The syntheses, structures and nonlinear optical and related properties of salts with julolidinyl electron donor groups
Abstract
Twelve, dipolar cations with 2,3,6,7-tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl (julolidinyl, Jd) electron donor groups and N-methyl/arylpyridinium, N-methylquinolinium or N-methylbenzothiazolium acceptor groups were synthesised. The chromophores were characterised as their PF^-_6 salts using various techniques including electronic absorption spectroscopy and cyclic voltammetry; single crystal X-ray structures were determined for a large number of salts, all of which form nonpolar materials. A broad correlation between the electron acceptor strength and the degree of bond length alternation is evident. A key focus of this work is detailed comparisons of the Jd-containing chromophores with their previously studied 4-(dimethylamino)phenyl (Dap) analogues. Molecular, quadratic, nonlinear optical responses were determined using femtosecond hyper-Rayleigh scattering at both 1300 and 800 nm, as well as using Stark (electroabsorption) spectroscopic studies of intense, visible π → π* intramolecular charge-transfer bands. Substantial red shifts in the latter transitions are observed on replacing Dap with Jd which indicate that the latter acts as a more effective π-electron donor. With few exceptions, both hyper-Rayleigh scattering and Stark data generally show that using Jd instead of Dap increases the static first hyperpolarizability β_0, in accord with expectations based on the two-state model. β_0 values as high as 6 times larger than that of the chromophore in the technologically important material E-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate are observed.
Additional Information
© 2009 Elsevier. Received 21 October 2008; revised 22 December 2008; accepted 23 December 2008. Available online 3 January 2009. We thank the EPSRC for support (grants GR/M93864 and EP/D070732 and a PhD studentship to ECH) and also the Fund for Scientific Research-Flanders (FWO-V, G.0312.08) and the University of Leuven (GOA/2006/3).We thank Dr. John E.Warren (Synchrotron Radiation Source, CCLRC, Daresbury Laboratory, Warrington, WA4 4AD, UK) for assistance with the crystal structure determination of compound [10]BPh_4.Additional details
- Eprint ID
- 15050
- DOI
- 10.1016/j.dyepig.2008.12.010
- Resolver ID
- CaltechAUTHORS:20090814-141122835
- GR/M93864
- Engineering and Physical Sciences Research Council (EPSRC)
- EP/D070732
- Engineering and Physical Sciences Research Council (EPSRC)
- G.0312.08
- Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO)
- GOA/2006/3
- University of Leuven
- Created
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2009-08-17Created from EPrint's datestamp field
- Updated
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2021-11-08Created from EPrint's last_modified field