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251.
Mitrali Biswas Sanchaita Dey Abhishek Das Prof. Dr. Tapan Kanti Paine Dr. Sanjib Panda Prof. Dr. Goutam Kumar Lahiri 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(63):e202202088
The unexplored ‘actor’ behavior of redox-active bis(aldimine) congener, p-phenylene-bis(picoline)aldimine (L1), towards dioxygen activation and subsequent functionalization of its backbone was demonstrated on coordination with {Ru(acac)2} (acac= acetylacetonate). Reaction under aerobic condition led to the one-pot generation of dinuclear complexes with unperturbed L1, imino-carboxamido (L2−), and bis(carboxamido) (L32−)-bridged isovalent {RuII(μ-L1)RuII}, 1/ {RuIII(μ-L32−)RuIII}, 3 and mixed-valent {RuII(μ-L2−)RuIII}, 2 . Authentication of the complexes along with the redox non-innocence behavior of their bridge have been validated through structure, spectroelectrochemistry and DFT calculations. Kinetic and isotope labelling experiments together with DFT analyzed transition states justified the consideration of redox shuttling at metal/L1 interface for 3O2 activation despite of the closed shell configuration of 1 (S=0) to give carboxamido derived 2 / 3 . 相似文献
252.
Das Tushar Kanti Ganguly Sayan Bhawal Poushali Mondal Subhadip Das Narayan Ch 《Research on Chemical Intermediates》2018,44(2):1189-1208
Research on Chemical Intermediates - Silver nanoparticles (AgNPs) were gradually grown on a hydroxyapatite surface via a green self-reducing approach. Hydroxyapatite (HAP) was functionalized by... 相似文献
253.
Dibenzyltin bis(2‐ethylhexanoate) 1 (4‐Y C6H4CH2)2Sn(OC(O)R1)2 [Y = H, 1a; MeO, 1b; Cl, 1c; Me, 1d; and R1 = MeCH2CH2CH2CH(Et) ] were synthesized either from the reaction of corresponding dibenzyltin dichlorides with silver 2‐ethylhexanoate or from the reaction of dibenzyltin oxides with 2‐ethylhexanoic acid. Compound 1a was further utilized as a catalyst for the reaction of mono‐ and di‐isocyanates [PhNCO, CH3C6H3‐2,4‐(NCO)2 and OCN(CH2)6NCO] with alcohols (primary, secondary, tertiary, cyclohexcyl, alkyl, allyl, benzyl and aryl) leading to the formation of the corresponding urethanes. The catalytic efficiencies of 1 vis‐à‐vis industrially known organotin catalysts have been determined through kinetic studies for the reaction of PhNCO and n‐BuOH at various temperatures. Compounds 1a, 1c and 1d show higher efficiency than dibutyltin bis(2‐ethylhexanoate). FTIR studies further provide mechanistic insights into the catalytic cycle, which comprises pre‐coordination of isocyanate to tin(IV), formation of stannyl carbamate and generation of dibenzyl(alkoxy)carboxylate as the active catalyst. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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256.
D.A. Vinnik V.E. Zhivulin D.P. Sherstyuk A.Y. Starikov P.A. Zezyulina S.A. Gudkova D.A. Zherebtsov K.N. Rozanov S.V. Trukhanov K.A. Astapovich V.A. Turchenko A.S.B. Sombra D. Zhou R.B. Jotania C. Singh A.V. Trukhanov 《Materials Today Chemistry》2021
Znx-1NixFe2O4 samples have been synthesized by solid-state reactions. Data on the chemical composition and the surface morphology of the samples have been obtained using a scanning electron microscope. X-ray powder diffractometer has been used to establish the phase purity and to determine the unit cell parameters. It has been found that the obtained samples had the spinel structure with Fd-3m (No. 227) space group. The unit cell parameters decrease with increasing nickel concentration. The magnetic characteristics of the obtained samples are determined and discussed. The Curie point of obtained samples varies in the range of 803.5–572.7 K. The maximum spontaneous magnetization of ~74.6 emu/g at room temperature was fixed for the solid solution with x = 0.6. The maximum value of the μ/real part of ~12 and μ//imaginary part of 6 of the permeability in the frequency range of 50 MHz–10 GHz is observed for the composition with x = 0.3. The composite samples for microwave study were prepared by mixing the ferrite powders with molten paraffin wax. The largest value of the μ/ real part of ~3 and μ// imaginary part of 0.63 of permeability is found for the x = 0.4 composite. The formation of the composite significantly reduces permeability. 相似文献
257.
