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4 results on '"short-range intermolecular interactions"'

1. Effects of Electrostatic Interactions on Orientational Order of Solutes in Nematic Solvents: NMR Experiments and Theoretical Predictions

Author

Marcello Longeri, Giuseppina De Luca, Giorgio Moro, Giorgio Celebre, Andrea di Matteo, and Alberta Ferrarini

Subjects
short-range intermolecular interactions, proton dipolar couplings, orientational order parameters, Dielectric, aromatic solutes, NMR in liquid crystals, reaction field, molecular polarizability, atomic charges, molecular surface, ab initio calculations, Polarizability, Liquid crystal, Ab initio quantum chemistry methods, Computational chemistry, General Materials Science, Physics::Chemical Physics, Anisotropy, Chemistry, Molecular orbital theory, General Chemistry, Condensed Matter Physics, Electrostatics, Condensed Matter::Soft Condensed Matter, NMR spectra database, Chemical physics
Abstract

The orientational order parameters of four aromatic solutes in nematic solvents, derived from proton dipolar couplings in NMR spectra, show a correlation with the dielectric anisotropy of the solvents. Explanation of the experimental behaviour is provided by a molecular theory based on the reaction field approximation.

Published
2002

2. Correlation between Molecular Structure and Helicity of Induced Chiral Nematics in Terms of Short-Range and Electrostatic−Induction Interactions. The Case of Chiral Biphenyls

Author

Gian Piero Spada, Steve M. Todd, Andrea di Matteo, Alberta Ferrarini,† and, Giovanni Gottarelli, Guy Solladie, Vance E. Williams, and Robert P. Lemieux

Subjects
short-range intermolecular interactions, High Energy Physics::Lattice, helical twisting power, surface chirality model, Biochemistry, Catalysis, Colloid and Surface Chemistry, chiral biphenyls, Liquid crystal, reaction field, Atom, Molecule, chiral dopants, Anisotropy, molecular helicity and phase helicity, biaxiality of order, Dopant, Condensed matter physics, induced cholesterics, electrostatic intermolecular interactions, order parameters, molecular polarizability, atomic charges, ab initio calculations, rod-like and disc-like behavior, Chemistry, General Chemistry, Electrostatic induction, Helicity, Chirality (chemistry)
Abstract

The helical structure of the chiral nematic phases induced by chiral dopants in nematic solvents provides a macroscopic image of the molecular chirality of the dopant promoted by the orientational order. Chiral biphenyls are challenging systems because their twisting ability shows a strong dependence on the molecular structure, which does not conform to empirical correlation rules. This points out the need for adequate interpretative tools, able to establish a link between molecular properties and macroscopic response. In this paper the twisting ability of chiral biphenyls is reviewed, by reporting examples taken from the literature together with some new experimental results. The microscopic origin of the observed behavior is explained in terms of chirality and anisotropy of short-range and electrostatic-induction interactions. These are described, respectively, by a shape model and a reaction field method, having the common characteristics of a realistic representation of the structure and properties of the chiral dopants in terms of molecular surface, atom charges, and distributed polarizabilities.

Published
2001

3. Effects of Electrostatic Interactions on Orientational Order of Solutes in Liquid Crystals

Author

and Alberta Ferrarini, Giorgio J. Moro, and Andrea di Matteo

Subjects
chemistry.chemical_classification, short-range intermolecular interactions, molecular shaped cavity, aniotropic interactions, Dielectric, Electrostatics, Surfaces, Coatings and Films, chemistry, electrostatic intermolecular interactions, Computational chemistry, Chemical physics, Liquid crystal, reaction field, Materials Chemistry, Non-covalent interactions, Molecule, Physical and Theoretical Chemistry, Reaction field
Abstract

A mean-field model for the analysis of electrostatic interactions in liquid crystal phases is proposed. The model is based on a realistic description of the probe molecule and a continuum approximation for its environment. Electrostatic interactions, treated with the reaction field model, are superimposed to short-range interactions, which are accounted for by a shape method. The model is used to predict orientational order parameters of some representative solutes, characterized by different shapes and charge distributions, dissolved in nematics with different dielectric permittivities.

Published
2000

4. Investigation of internal and external potentials acting on benzyl halides dissolved in different nematic solvents

Author

Marcello Longeri, G. De Luca, Alberta Ferrarini, and Giorgio Celebre

Subjects
Steric effects, Chemistry, SOLUTE-SOLVENT INTERACTIONS, SHORT-RANGE INTERMOLECULAR INTERACTIONS, ELECTROSTATIC INTERMOLECULAR INTERACTIONS, NMR spectroscopy, molecular electric dipole and quadrupole, benzyl halides, nematic solvents, torsional potentials, order parameters, Biophysics, Halide, Condensed Matter Physics, Ring (chemistry), NMR spectra database, Solvent, Mean field theory, Computational chemistry, Liquid crystal, Physical chemistry, Physical and Theoretical Chemistry, Molecular Biology, Electric field gradient
Abstract

The NMR spectra of C6H5CH2X (X=Cl, Br, I) dissolved in three different nematic liquid crystal solvents were analysed to investigate, using the AP-ELS model, the internal and external potentials acting on the solutes. The nematics [ZLI1132, I35 and a zero electric field gradient mixture (55% ZLI1132:EBBA)] were selected to compare the effects depending on the nature of the solvents on both potentials. The internal potential for the rotation around the exocyclic C—C bond shows minima located at γ4=±90° (C—X bond lies in a plane perpendicular to the ring) and torsional barrier increasing with the steric hindrance of the halide (from X=Cl to X=I) and with the polarity of the solvent (I35

Published
1994

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