Molecular interactions and crystal packing in nematogen: Computational thermodynamic approach

Praveen, P. Lakshmi; Ojha, Durga P.

doi:10.1134/s0036024411100190

Cited by 7 publications

(12 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Appropriate modelling of this fundamental molecular feature relies on the possibility of assigning a partial charge to all atomic centres Downloaded by [Eindhoven Technical University] at 01:04 17 November 2014 [27]. Analysis of molecular charge distribution can deliver good information about local electrostatic interactions, which is not possible from an experimental point of view.…”

Section: Molecular Charge Distribution and Phase Stabilitymentioning

confidence: 99%

See 1 more Smart Citation

Semi-empirical analysis on electronic spectra and ultraviolet stability of nematic liquid crystals: effect of solvent and substituent

Praveen¹,

Ojha²

2011

Liquid Crystals

Self Cite

View full text Add to dashboard Cite

To cite this article: P. Lakshmi Praveen & Durga P. Ojha (2011) Semi-empirical analysis on electronic spectra and ultraviolet stability of nematic liquid crystals: effect of solvent and substituent, Liquid Crystals, 38:8, 963-970, A semi-empirical analysis has been carried out on two nematic liquid crystals, 4-cyanophenyl-4 -n-pentylbenzoate (CPPB) and 4-cyanophenyl-4 -n-pentoxybenzoate (CPPOB), using the CNDO/S + CI and INDO/S + CI methods. These methods have been applied to simulate and analyse the electronic structures, spectra and ultraviolet (UV) stability of the systems. Phase stability of the systems has also been studied based on molecular charge distribution. The electronic transitions, absorption wavelength, HOMO and LUMO energies are calculated. Furthermore, UV stability of the molecules is discussed in the light of absorption wavelength and electronic transition oscillator strength (f ). The effect of solvent and substituent on these factors is discussed. A comparison among different solvents is also made. These absorption spectra will provide a valuable database for further computational analysis and the other experimental investigations. IntroductionLiquid crystals represent a class of complex fluids that has opened many doors for us to learn a great deal about molecular interactions [1], phase behaviour, transitions and the art of soft condensed matter. These molecular fluids show specific optical properties due to the anisotropy of molecular organisation [2]. This anisotropy plays an important role in applications of the electrical effect, display devices, spatial modulators, etc. The bulk order in these materials has profound control on the way light [3] and electricity behave in the material. A unique insight into this behaviour provides not only information about the particular material under consideration, but also about the global properties of anisotropic fluids and their relationships to other chemical structures and/or physical phenomena.Despite their various applications [4][5][6][7], liquid crystals (LCs) belonging to the 4-cyanophenyl-4 -n-alkylbenzoate (CPnB) homologous series and their composites are less studied than those from cyanobiphenyl series. The simulation of electronic spectra by computational chemistry tools is particularly appealing since a large number of methods have been elaborated and employed to calculate the molecular vertical excitation energies, absorption wavelength and oscillator strength of electronic transitions.In view of this, methods based on Time Dependent Density Functional Theory (TDDFT)

show abstract

Section: Molecular Charge Distribution and Phase Stabilitymentioning

confidence: 99%

“…Liquid crystals represent a class of complex fluids that has opened many doors for us to learn a great deal about molecular interactions [1], phase behaviour, transitions and the art of soft condensed matter. These molecular fluids show specific optical properties due to the anisotropy of molecular organisation [2].…”

Section: Introductionmentioning

confidence: 99%

Semi-empirical analysis on electronic spectra and ultraviolet stability of nematic liquid crystals: effect of solvent and substituent

Praveen¹,

Ojha²

2011

Liquid Crystals

Self Cite

View full text Add to dashboard Cite

show abstract

“…An appropriate modeling of this fundamental molecular feature relies on the possibility of assigning a partial charge to all atomic centers [24]. Analysis of molecular charge distribution can deliver good information about local electrostatic interactions, which is not possible from an experimental point of view.…”