Cucurbit[n]urils, the pumpkin shaped macrocyclic host molecules possessing a hydrophobic cavity and two identical carbonyl portals, have drawn a lot of attention in recent years due to their high-affinity yet dynamic molecular recognition properties in water. The reversible and stimuli-responsive nature of their host-guest complexes imparts “smart” features leading to materials with intriguing optical, mechanical and morphological properties. In this review, we focus on the design of cucurbituril based luminescent materials in aqueous media as well in solid or film state. The design principles of fluorescent complexes, small assemblies as well as supramolecular polymers along with their stimuli-responsive properties and applications in diverse areas such as optoelectronic devices, light harvesting, anti-counterfeiting and information technology, cell imaging, etc are highlighted with selected examples from recent literature. We also discuss examples of room temperature phosphorescent materials derived from purely organic luminogens in the presence of cucurbiturils. 相似文献
258.
The total synthesis of panaginsene has been accomplished in 11 linear steps starting from methyl 3,3-dimethyl-5-oxocyclopent-1-ene-1-carboxylate. The key steps are a Sharpless asymmetric epoxidation and Ti(III)-mediated reductive epoxide opening-radical cyclization to construct the chiral quaternary carbon stereocenter followed by a very challenging HWE olefination reaction on an 1,3-keto aldehyde and a late stage McMurry olefination using low valent titanium to construct the highly constrained angular tetrasubstituted olefin in a five-membered ring. 相似文献
259.
Yashoda Krishna Sunkari Chandan Pal Thota Jagadeshwar Reddy Tushar Kanti Chakraborty 《Tetrahedron》2014
A convenient protocol is developed for the synthesis of 3′-[N-(fluorenylmethoxycarbonyl)-amino]-5′-carboxymethyl derivatives of all four natural ribonucleosides from cheap chiral pool compound glucose. Synthesis of fully amide-linked RNA analogues of small oligonucleotides containing, for the first time, all four nucleoside amino acids using standard solid phase Fmoc-chemistry is described. 相似文献
260.
Regio‐ and Diastereoselective and Enantiospecific Metal‐Free C(sp3)H Arylation: Facile Access to Optically Active 5‐Aryl 2,5‐Disubstituted Pyrrolidines
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Surajit Haldar Subhra Kanti Roy Bholanath Maity Prof. Dr. Debasis Koley Prof. Dr. Chandan K. Jana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(43):15290-15298
Optically active 5‐aryl 2,5‐disubstituted pyrrolidines are the principal structural moiety of many bioactive compounds including natural products and catalysts for asymmetric synthesis. A highly regio‐ and diastereoselective and enantiospecific method for direct C?H arylation of aliphatic amine has been developed. Structurally diverse enantiopure arylated pyrrolidines were synthesized from commercially available starting materials, through a single‐step three‐component reaction under metal‐ and oxidant‐free conditions. Furthermore, the complex analogous structure of CCK antagonist RP 66803 and angiotensin‐converting enzyme inhibitors was easily constructed using the synthesized arylated pyrrolidine derivative. Detailed theoretical calculations (M06‐2X/TZVPP/SMD//M06‐2X/6‐31+G(d,p) level) were also carried to investigate the mechanism and high level of stereocontrol involved in this direct sp3 C?H arylation reaction. Preference for a given regio‐ and stereoselectivity in the arylated product can be explained through elucidation of the mechanism for dehydration, generating azomethine ylide, and for the final re‐aromatization step. The calculated energies reveals that the re‐aromatization step is essentially rate determining, accompanying an activation barrier of Δ≠${G{{{\rm S}\hfill \atop {\rm L}\hfill}}}$ =25.6 kcal mol?1. 相似文献