Callaghan Innovation Research Papers

Back to Research Papers

TitleSynthesis, linear and quadratic nonlinear optical properties of ionic indoline and N,N-dimethylaniline based chromophores
Publication TypeJournal Article
Year of Publication2011
AuthorsTeshome, A., Bhuiyan M.D.H., Gainsford G.J., Ashraf M., Asselberghs I., Williams G.V.M., Kay A.J., and Clays K.
JournalOptical Materials
Pagination336 - 345
Date Published2011
ISSN09253467 (ISSN)
KeywordsBond length, Chromophores, Counter-anion, Dimethyl sulfoxide, First molecular hyperpolarizability, Hyper-Rayleigh scattering, Ionic organic compounds, Ions, methanol, Naphthalene, Nonlinear optics, Optical materials, Optical properties, Organic solvents, Rayleigh scattering, Second order nonlinear optics, Solvent polarity and bond-length alternation
AbstractThe synthesis, linear and second-order nonlinear optical (NLO) properties of a series of ionic indoline and N,N-dimethylaniline based chromophores are described. In order to optimise the second-order NLO response of these compounds four basic variations to the molecules and/or their environments have been implemented and their effect studied. These consist of changes to the counter-anion (from iodide to p-toluenesulfonate to naphthalene-2-sulfonate), variation of the solvent polarity [dimethyl sulfoxide (DMSO) to methanol (MeOH) to chloroform (CHCl3)], annelation of the acceptor unit (pyridinium to quinolinium) and a change in the donor used (N,N-dimethylaniline to indoline). It is found that the strongest enhancements to the quadratic NLO response occur when the acceptor moiety is changed from pyridinium to quinolinium, while compounds with an indoline donor group are slightly superior to those containing dimethylaniline as donor. There is no real discernable change in the first hyperpolarizability on altering either the counter-anion or solvent used for the measurements. X-ray crystallographic data were obtained for two of the compounds, and they are found to pack in centrosymmetric fashion, and have a small degree of twisting between the donor and acceptor. From this data it is seen that there is a general agreement between the degree of bond-length alternation (BLA) and the NLO response of the chromophores, and that for charged chromophores such as these a BLA value of approximately 0.1 is optimal. © 2010 Elsevier B.V. All rights reserved.

Back to top