Section: Molecular Charge Distributionmentioning

confidence: 99%

Structure and electronic absorption spectra of nematogenic alkoxycinnamic acids – a comparative study based on semiempirical and DFT methods

Praveen

Ojha

2011

J Mol Model

View full text Add to dashboard Cite

Structure of nematogenic p-n-Alkoxy cinnamic acids (nOCAC) with various alkyl chain carbon atoms (n = 2, 4, 6, 8) has been optimized using density functional B3LYP with 6-31+G (d) basis set using crystallographic geometry as input. Using the optimized geometry, electronic structure of the molecules has been evaluated using the semiempirical methods and DFT calculations. Molecular charge distribution and phase stability of these systems have been analyzed based on Mulliken and Löwdin population analysis. The electronic absorption spectra of nOCAC molecules have been simulated by employing DFT method, semiempirical CNDO/S and INDO/S parameterizations. Two types of calculations have been performed for model systems containing single and double molecules of nOCAC. UV-Visible spectra have been calculated for all single molecules. The UV stability of the molecules has been discussed in light of the electronic transition oscillator strength (f). The dimer complexes of higher homologues (n = 6, 8) have also been reported to enable the comparison between single and double molecules.

show abstract

“…Optical features in the ultraviolet-visible (UV-Vis) region can often be traced to the excitation of specific types of electrons in a material. Since the most of LC compounds contain an extended conjugated aromatic moiety, spectroscopic measurements such as UV-Vis absorption are considered to be necessary [4], which influences on the desired electronic or optical properties in the bulk liquid crystalline phases of materials [5]. Usually, this is monitored by UV-Vis spectroscopy at the absorption maxima, which implies a destructive read-out of molecular systems.…”

Section: Introductionmentioning

confidence: 99%

Substituent and solvent effects on UV‐visible absorption spectra of liquid crystalline disubstituted biphenylcyclohexane derivatives – a computational approach

Praveen¹,

Ojha²

2011

Cryst. Res. Technol.

Self Cite

View full text Add to dashboard Cite

Key words liquid crystals, absorption spectra, oscillator strength.A computational approach has been carried out on liquid crystalline disubstituted biphenylcyclohexanes (BCHs) of general formula R-C 6 H 10 -C 6 H 4 -C 6 H 4 -X with R: C 3 H 7 ; X: H (BCH30) and R: C 5 H 11 ; X: CN (BCH5CN) using the CNDO/S + CI and INDO/S + CI methods. These methods have been employed to calculate and analyze the spectral shifts, and absorbance measurements in UV-visible range of the systems. The electronic transitions, absorption wavelength, HOMO (Highest Occupied Molecular Orbital), and LUMO (Lowest Unoccupied Molecular Orbital) energies have been calculated. Further, ultraviolet (UV) stability of the molecules has been discussed in the light of absorption wavelength and electronic transition oscillator strength (f). The effect of different solvent media and substituents on transition energies, oscillator strength, and other absorption parameters has also been reported. The present article provides valuable information regarding enhancing the UV stability of molecules by marinating their conductivity. Further, these absorption spectra will provide valuable data base for future computational studies, and the other experimental investigations.

show abstract

Molecular interactions and crystal packing in nematogen: Computational thermodynamic approach

Cited by 7 publications

References 14 publications

Semi-empirical analysis on electronic spectra and ultraviolet stability of nematic liquid crystals: effect of solvent and substituent

Semi-empirical analysis on electronic spectra and ultraviolet stability of nematic liquid crystals: effect of solvent and substituent

Structure and electronic absorption spectra of nematogenic alkoxycinnamic acids – a comparative study based on semiempirical and DFT methods

Substituent and solvent effects on UV‐visible absorption spectra of liquid crystalline disubstituted biphenylcyclohexane derivatives – a computational approach

Contact Info

Product

Resources

About