Search results for "Bonding"
showing 10 items of 996 documents
A Non-Local Mode-I Cohesive Model for Ascending Thoracic Aorta Dissections (ATAD)
2018
This paper presents a non-local interface mechanical model to describe aortic dissection. In this regard, the mode-I debonding problem based on a cohesive zone modeling is endowed with non-local terms to include long-range interactions that are present in multi-layered biological tissue. Such non-local effects are related to the collagen fibers that transmit forces between non-adjacent elements. Numerical simulations are provided with different values of the non-local parameters in order to show the effect of the non-locality during the debonding processes.
Chiroptical Phenomena in Reverse Micelles: The Case of (1R,2S)- Dodecyl (2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium Bromide (DMEB)
2014
(1R,2S)-Dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) aggregates dispersed in carbon tetrachloride have been investigated by Fourier transform infrared (FT-IR), vibrational circular dichroism (VCD) and 1H nuclear magnetic resonance (NMR) spectroscopy at various surfactant concentration and water-to-surfactant molar ratio. Experimental data indicate that, even at the lowest investigated concentration and in absence of added water, DMEBmolecules associate in supramolecular assemblies. At higherDMEBconcentration the aggregates can confine watermolecules,making it plausible to think thatDMEB form reverse micelles and that watermolecules are quite uniformly distributed…
Crystal structure of the tripeptideN-(benzyloxycarbonyl)glycylglycyl-L-norvaline
2015
The title tripeptide, C17H23N3O6, contains a nonproteinogenic C-terminal amino acid residue, norvaline, which is an isomer of the amino acid valine. Norvaline, unlike valine, has an unbranched side chain. The molecule has a Gly–Gly segment which adopts an extended conformation. The norvaline residue also adopts an extended backbone conformation while its side chain has ag+tconformation. In the crystal lattice, N—H...O and O—H...O hydrogen bonds stabilize the packing. Molecules translated along the crystallographicaaxis associate through an N—H...O hydrogen bond. The remaining three hydrogen bonds are between molecules related by a21screw axis.
Reactivity of bis(cyclohexylammonium) 4-nitrophenylphosphate with SnMe3 Cl. X-ray structure of 4-NO2 C6 H4 PO4(SnMe3)2·H2 O
2014
The reaction of bis(cyclohexylammonium) 4-nitrophenylphosphate with Me3 SnCl (1:2) under reflux in ethanol yielded the title compound 4-NO2 C6 H4 PO4(SnMe3)2H2 O (1). The X-ray crystallographic analysis achieved on single crystals obtained by slow evaporation at room temperature revealed the formation of an unexpected supramolecular coordination network. The elementary building block can be viewed as two Me3 Sn moieties linked by a bridging 4-nitrophenylphosphate ligand. The two tin atoms are five-coordinated and describe a trans-Me3 SnO2 geometry in a trigonal bipyramidal arrangement. However, the Sn atoms are distinct, exhibiting two different environments. Thus, one is linked to two axia…
The first catalytic method for Heck alkynylation of unactivated aryl bromides (copper-free Sonogashira) in an ionic liquid: 1 mol-percent palladium/t…
2007
Herein we report the studies of Heck alkynylation (copper-free Sonogashira) with aryl halides (I, Br, Cl) employing various metallic precursors, tertiary phosphanes and bases in [BMIM][BF4] as the solvent. As a result, we provide the first method that allows the coupling of a large array of substrates, either activated or deactivated bromides in an ionic liquid. Furthermore, the system of highest efficiency is unexpectedly the simplest and cheaper combination that employs [Pd(η3-C3H5)Cl]2/PPh3 at only a 1 mol-% loading with pyrrolidine as the base and in the absence of a copper salt. The coupling of sterically and electronically deactivated bromides bearing different functional groups to ar…
