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Molecular Dynamics and Quantum Chemistry Study on Conformations and Optical Properties of Hydrogen Bonded Dipolar Merocyanine Dyes
KTH, School of Biotechnology (BIO), Theoretical Chemistry.
2009 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 113, no 30, 10271-10276 p.Article in journal (Refereed) Published
Abstract [en]

An earlier proposed strategy to orient two merocyanine dyes in the desirable head-to-tail parallel fashion through multiple hydrogen bonds has been examined by molecular dynamics simulations and quantum chemical calculations. Two different merocyanine dyes dissolved in chloroform solution under various conditions are simulated by molecular dynamics. It is found that two dipolar units can be well connected through various numbers of hydrogen bonds. Although the probability to form the desirable head-to-tail dimer is unfortunately small even under strong poling electric field and low temperature, the formation of unwanted antiparallel structure has been effectively reduced. Typical hydrogen bonded dimers obtained from molecular dynamics simulations have been studied by hybrid density functional calculations. It is found that only the most probable complex can lead to the optical absorption spectrum that is in close agreement with the corresponding experiments. Calculated results for dipole moments of ground and charge transfer states, as well as first hyperpolarizabilities, of three typical complexes have also been provided.

Place, publisher, year, edition, pages
2009. Vol. 113, no 30, 10271-10276 p.
Keyword [en]
URN: urn:nbn:se:kth:diva-13826DOI: 10.1021/jp900864bISI: 000268231000032ScopusID: 2-s2.0-67651213781OAI: diva2:327646
QC20100630Available from: 2010-06-30 Created: 2010-06-29 Last updated: 2010-06-30Bibliographically approved
In thesis
1. Theoretical study on nonlinearoptical properties of organicchromophores in solutions
Open this publication in new window or tab >>Theoretical study on nonlinearoptical properties of organicchromophores in solutions
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Inter-molecular interactions have significant influences on linear and nonlinear optical properties of molecules including one- and two-photon absorptions, emissions, and various high order nonlinear polarizations. The related investigation has become an active and challenging research area. The theoretical structure-to-property relationship obtained from quantum chemical calculations of single organic conjugated molecules often can not be directly applied to real materials in condensed phases. One has to consider the effect of environment, that is, inter-molecular interactions, where the model systems experience in real experiments or applications. The change of molecular conformations under all kinds of interactions and its effects on linear and nonlinear optical properties are the central issue of this thesis.

Special attentions have been paid to symmetrical diamino substituted distyrylbenzene chromophores with different torsional angles, two dipolar merocyanine dyes of various orientations, two isomers of a V-shaped 2-hydroxypyrimidine derivative and their various dimers, and the structural fluctuations of interacting polar chromophores in solutions. Quantum chemical methods in combination with molecular dynamics simulations have been employed to study molecular conformations and optical properties in solutions, in particular the solvent and aggregation effects on one- and two-photon absorption. More specifically, time-dependent density functional theory has been used for all electronic calculations, while the polarizable continuum model and supermolecule approach have also been employed to take into account solvent effects.

Moreover, the propagation of an ultrashort laser pulse through a one-dimensional asymmetric organic molecular medium which possesses large permanent dipole moments has been simulated by solving full Maxwell-Bloch equations using predictor-corrector finite-difference time-domain method. We have focused on the supercontinuum generation of spectra and the formation of attosecond pulses.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 80 p.
Trita-BIO-Report, ISSN 1654-2312 ; 2010:9
two-photon absorption, solvent effects, aggregation effects, molecular dynamics simulation
National Category
Theoretical Chemistry
urn:nbn:se:kth:diva-12748 (URN)978-91-7415-630-0 (ISBN)
Public defence
2010-06-07, FA 31, Roslagstullsbacken 21, Stockholm, 10:00 (English)
QC20100630Available from: 2010-05-12 Created: 2010-05-07 Last updated: 2011-01-21Bibliographically approved

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