Search results for "MOLECULE"
showing 10 items of 5162 documents
Crystal Engineering Applied to Modulate the Structure and Magnetic Properties of Oxamate Complexes Containing the [Cu(bpca)]+ Cation
2016
This work deals with the crystal engineering features of four related copper(II)-based compounds with formulas {[{Cu(bpca)}2(H2ppba)]·1.33DMF·0.66DMSO}n (2), [{Cu(bpca)(H2O)}2(H2ppba)] (3), [{Cu(bpca)}2(H2ppba)]·DMSO (4), and [{Cu(bpca)}2(H2ppba)]·6H2O (5) [H4ppba = N,N′-1,4-phenylenebis(oxamic acid) and Hbpca = bis(2-pyridylcarbonyl)amide] and how their distinct molecular and crystal structures translate into their different magnetic properties. 2 and 3 were obtained through the hydrolytic reaction of the double-stranded oxamato-based dipalladium(II) paracyclophane precursor of formula [{K4(H2O)2}{Pd2(ppba)2}] (1) with the mononuclear copper(II) complex [Cu(bpca)(H2O)2]+, either in a water…
Organic chelate-free and azido-rich metal clusters and coordination polymers from the use of Me3SiN3: a new synthetic route to complexes with beautif…
2019
In this Feature Article, we highlight the feasibility of a new, recently developed approach towards the synthesis of high-spin molecules and single-molecule magnets (SMMs). The key to the preparation of such molecular compounds is the organic azide precursor Me3SiN3, which fosters the formation of 3d-metal azido clusters and coordination polymers without requiring the assistance of any organic chelating/bridging group. All the isolated compounds contain metallic cores which are surrounded by end-on bridging N3− groups. Consequently, the reported molecular materials exhibit ferromagnetic exchange interactions between the spin carriers, resulting in the stabilization of the maximum possible s…
Chalcogen‐Bonding Interactions in Telluroether Heterocycles [Te(CH2)m]n(n=1–4;m=3–7)
2020
The Te⋅⋅⋅Te secondary bonding interactions (SBIs) in solid cyclic telluroethers were explored by preparing and structurally characterizing a series of [Te(CH2 )m ]n (n=1-4; m=3-7) species. The SBIs in 1,7-Te2 (CH2 )10 , 1,8-Te2 (CH2 )12 , 1,5,9-Te3 (CH2 )9 , 1,8,15-Te3 (CH2 )18 , 1,7,13,19-Te4 (CH2 )20 , 1,8,15,22-Te4 (CH2 )24 and 1,9,17,25-Te4 (CH2 )28 lead to tubular packing of the molecules, as has been observed previously for related thio- and selenoether rings. The nature of the intermolecular interactions was explored by solid-state PBE0-D3/pob-TZVP calculations involving periodic boundary conditions. The molecular packing in 1,7,13,19-Te4 (CH2 )20 , 1,8,15,22-Te4 (CH2 )24 and 1,9,17,…
Insights into the Synthesis and the Solution Behavior ofmeso-Aryloxy- and Alkoxy-Substituted Porphyrins
2015
meso-RO-appended (R = alkyl, aryl) porphyrins bearing one or two OR substituents at the tetrapyrrolic macrocycle were synthesized in good yields from 5,15-dibromo-10,20-diphenylporphyrins 2H(Br2DPP), Ni(Br2DPP) and Zn(Br2DPP) using an SNAr reaction. By varying the solvent, the base, the temperature, and the time of the reaction, the optimum conditions were established, and the selective introduction of one or two meso-RO substituents at the periphery of the macrocycle was achieved. Moreover, monofunctionalization of Ni(Br2DPP) according to an SNAr reaction was used as a key step for the synthesis of rarely explored unsymmetrical porphyrinyl alkyl ethers. 1H NMR studies of these ethers in CD…
Electrochemical Installation of CFH 2 −, CF 2 H−, CF 3 −, and Perfluoroalkyl Groups into Small Organic Molecules
2021
Electrosynthesis can be considered a powerful and sustainable methodology for the synthesis of small organic molecules. Due to its intrinsic ability to generate highly reactive species under mild conditions by anodic oxidation or cathodic reduction, electrosynthesis is particularly interesting for otherwise challenging transformations. One such challenge is the installation of fluorinated alkyl groups, which has gained significant attention in medicinal chemistry and material science due to their unique physicochemical features. Unsurprisingly, several electrochemical fluoroalkylation methods have been established. In this review, we survey recent developments and established methods in the…