A Model for Assessing the Magnitude and Distribution of Sheath Currents in Medium and High-Voltage Cable Lines
2020
In this article, the authors discuss a simulation model to study the effect of cross-bonding of metallic sheaths, and/or nonmagnetic armors, of single-core medium- and high-voltage cables in the same circuit. In single-core cables, the resistive losses due to the induced circulating currents in cable sheaths or armors cause an increase of the cable temperature, which therefore reduces its ampacity. This is a serious issue affecting the distribution and transmission lines. In addition, the risk of electric shock due to induced voltages may be present if a person is in contact with the armor/sheath at its unbounded end. For these reasons, special bonding techniques of metal sheaths are employ…
The subtle balance of weak supramolecular interactions: The hierarchy of halogen and hydrogen bonds in haloanilinium and halopyridinium salts
2010
The series of haloanilinium and halopyridinium salts: 4-IPhNH₃Cl (1), 4-IPhNH₃Br (5), 4-IPhNH₃H₂PO₄ (6), 4-ClPhNH₃H₂PO₄ (8), 3-IPyBnCl (9), 3-IPyHCl (10) and 3-IPyH-5NIPA (3-iodopyridinium 5-nitroisophthalate, 13), where hydrogen or/and halogen bonding represents the most relevant non-covalent interactions, has been prepared and characterized by single crystal X-ray diffraction. This series was further complemented by extracting some relevant crystal structures: 4-BrPhNH3Cl (2, CCDC ref. code TAWRAL), 4-ClPhNH3Cl (3, CURGOL), 4-FPhNH3Cl (4, ANLCLA), 4-BrPhNH3H2PO4, (7, UGISEI), 3-BrPyHCl, (11, CIHBAX) and 3-ClPyHCl, (12, VOQMUJ) from Cambridge Structural Database for sake of comparison. Bas…
catena-Poly[[diaquabis[1,4-bis(pyridin-4-yl)buta-1,3-diyne-κN]iron(II)]-μ-cyanido-κ2N:C-[dicyanido-κ2C-platinum(II)]-μ-cyanido-κ2C:N]
2017
The molecular structure of the title compound, [FePt(CN)4(C14H8N2)2(H2O)2]n, consists of one-dimensional polymeric [–Fe–NC–Pt(CN)2–CN–]∞chains. Two water molecules and two monodentate 1,4-bis(pyridin-4-yl)buta-1,3-diyne (bpb) ligand molecules complete the octahedral coordination sphere of the FeIIatoms. The Fe—N(py) bond length (py is pyridine) is 2.2700 (15) Å, Fe—N(cyanide) is 2.1185 (16) Å and the Fe—O distance is 2.1275 (14) Å. The water molecules are hydrogen bonded to either bpb ligands or cyanide groups of the planar [Pt(CN)4]2−anion of adjacent polymeric chains. These O—H...N hydrogen bonds, in conjunction with offset and tilted π–π stacking interactions between bpb ligands and cyan…
Crystal structure ofS-octyl (E)-3-(4-methoxybenzylidene)dithiocarbazate
2015
As already observed in similar molecules, the dithiocarbazate group in the title compound, C17H26N2OS2, adopts anEEconfiguration with respect to the C=N bond of the benzylidene moiety. In the crystal, molecules are connected into inversion dimers by pairs of N—H...S hydrogen bonds. The dimers are linked by weak π–π interactions, with centroid-to-centroid distances of 3.723 (11) Å, forming chains parallel to [110].
Crystal structure of (E)-4-[N-(7-methyl-2-phenyl-imidazo[1,2-a]pyridin-3-yl)carboximido-yl]phenol.
2015
The molecule of the title compound, C21H17N3O, is built up from fused five- and six-membered rings connected to a methyl group, a phenyl ring and an (iminomethyl)phenol group. The fused ring system is almost planar (r.m.s. deviation = 0.031 Å) and forms dihedral angles of 64.97 (7) and 18.52 (6)° with the phenyl ring and the (iminomethyl)phenol group, respectively. In the crystal, centrosymmetric molecules are linked by pairs of C—H...π interactions into dimeric units, which are further connected by O–H...N hydrogen bonds to form layers parallel to (101).