標題: Thiazole and thiophene analogues of donor-acceptor stilbenes: Molecular hyperpolarizabilities and structure-property relationships
作者: Breitung, EM
Shu, CF
McMahon, RJ
應用化學系
Department of Applied Chemistry
公開日期: 16-Feb-2000
摘要: We calculate the first hyperpolarizability (beta) of several thiazole and thiophene analogues of donor-acceptor stilbene compounds using the ZINDO (sum-over-states) formalism. Because of the inherent dipolar nature of thiazole, in which C2 is electron-poor and C5 is electron-rich, the relative orientation of the thiazole subunit in the dipolar chromophore dramatically affects the nonlinear optical properties. In the "mismatched" case, the dipole of the thiazole ring opposes the molecular dipole created by the donor-acceptor substituents, while in the "matched" case, the dipole of the thiazole ring reinforces the molecular dipale. The hyperpolarizability of the "mismatched" monothiazole 2 (beta(mu) = 68 x 10(-30) cm(5) esu(-1)) exceeds that of stilbene 1 (beta(mu) = 34 x 10(-30) cm(5) esu(-1)) but is smaller than that of monothiophene 4 (beta(mu) = 90 x 10(-30) cm(5) esu(-1)). By contrast, the hyperpolarizability of the "matched" monothiazole 3(beta(mu) = 177 x 10(-30) cm(5) esu(-1)) exceeds not only that of the "mismatched" monothiazole 2, but also that of monothiophene 4. Substituting thiazole for both aryl rings of stilbene produces very large hyperpolarizabilities in the "matched-matched" case (e.g., bis-thiazole 24, beta(mu) = 254 x 10(-30) cm(5) esu(-1)). The nonlinear optical response of heterocyclic analogues of donor-acceptor stilbene derivatives is discussed in terms of the difference in aromatic delocalization energy between phenyl, thiophene, and thiazole, the electronic nature of the heteroaromatic rings, and conformational factors.
URI: http://dx.doi.org/10.1021/ja9930364
http://hdl.handle.net/11536/30723
ISSN: 0002-7863
DOI: 10.1021/ja9930364
期刊: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
Volume: 122
Issue: 6
起始頁: 1154
結束頁: 1160
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