Nautilin-63, a novel acidic glycoprotein from the shell nacre of Nautilus macromphalus
2011
In molluscs, and more generally in metazoan organisms, the production of a calcified skeleton is a complex molecular process that is regulated by the secretion of an extracellular organic matrix. This matrix constitutes a cohesive and functional macromolecular assemblage, containing mainly proteins, glycoproteins and polysaccharides that, together, control the biomineral formation. These macromolecules interact with the extruded precursor mineral ions, mainly calcium and bicarbonate, to form complex organo-mineral composites of well-defined microstructures. For several reasons related to its remarkable mechanical properties and to its high value in jewelry, nacre is by far the most studied …
Introduction: Protein Oligomerization and the Formation of Macromolecular Assemblies
2019
The ability of biomolecules to link together to form higher order assemblies underlies much of cellular structure and function. Here we emphasise protein oligomerisation and discuss some of the principles of molecular interaction, from early considerations through to the present day. A few protein examples are presented, selected from our research interests, to highlight assembly features, ranging from the hemoglobins, the hemocyanins to the peroxiredoxins, collagen, the encapsulins and ferritins.
How To Design Selective Ligands for Highly Conserved Binding Sites: A Case Study Using N-Myristoyltransferases as a Model System
2019
A model system of two related enzymes with conserved binding sites, namely N-myristoyltransferase from two different organisms, was studied to decipher the driving forces that lead to selective inhibition in such cases. Using a combination of computational and experimental tools, two different selectivity-determining features were identified. For some ligands, a change in side-chain flexibility appears to be responsible for selective inhibition. Remarkably, this was observed for residues orienting their side chains away from the ligands. For other ligands, selectivity is caused by interfering with a water molecule that binds more strongly to the off-target than to the target. On the basis o…
Synthesis of conformationally restricted 1,2,3-triazole-substituted ethyl β- and γ-aminocyclopentanecarboxylate stereoisomers. Multifunctionalized al…
2010
Abstract Stereoisomers of 1,2,3-triazole-functionalized, conformationally restricted β- or γ-amino esters with a cyclopentane skeleton were efficiently synthetized from the bicyclic β-lactam 6-azabicyclo[3.2.0]hept-3-en-7-one (1) and Vince γ-lactam (15) in five or six steps involving the azide–alkyne 1,3-dipolar cycloaddition of azido-substituted amino ester stereoisomers with nonsymmetric acetylenes. The azide–alkyne click reactions were investigated under thermal and Cu(I)-catalyzed conditions. Surprisingly, the thermally induced cycloaddition furnished the corresponding 1,4-triazoles regioselectively, which also took place selectively in response to Cu(I) catalysis.
Synthesis, crystal structure and magnetic properties of bis[μ-bis(3-(pyridin-2-yl)-1,2,4-triazole-N′,N1,N2)] bis[triaqua nickel(II)] tetranitrate
1998
Abstract A new dinuclear nickel(II) coordination compound of formula Ni2(Hpt)2(H2O)6(NO3)4 (Hpt=3-(pyridin-2-yl)-1,2,4-triazole) was synthesized. The structure was solved at 298 K by single-crystal X-ray analysis. Bisμ-bis(3-(pyridin-2-yl)-1,2,4-triazole-N′,N1,N2) bistriaqua nickel(II) tetranitrate (C14H24N12O18Ni2) crystallizes in the triclinic space group P-1, a=7.2266(1), b=9.9144(1), c=11.2647(1) A, α=66.854(1)°, β=74.000(1)°, γ=86.400(2)°, V=712.42(1) A3, Z=1 (dinuclear units), 2823 reflections (1 > 2σ(I)), R1=0.0442, wR2=0.1197. The Ni(II) ions are bridged by two neutral Hpt ligands coordinating via N1 and N2 in the equatorial plane, Ni(1)-Ni(1)′=4.098(1) A. The Hpt bridging mode is a…