Search results for "Molecule"
showing 10 items of 5162 documents
Triazolopyridines. Part 9. The synthesis of7-amino(1,2,3)triazolo(1,5-a)pyridines
1989
Abstract Regiospecific lithiation of (1,2,3) triazolo(1,5-a)pyridines (1) and (4) with subsequent reaction with styryl azide gave small yields of the 7-aminotriazolopyridines (6) and (7). A longer larger scale synthesis of compounds (6) and (7) is described giving overall yields of 17 and 25%, starting from 2-amino-6-methyl (9) or 2-amino-6-ethyl pyridine (19).
Design of guanidinium porphyrins as potential G-quadruplex ligands
2012
We report herein an easy and smooth synthesis of two novel tetra-meso-substituted porphyrins bearing terminal guanidinium functionalities. These two guanidine derivatives are the porphyrin-based analogs of ZnPC , a closely related phthalocyanine-based molecule with four guanidinium arms already reported as an efficient G-quadruplex ligand.
Bisfunctionalized Janus Molecules
2004
[reaction: see text] Bisfunctionalized dendritic multiester molecules were synthesized by combined protection-deprotection and divergent-convergent-divergent sequences in high yields leading to dendritic molecules that combine two functionally different surfaces, polar aliphatic arborol and nonpolar gallate ether moieties, resulting in a two-faced Janus molecule.
The reaction of amino-imidazoles, -pyrazoles and -triazoles with α,β-unsaturated nitriles
2005
The reactions of α,β-unsaturated nitriles (1, 9, 12) as bielectrophiles with aminoazoles (2, 4, 6) as binu-cleophiles were investigated. Acrylonitrile (1) reacts almost exclusively in a chemoselective Michael-type addition yielding the substituted azoles 3, 5 and 7, respectively. Cinnamonitriles 9a,b behave in a similar way, but the free CN group adds a second molecule 4 yielding 10a,b and its cyclocondensation product 11a,b as minor component. The attempted formation of azolopyrimidines is best achieved by the reaction of the benzylidenemalononitriles 12a - f with 2 or 4. The process is chemo- and regioselective. The structure determinations were based on NMR measurements including DEFT, C…
Gold assisted oxygen dissociation on a molybdenum-doped CaO(001) surface
2016
Using density functional theory (DFT) calculations, we address the adsorption of O2 and the coadsorption of gold species and oxygen molecules on a Mo-doped CaO(001) surface with 1.25% impurity concentration. With the help of the Born–Haber thermodynamic cycle, the enhanced binding of an oxygen molecule on Ca(Mo)O is attributed to energy gain owing to simultaneous electron transfer from the dopant to the molecule and lattice relaxations. We consider three coadsorption structures for an Au atom and O2 molecule with different Au–O2 distances. The calculations demonstrate that the coadsorption structures take one electron from the dopant and the O–Au–O chain structure is thermodynamically more …
Non-covalent graphene nanobuds from mono- and tripodal binding motifs.
2017
Graphene nanobuds were prepared via the non-covalent anchoring of C60-based molecules endowed with one or three pyrene units, respectively. TGA, FTIR, UV-Vis and TEM investigations confirmed the formation of nanohybrids. For the two molecular derivatives, striking differences were determined in their interaction with graphene or carbon surfaces by Raman, cyclic voltammetry and molecular mechanics calculations, revealing the important role of pyrene adsorption in modulating the electronic properties of the nanohybrids.
Photochemistry of the H2O/CO System Revisited : The HXeOH···CO Complex in a Xenon Matrix
2017
We report on the complex of a noble-gas hydride HXeOH with carbon monoxide. This species is prepared via the annealing-induced H + Xe + OH···CO reaction in a xenon matrix, the OH···CO complexes being produced by VUV photolysis of the H2O···CO complexes. The H–Xe stretching mode of the HXeOH···CO complex absorbs at 1590.3 cm–1 and it is blue-shifted by 12.7 cm–1 from the H–Xe stretching band of HXeOH monomer. The observed blue shift indicates the stabilization of the H–Xe bond upon complexation, which is characteristic of complexes of noble-gas hydrides. The HXeOH···CO species is the first complex of a noble-gas hydride with carbon monoxide and the second observed complex of HXeOH. On the ba…
Towards oxalate-bridged iron(ii), cobalt(ii), nickel(ii) and zinc(ii) complexes through oxotris(oxalato)niobate(v): an open air non-oxidizing synthet…
2018
Four compounds with the formula [M2(dmphen)4(μ-C2O4)](ClO4)2·2dmso [M = Fe (1), Co (2) and Zn (4); dmphen = 2,9-dimethyl-1,10-phenanthroline] and [Ni2(dmphen)4(μ-C2O4)]3[NbO(C2O4)3]2·16H2O (3) have been synthesized using the tris(oxalato)oxoniobate(V) complex anion as the oxalate source, and their structures have been determined by single crystal X-ray diffraction. X-ray quality crystals of highly insoluble oxalate-bridged species were obtained by taking advantage of the slow release of oxalate by the tris(oxalato)oxoniobate(V) complex anion. The structures of 1–4 all contain oxalate-bridged dimetal(II) units with didentate dmphen molecules acting as end-cap ligands; electroneutrality is ac…
Rhodium catalyzed oxidative coupling of salicylaldehydes with diazabicyclic olefins: a one pot strategy involving aldehyde C–H cleavage and π-allyl c…
2013
An efficient one pot strategy for the synthesis of cyclopentene fused chromanone derivatives through the direct oxidative coupling of salicylaldehydes with bicyclic olefins in the presence of a rhodium-copper catalyst system is described. This is the first report on the ring opening-ring closing of bicyclic hydrazines via metal catalyzed oxidative coupling reaction.
Spectroscopic, Magnetic, and Electrochemical Studies of a Dimeric N-Substituted-Sulfanilamide Copper(II) Complex. X-ray and Molecular Structure of th…
1997
A copper(II) complex of formula Cu(2)(stz)(4) (stz(-) = sulfathiazolato) has been synthesized and characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic system, space group P2(1)cn with a = 10.595(7) Å, b = 14.274(3) Å, c = 29.65(1) Å, and Z = 4. The structure consists of dinuclear copper(II) units which contain four sulfathiazolato ligands bridging the metal ions through a nonlinear NCN group. The copper atoms are four-coordinated, the chromophore being CuN(4). The Cu.Cu bond distance is 2.671(2) Å. Magnetic susceptibility data in the temperature range 7-300 K show the occurrence of intramolecular antiferromagnetic coupling with 2J = -61.5 cm(-1). …