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 & Enantioselective synthesis. The organization has 8891 authors who have published 14837 publications receiving 387600 citations.

Efficient Exciton to Dopant Energy Transfer in Mn2+-Doped (C4H9NH3)2PbBr4 Two-Dimensional (2D) Layered Perovskites

Abstract: Three-dimensional ABX3 perovskite material has attracted immense interest and applications in optoelectronic devices, because of their enabling properties. Recently, Mn2+ doping directly into APbCl3-type three-dimensional (3D) nanocrystals, manifesting host-to-dopant energy transfer, have been reported for LED display applications. Strongly bound excitons in the doped system can enhance the dopant-carrier exchange interactions, leading to efficient energy transfer. Here, we report the simple and scalable synthesis of Mn2+-doped (C4H9NH3)2PbBr4 two-dimensional (2D) layered perovskites. The Mn2+-doped 2D perovskite shows enhanced energy transfer efficiency from the strongly bound excitons of the host material to the d electrons of Mn2+ ions, resulting in intense orange-yellow emission, which is due to spin-forbidden internal transition (4T1 → 6A1) with the highest quantum yield (Mn2+) of 37%. Because of this high quantum yield, stability in ambient atmosphere, and simplicity and scalability of the synthetic...

Selective Catalytic Transesterification, Transthiolesterification, and Protection of Carbonyl Compounds over Natural Kaolinitic Clay

Abstract: Transesterification and transthiolesterification of β-keto esters with variety of alcohols and thiols and selective protection of carbonyl functions with various protecting groups catalyzed by natural kaolinitic clay are described. The clay has been found to be an efficient catalyst in transesterifying long chain alcohols, unsaturated alcohols, and phenols to give their corresponding β-keto esters in high yields. For the first time, transthiolesterification of β-keto esters with a variety of thiols has been achieved under catalytic conditions. Clay also catalyzes selective transesterification of β-keto esters by primary alcohols in the presence of secondary and tertiary alcohols giving corresponding β-keto esters. A systematic study involving the reactivity of different nucleophiles (alcohols, amines, and thiols) toward β-keto esters is also described. Sterically hindered carbonyl groups as well as α,β-unsaturated carbonyl groups underwent protection without the deconjugation of the double bond. Chemosele...