Issue 43, 2002

Exploiting structure/property relationships in organic non-linear optical materials: developing strategies to realize the potential of TCNQ derivatives

Abstract

The intrinsic relationship between molecular structure and non-linear optical (NLO) properties is exploited with regard to materials for use in second-harmonic generation (SHG). A bond-length-alternation (BLA) study is performed on all available crystal structures of tetracyanoquinodimethane (TCNQ) derivatives in order to predict better SHG contenders. This builds upon a previous bond-length-alternation study that was carried out on a series of TCNQ derivatives. There, a formalism was derived to calculate the relative level of delocalisation within the central TCNQ fragment and relate this to the molecular hyperpolarizability, β, the measure of the SHG coefficient on the molecular scale. This formalism is based upon the ‘strength–length’ relationship in bonds that has been validated via a charge-density study on one of these TCNQ derivatives using a topological approach. The results of the study are grouped according to the relative levels of delocalisation present in each molecule and compared with known SHG contenders.

The promise of TCNQ derivatives for non-linear optics lies partly in their typically high molecular dipole moments, μ. However, large values of μ usually force the molecules to pack centrosymmetrically in a crystalline environment since the dipoles oppose each other in close proximity, and centrosymmetry precludes any SHG effect since this property is a third-rank tensor. A strategy for forming these materials in a solid-state head-to-tail arrangement that is regular but not crystalline is therefore highly desirable. A feasibility study on the adsorption of a TCNQ derivative into zeolite, ZSM-5, shows that this objective may be achievable in this class of materials, thus providing a mechanism for realizing the potential of highly SHG-active materials identified in the bond-length-alternation study.

Article information

Article type
Paper
Submitted
05 мар 2002
Accepted
24 апр 2002
First published
15 юли 2002

CrystEngComm, 2002,4, 232-238

Exploiting structure/property relationships in organic non-linear optical materials: developing strategies to realize the potential of TCNQ derivatives

J. M. Cole and S. Kreiling, CrystEngComm, 2002, 4, 232 DOI: 10.1039/B202287G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements