Search results for "Interaction"

Interaction of 5‐fluorouracil with β‐cyclodextrin: A density functional theory study with dispersion correction

2020

Detailed studies on the stability, interaction, and microstructure of host‐guest complexes in the vacuum of 5‐fluorouracil (5FU) with β‐cyclodextrin (βCD) were performed using B3LYP with the inclusion of Grimme's dispersion correction GD3 term and 6‐31+G(d,p) basis set. Among several studied 1:1 5FU‐βCD complexes, the one placing the keto tautomer of 5FU vertically in the host cavity and forming N‐H···OCD and CO···HOCD hydrogen bonds with hydroxyl groups of the smaller rim of βCD has the highest stability (Eint = −195 kJ/mol). Interestingly, there are no interactions with the inner hydrophobic part of the βCD host cavity. The strength of the intermolecular H‐bonds to the smaller rim of βC…

Structure and Chemical Bonds in Black Ti(C, N, O) Thin Films

2010

Influence of the modification, induced by zirconia nanoparticles, on the structure and properties of polycarbonate

2013

Melt compounding was used to prepare polycarbonate (PC)–zirconia nanocomposites with different amounts of zirconia. The effect of the zirconia loading, in the range of 1–5 wt.%, on the structure, mechanical properties and thermal degradation kinetics was investigated. The zirconia nanoparticle aggregates were well dispersed in the PC matrix and induced the appearance of a local lamellar order in the polycarbonate as inferred by SAXS findings. This order could be a consequence of the intermolecular interactions between zirconia and the polymer, in particular with the quaternary carbon bonded to the methyl groups and the methyl carbon as inferred from the NMR results. The presence of zirconia…

Quantitative measurements of non-covalent interactions with diamond based magnetic imaging

2018

We present a technique employing dielectrophoretic (DEP) manipulation of surface immobilized complexes integrated with a magnetic imaging platform based on nitrogen-vacancy (NV) centers in diamond for the quantitative measurements of non-covalent interactions. The interdigitated microelectrodes closely spaced to the functionalized surface of the diamond plate provide a wide range of applied DEP forces for noninvasive manipulation of various molecular interactions, while the NV layer under the surface reports the unbinding dynamics. Given that biological samples do not present significant magnetic background and do not screen magnetic fields, our approach has many advantages over the fluores…

Hydrogen-Bonded Aggregates of Oligoaramide−Poly(ethylene glycol) Block Copolymers

2010

Rod−coil copolymers with an oligomeric rod aggregate on a nanometer length scale, which is important for many applications like e.g. organic photovoltaics. However, this aggregation behavior and the driving forces such as hydrogen bonding and π−π interactions, as well as the role of side groups, are not yet fully understood. Here, we investigated these noncovalent interactions in oligo(p-benzamide)−poly(ethylene glycol) (OPBA−PEG) copolymers using solid-state NMR supported by wide-angle X-ray scattering (WAXS), differential scanning calorimetry (DSC), and polarization optical microscopy (POM). It was found that longer OPBAs form layered β-sheet-like aggregates and that these are stabilized …

Supramolecular isomerism in spin crossover networks with aurophilic interactions

2004

Assembly of FeII, 3-cyanopyridine and [Au(CN)2]– affords, in one-pot reaction, three coordination polymers that represent a genuine example of supramolecular isomerism with strong influence in the spin crossover regime of the FeII ions. Real Cabezos, Jose Antonio, Jose.A.Real@uv.es

Controlling the wetting properties of the Asakura-Oosawa model and applications to spherical confinement.

2012

We demonstrate for the Asakura-Oosawa model and an extension of this model that uses continuous rather than hard potentials, how wetting properties at walls can be easily controlled. By increasing the interaction range of the repulsive wall potential acting on the colloids (while keeping the polymer-wall interactions constant) polymers begin to substitute colloids at walls and the system can be driven from complete wetting of colloids via partial wetting to complete wetting of polymers. As an application, we discuss the morphology and wetting behavior of colloid-polymer mixtures in spherical confinement. We apply the recently developed 'ensemble switch method' where the Hamiltonian is exten…

A quantum mechanics/molecular mechanics study of the protein-ligand interaction for inhibitors of HIV-1 integrase.

2007

Human immunodeficiency virus type-1 integrase (HIV-1 IN) is an essential enzyme for effective viral replication. Diketo acids such as L-731,988 and S-1360 are potent and selective inhibitors of HIV-1 IN. In this study, we used molecular dynamics simulations, within the hybrid quantum mechanics/molecular mechanics (QM/MM) approach, to determine the protein-ligand interaction energy between HIV-1 IN and L-731,988 and 10 of its derivatives and analogues. This hybrid methodology has the advantage that it includes quantum effects such as ligand polarisation upon binding, which can be very important when highly polarisable groups are embedded in anisotropic environments, as for example in metal-c…

Normal-phase (temperature gradient) interaction chromatography – A powerful tool for the characterisation of high molecular weight chain-end function…

2015

Abstract We report here, for the first time, quantitative analysis of end-group functionalisation and the extent of end-group modification of polymers with molar mass up to 200,000 g mol −1 , using a combination of isothermal and temperature gradient interaction chromatography. At such high molecular weights, other common analytical techniques such as MALDI-ToF-MS and NMR spectroscopy are simply unable to offer any quantitative insight into the end-group functionality of polymers. Thus, normal phase isothermal interaction chromatography (NP-IIC) has been used to characterise a series of polystyrene samples, with identical molar mass (c. 90,000 g mol −1 ), each carrying a single chain-end fu…

Molecular aggregation in selected crystalline 1:1 complexes of hydrophobicD- andL-amino acids. IV. TheL-phenylalanine series

2009

The amino acid L-phenylalanine has been cocrystallized with D-2-aminobutyric acid, C(9)H(11)NO(2).C(4)H(9)NO(2), D-norvaline, C(9)H(11)NO(2).C(5)H(11)NO(2), and D-methionine, C(9)H(11)NO(2).C(5)H(11)NO(2)S, with linear side chains, as well as with D-leucine, C(9)H(11)NO(2).C(6)H(13)NO(2), D-isoleucine, C(9)H(11)NO(2).C(6)H(13)NO(2), and D-allo-isoleucine, C(9)H(11)NO(2).C(6)H(13)NO(2), with branched side chains. The structures of these 1:1 complexes fall into two classes based on the observed hydrogen-bonding pattern. From a comparison with other L:D complexes involving hydrophobic amino acids and regular racemates, it is shown that the structure-directing properties of phenylalanine closel…