Search results for "nimi"
showing 10 items of 596 documents
CCDC 1478367: Experimental Crystal Structure Determination
2017
Related Article: Saikat Banerjee, Sattwick Halder, Paula Brandão, Carlos J. Gómez García, Samia Benmansour, Amrita Saha|2017|Inorg.Chim.Acta|464|65|doi:10.1016/j.ica.2017.04.056
CCDC 1815493: Experimental Crystal Structure Determination
2018
Related Article: Ai-Min Li, Eva Rentschler|2018|Polyhedron|154|364|doi:10.1016/j.poly.2018.08.003
Definition of the chalcogen bond (IUPAC Recommendations 2019)
2019
Abstract This recommendation proposes a definition for the term “chalcogen bond”; it is recommended the term is used to designate the specific subset of inter- and intramolecular interactions formed by chalcogen atoms wherein the Group 16 element is the electrophilic site.
Generation and Oligomerization of N-Ferrocenyl Ketenimines via Open-Shell Intermediates
2016
In the presence of oxidant (Ag[SbF6]) and base, N-ferrocenyl thioamide Fc-NHC(S)CH3 (H-1; Fc = Fe(η5-C5H5)(η5-C5H4)) converts in an unexpected multistep reaction sequence to a novel N,S-heterocyclic ring, which initiates an oligomerization reaction. Key intermediates toward the resulting complicated material are Ag6(1)6 silver clusters of the anionic N,S-chelating ligand 1− and EPR-active piano stool complexes resulting from ring-slipped cyclopentadienyl ligands, as well as electrophilic N-ferrocenyl ketenimine Fc-N═C═CH2 (2) and its ferrocenium cation 2•+ formed by hydrosulfide elimination. Mechanistic insight is achieved using X-ray diffraction and mass spectrometry, as well as EPR and NM…
Ethanedithiol diacetate
2001
Ethane-1,2-diyl S,S′-bis(thioacetate), H3CC(O)SCH2CH2SC(O)CH3 or C6H10O2S2, forms centrosymmetric molecules in the solid state and the molecular structure determined by X-ray crystallography is in good agreement with that obtained by density functional geometry optimization. The planarity of the O=C—S—C fragment, which is also found in structures of other thioacetates, is attributed to a strong np(S)–π*(C—O) orbital interaction.
The use of metallocenic esters of n-hydroxysuccinimide for metallohapten synthesis
1991
Different organometallic markers have been described in a new technique for the labelling of many drugs. Thus metallocenic esters of [M = (;CO)3CrC6H5; (;CO)3CrC6H5(;CH2)3; η-C5H5FeC5H4; (;CO)3MnηC5H4; (;CO)3MnηC5H4COCH2CH2; ηC5H4(;ηC5H5)Co+PF−6] react with primary or secondary amine drugs [DRUGNHR] for a psychostimulant drug: amphetamine; tricyclic antidepressants—desipramine and nortriptyline; a vasodilator—histamine; an adrenergic substance—norfenefrine; and for a central stimulant—meth-amphetamine, to give the metallohaptens MCON(;R)—DRUG. All these compounds have been fully characterized by different analytical methods and have potentialities for biological assays. This synthetic route…
Understanding the mechanism of the N-heterocyclic carbene-catalyzed ring-expansion of 4-formyl-β-lactams to succinimide derivatives
2009
The mechanism of the N-heterocyclic carbene (NHC)-catalyzed ring-expansion of 4-formyl-β-lactams to succinimides has been studied using DFT methods at the B3LYP/6-31G∗∗ level. The first step is the nucleophilic attack of NHC to the aldehyde to yield the zwitterionic intermediate, which by a proton-transfer process affords the Breslow intermediate. The lactam N–C breaking bond in this intermediate yields an enol-amidate, which by a keto–enol type equilibrium becomes the ketone form. The subsequent ring-closure achieved by the nucleophilic attack of the amidate to carbonyl carbon allows the formation of the five-membered ring. Finally, elimination of NHC affords the succinimide. Analysis of t…
Hyperbranched polyethylenimine-supported copper(II) ions as a macroliganted homogenous catalyst for strict click reactions of azides and alkynes in w…
2019
Abstract Loading hyperbranched polyethylenimine (PEI) with copper(II) ions leads to the formation of a new water-soluble metallodendritic polymer Cu(II)-PEI that has been found to effectively catalyze the clickable azide-alkyne [3 + 2] cycloaddition reactions in water under ambient conditions, in the lack of any external reducing agent. A positive dendritic effect on the catalyst activity was observed in the click of 1,2,3-triazole by lowering the reduction potential of copper(II) into the in-situ generation of the catalytically active species copper(I). The reaction proceeds straightforwardly to afford the corresponding 1,4-disubstituted-1,2,3-triazole derivatives in a regioselective manne…
Citric Acid Based Carbon Dots with Amine Type Stabilizers: pH-Specific Luminescence and Quantum Yield Characteristics
2020
We report the synthesis and spectroscopic characteristics of two different sets of carbon dots (CDs) formed by hydrothermal reaction between citric acid and polyethylenimine (PEI) or 2,3-diaminopyridine (DAP). Although the formation of amide-based species and the presence of citrazinic acid type derivates assumed to be responsible for a blue emission is confirmed for both CDs by elemental analysis, infrared spectroscopy, and mass spectrometry, a higher abundance of sp2-hybridized nitrogen is observed for DAP-based CDs, which causes a red-shift of the n-π* absorption band relative to the one of PEI-based CDs. These CD systems possess high photoluminescence quantum yields (QY) of ∼40% and ∼48…
Supramolecular Thermotropic Liquid Crystalline Materials with Nematic Mesophase Based on Methylated Hyperbranched Polyethylenimine and Mesogenic Carb…
2006
Supramolecular interaction of fully methylated hyperbranched polyethylenimines (PEI) with a mesogen-based carboxylic acid, 5-(p-cyanobiphenoxy)pentanoic acid, results in the formation of supramolecular complexes exhibiting thermotropic liquid crystalline (LC) mesophases. In contrast to the common smectic mesophases of most dendritic LC polymers, nematic LC phase were observed. The complexation of PEI and the mesogen units is due to electrostatic interaction between the carboxylate groups and the ammonium end groups of PEI. LC properties were investigated by a combination of differential scanning calorimetry, polarizing light optical microscopy, and X-ray diffractometry.