The syntheses, structures and nonlinear optical and related properties of salts with julolidinyl electron donor groups

Benjamin J. Coe, Simon P. Foxon, Elizabeth C. Harper, James A. Harris, Madeleine Helliwell, James Raftery, I. Assberghs, Koen Clays, Edith Franz, Bruce S. Brunschwig, Anthony G. Fitch

    Research output: Contribution to journalArticlepeer-review


    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 PF6- 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 β0, in accord with expectations based on the two-state model. β0 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. © 2009 Elsevier Ltd. All rights reserved.
    Original languageEnglish
    Pages (from-to)171-186
    Number of pages15
    JournalDyes and pigments
    Issue number2
    Publication statusPublished - Aug 2009


    • Hyper-Rayleigh scattering
    • Julolidinyl dyes
    • Nonlinear optics
    • Organic synthesis
    • Stark spectroscopy


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