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Non-linear absorption of 2,5-dialkynyl thiophenes
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
2005 (English)In: Journal of Physical Organic Chemistry, ISSN 0894-3230, E-ISSN 1099-1395, Vol. 18, no 5, 426-433 p.Article in journal (Refereed) Published
Abstract [en]

Three diarylalkynyl-substituted thiophenes were synthesized and the optical power limiting (OPL) effect at 532 nm was investigated for solutions of these compounds. The relationship between the OPL and parameters obtained from molecular-orbital-based calculations is discussed. Semi-empirical calculations indicate that the compounds can have a broad distribution of conformations due to inter-ring twisting, but that the second hyperpolarizability (gamma) can be significant despite a ring twist. The calculations imply that substitution by alkyl groups can lead to enhanced gamma values. The measurements and calculations show a greater increase of the OPL and gamma effects from compound 5 to 6 than from 6 to 7. For these compounds, which differ mainly by the length of the pi-electron system, the magnitude of non-linear absorption seems to be well correlated with several properties of the electronic ground state estimated by standard ab initio molecular orbital calculations, as well as with gamma values from the semi-empirical calculations.

Place, publisher, year, edition, pages
Chichester, Sussex, England: Wiley , 2005. Vol. 18, no 5, 426-433 p.
Keyword [en]
optical limiting, non-linear absorption, hyperpolarizability, thiophenes, thiophenyl, phenylacetylenes
URN: urn:nbn:se:umu:diva-5634DOI: doi:10.1002/poc.881OAI: diva2:145215
Available from: 2007-01-04 Created: 2007-01-04 Last updated: 2011-03-03Bibliographically approved
In thesis
1. Organic and organometallic compounds for nonlinear absorption of light
Open this publication in new window or tab >>Organic and organometallic compounds for nonlinear absorption of light
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The demand for protection of eyes and various types of optical sensors from laser-beam pulses has resulted in the search for optical limiting devices that have the property of being transparent at low intensity of light (normal light), but non-transparent towards high intensity (laser) light. This type of protection may be obtained by using an organic material that displays nonlinear optical (NLO) properties. Examples of NLO effects that can be used for optical limiting are reverse saturable absorption (RSA), two-photon absorption (TPA) and nonlinear refraction.

The advantage of using compounds that show such NLO effects is that they can have very fast response and are self-activating, that is, there is no need for externally controlled switching to obtain optical limiting.

In this work, several dialkynyl substituted thiophenes and some thiophenyl-alkynyl-platinum(II)-complexes were synthesized and tested for nonlinear absorption of light. A palladium-copper mediated coupling (Sonogashira coupling) was utilized for all reactions between terminal alkynes and aryl halides.

Molecular orbital calculations were used in order to screen for suitable properties, such as the second hyperpolarizability, in compounds of interest.

A quantitative structure-activity relationship (QSPR) study using a PLS approach were performed in order to identify important molecular electronic variables for optical limiting of organic compounds.

Place, publisher, year, edition, pages
Umeå: Kemi, 2007. 84 p.
Organic chemistry, Nonlinear absorption, thiophene, platinum complexes, optical limiting, sonogashira coupling reactions, molecular orbital calculations, Organisk kemi
Research subject
Organic Chemistry
urn:nbn:se:umu:diva-965 (URN)91-7264-243-2 (ISBN)
Public defence
2007-01-26, KB3B1, KBC, Umeå universitet, Umeå, 10:00 (English)
Available from: 2007-01-04 Created: 2007-01-04 Last updated: 2009-09-07Bibliographically approved

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