards hexavalent chromium remediation

Abstract: The remediation of Cr(VI) from simulated water streams is investigated using Fe–Ni bimetallic nanoparticles (Fe–Ni NPs) and their nanocomposites prepared with montmorillonite (MMT) clay. These nanocomposites are characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyses. XRD analysis revealed proper dispersion as well as intercalation of Fe–Ni NPs in the clay matrix. TEM of nanocomposites showed the presence of spherical particles having a size of 20–40 nm. Batch experiments with a 25 mg L−1 Cr(VI) solution and 2 g L−1 Fe–Ni NPs exhibited complete reduction of Cr(VI) within 10 min that follows first order reaction kinetics. Amongst 25%, 50%, 75% in situ and loaded nanocomposites, 75% compositions possess better activity with enhanced reduction capacity below pH 4 due to generation of reactive H species. XPS analysis of nanocomposites after Cr(VI) treatment suggested that reduction process occurs through Cr(III) formation followed by its subsequent reduction to Cr(0). Their potentiality towards reusage is established from the recycling experiments that revealed the order of efficiency as 75% in situ > Fe–Ni NPs > 75% loaded nanocomposites.

Phenothiazine and carbazole substituted pyrene based electroluminescent organic semiconductors for OLED devices

Abstract: Due to their easy availability, low cost and opportunities for exploiting reactions of bromo substituents, 1,3,6,8-tetrabromopyrene has attracted major attention in the organic electronics community for designing and constructing novel classes of pyrene based organic semiconducting functional materials. In the present work, 1,3,6,8-tetrabromo pyrene was transformed into the corresponding tetrasubstituted carbazole and phenothiazine derivatives using the classical Suzuki coupling reaction. These newly synthesized materials with a carbazole substituent (PY-CA) and a phenothiazine substituent (PY-PH) were characterised thoroughly and were successfully used as an active light-emitting layer in organic light emitting diodes which resulted in blue and green emission with promising device performance. PY-CA exhibited the maximum brightness at around 2500 cd m−2 and the power efficiency of 1.5 lm W−1 while that of PY-PH exhibited 2116 cd m−2 and 0.45 lm W−1 respectively.

Enantioselective N-Heterocyclic Carbene-Catalyzed Annulations of 2-Bromoenals with 1,3-Dicarbonyl Compounds and Enamines via Chiral α,β-Unsaturated Acylazoliums

Abstract: The N-heterocyclic carbene (NHC)-cata- lyzed generation of chiral a,b-unsaturated acylazoli- ums from 2-bromoenals followed by their intercep- tion with 1,3-dicarbonyl compounds or enamines, the formal (3+3) annulation reaction, is reported. The re- action results in the enantioselective synthesis of syn- thetically and medicinally important dihydropyran- A and dihydropyridinones, and tolerates a wide range of functional groups. It is noteworthy that the reaction takes place under mild reaction conditions utilizing relatively low catalyst loadings. In addition, based on DFT calculations, a mechanistic scenario involving the attack of the nucleophile from below the plane of the a,b-unsaturated acylazoliums, and the mode of enantioinduction is presented.

Hydrolysis of vegetable oils and fats to fatty acids over solid acid catalysts

Abstract: Solid Fe-Zn double-metal cyanide (DMC) complexes exhibit high catalytic activity for hydrolysis of edible and non-edible vegetable oils and animal fat. In a batch reaction, complete conversion of vegetable oil triglycerides to fatty acids with selectivity greater than 73 wt% was obtained at temperatures as low as 463 K, autogenous pressure and with 5 wt% of catalyst. Catalytic activity of DMC was superior to Amberlyst™70, SAPO-11, H-β, HY, MoOx/Al2O3 and sulfated zirconia. Rates of hydrolysis were greatly enhanced when solvents (tetrahydrofuran or N,N-dimethylformamide), phase transfer agents (tetrapropyl ammonium bromide) and products (a mixture of mono-/diglycerides and fatty acids) or fatty acid was added to the feed. Surface hydrophobicity which enables high wettability and activation of glycerides on active, acidic sites of reusable DMC is attributed to be the major cause for its superior catalytic activity.