Search results for "Intermolecular"
showing 10 items of 396 documents
Sheets of alternating chirality in the structure of a novel iron(III) complex with a cyclic oxamide ligand
1998
An organic–metalloorganic analogue of the inorganic clay minerals has been obtained from the cyclization of N,N′-bis(ethoxalyl)phenylenediamine in basic medium in the presence of iron(III) ions leading to formation of a cyclic oxamide ligand (L). The combination of intramolecular (covalent) interactions between metal and ligand and intermolecular (noncovalent) ionic interactions creates a novel layered compound with an intriguing crystal structure (shown on the right).
Systematic Modulation of the Supramolecular Gelation Properties of Bile Acid Alkyl Amides
2018
The self-assembly properties of nine low-molecular-weight gelators (LMWGs) based on bile acid alkyl amides were studied in detail. Based on the results, the number of hydroxyl groups attached to the steroidal backbone plays a major role in the gelation, although the nature of the aliphatic side chain also modulates the gelation abilities. Of the 50 gel systems studied, 35 are based on lithocholic acid and 15 on cholic acid derivatives. The deoxycholic acid derivatives did not form any gels. The gelation occurred primarily in aromatic solvents and the gels manifested typical fibrous or spherical morphologies. The 13C cross-polarized magic angle spinning (CPMAS) NMR spectra measured on the cr…
Interactions of α-tocopherol with biomembrane models: Binding to dry lecithin reversed micelles
2005
Abstract The state of α-tocopherol (Vitamin E) in solutions of dry lecithin reversed micelles dispersed in an apolar medium has been investigated as a function of the Vitamin E to surfactant molar ratio (RVE) at fixed surfactant concentration by FT-IR, 1H NMR and SAXS with the aim to emphasize the role played by anisotropic intermolecular interactions and confinement effects as driving forces of its partitioning between apolar bulk solvent and polar nanodomains and of mutual Vitamin E/reversed micelle effects. It has been found that its binding strength to reversed micelles, triggered by steric and orientational constrains, is mainly regulated by specific interactions between the hydrophili…
Multiple points of view of heteronuclear NOE: long range vs short range contacts in pyrrolidinium based ionic liquids in the presence of Li salts.
2015
The nuclear Overhauser enhancement (NOE) is a powerful tool of NMR spectroscopy extensively used to gain structural information in ionic liquids (ILs). A general model for the distance dependence of intermolecular NOE in ILs was recently proposed showing that NOE spots beyond the first solvation shell and accounts for long-range effects. This conclusion prompted for a deep rethinking of the NOE data interpretation in ILs. In this paper we present an extensive and quantitative study of N-propyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI), the homologue with bis(fluorosulfonyl)imide (PYR13FSI), and their mixtures with LiTFSI based on 1H-19F and 1H-7LiNOE correlation …
Halogen⋯halogen interactions in the self-assembly of one-dimensional 2,2′-bipyrimidine-based CuIIReIV systems
2018
Two one-dimensional CuIIReIV coordination polymers of the general formula {[ReIVCl4(μ-bpym)CuIIX2]·solvent}n [where bpym = 2,2′-bipyrimidine, X = Cl (1) and Br (2), and solvent = H2O (1) and CHCl3 (2)] have been prepared and characterised structurally and magnetically. Both compounds crystallise in the monoclinic system with space groups P21/c (1) and P21/n (2). Each CuII ion is bonded to two cis nitrogen atoms from the bpym ligand and to four halogen atoms. Two of these halogen atoms are placed in the equatorial plane and the other two are filling the axial positions of the CuII ion, thus generating a distorted octahedral environment for this metal ion in 1 and 2. In both compounds, the Re…
Intermolecular hydrogen bonding H···Cl− in the solid palladium(II)-diaminocarbene complexes
2017
Abstract Weak intermolecular non-covalent H···Cl− interactions in the solid chelated palladium(II)-diaminocarbene complex cis-[PdCl(CNXyl){C(NHXyl)=NHC6H2Me2 NH2}]Cl (3; Xyl=2,6-Me2C6H3) were studied by XRD followed by appropriate DFT calculations. The N–H···Cl contacts for both NH groups in the carbene moiety are different (N1–H···Cl2 3.5258(19), N2–H···Cl2 3.0797(17) Å). The DFT calculations and topological analysis of the electron density distribution within the formalism of Bader’s theory (QTAIM method) were performed for a model cluster of the carbene complex 3. The theoretical data confirmed that the strength of intermolecular HB H···Cl− is different for two NH-protons of the carbene …
Field-induced slow magnetic relaxation in pseudooctahedral cobalt(ii) complexes with positive axial and large rhombic anisotropy
2019
The preparation, X-ray crystal structure, spectroscopic and variable-temperature dc and ac magnetic properties of two six-coordinate cobalt(ii) complexes of formula [Co(bim)4(tcm)2] (1) and [Co(bmim)4(tcm)2] (2) (bim = 1-benzylimidazole, bmim = 1-benzyl-2-methylbenzimidazole and tcm- = tricyanomethanide ion) are reported. 1 and 2 crystallize in the monoclinic P21/n and C2/c space groups with the asymmetric units composed of one tcm- ion and half the [Co(bim)4]2+ and [Co(bmim)4]2+ complex cations, respectively. Their cobalt atoms are in compressed (1)/rhombic (2) CoN6 octahedral environments, the axial positions being occupied by monodentate tricyanomethanide anions. The neutral molecules in…
Solvent-Adaptive Behavior of Oligospirobifluorenes at the Surface of Quartz Crystal Microbalances-A Conformational Process
2017
Oligospirobifluorenes represent promising building blocks for the generation of microporous sensor materials based on their restricted flexibility. The contact with specific solvents leads to a change of the three-dimensional spirobifluorene structure. The single fluorene moieties unfold to an open structure with an increased volume due to intermolecular interactions with the solvent, detectable by NMR spectroscopy. The induced microporosity was further investigated by affinity comparisons of aromatic analytes with high fundamental frequency quartz crystal microbalances.
Hybrid Particle-Field Molecular Dynamics Simulations of Charged Amphiphiles in an Aqueous Environment.
2018
We develop and test specific coarse-grained models for charged amphiphilic systems such as palmitoyloleoylphosphatidylglycerol (POPG) lipid bilayer and sodium dodecyl sulfate (SDS) surfactant in an aqueous environment, to verify the ability of the hybrid particle-field method to provide a realistic description of polyelectrolytes. According to the hybrid approach, the intramolecular interactions are treated by a standard molecular Hamiltonian, and the nonelectrostatic intermolecular forces are described by density fields. Electrostatics is introduced as an additional external field obtained by a modified particle-mesh Ewald procedure, as recently proposed [Zhu et al. Phys. Chem. Chem. Phys.…
Anomalous pressure dependence of the structure factor in 1,4-polybutadiene melts: A molecular dynamics simulation study
2004
Neutron scattering has shown the first diffraction peak in the structure factor of a 1,4-polybutadiene melt under compression to move to larger q values as expected but to decrease significantly in intensity. Simulations reveal that this behavior does not result from loss of structure in the polymer melt upon compression but rather from the generic effects of differences in the pressure dependence of the intermolecular and intramolecular contributions to the melt structure factor and differences in the pressure dependence of the partial structure factors for carbon-carbon and carbon-deuterium intermolecular correlations. This anomalous pressure dependence is not seen for protonated melts.