Quadratic Nonlinear Optical Response in Partially Charged Donor-Substituted Tetrathiafulvalene: From a Computational Investigation to a Rational Synthetic Feasibility

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• 作者：Jean Franç ; ois Lam&egrave ; re ; Isabelle Malfant ; Alix Sournia-Saquet ; Pascal G. Lacroix ; Jean Marc Fabre ; Lakhé ; mici Kaboub ; Tahar Abbaz ; Abdel-Krim Gouasmia ; Inge Asselberghs ; Koen Clays
• 刊名：Chemistry of Materials
• 出版年：2007
• 出版时间：February 20, 2007
• 年：2007
• 卷：19
• 期：4
• 页码：805 - 815
• 全文大小：276K
• 年卷期：v.19,no.4(February 20, 2007)
• ISSN：1520-5002

文摘

A computational (ZINDO) investigation is employed to estimate the molecular hyperpolarizability ()of a [(TTF-NH₂)₈] (TTF = tetrathiafulvalene) octameric stack at various fractional (0 < < 1) oxidationstates of TTF⁺. While the neutral [(TTF-NH₂)₈] octamer exhibits a modest (7.6 × 10^-30 cm⁵ esu^-1)static ₀ value, in relation to a nearly centrosymmetric electronic structure, the formal (TTF-NH₂)^0.25+oxidation state leads to a giant (₀ = 3891 × 10^-30 cm⁵ esu^-1 per octamer) NLO response. This effectis related to the appearance of an extremely intense HOMO LUMO-based low-lying transition, occurringat 1260 nm upon fractional oxidation, thus providing new and unexpected interest in TTF-donor substitutedmolecules. To illustrate the chemical feasibility of such species, two kinds of derivatives aresynthesized: a TTF-dimethylaniline (TTF-DMA) by using in particular a Suzuki cross-coupling reactionbetween iodo-TTF and p-dimethylaminophenylboronic acid and a TTF-vinyldimethylaniline (TTF-VDMA)by a Wittig-type condensation notably between TTF-carboxaldehyde and p-(dimethylamino)benzyltriphenylphosphonium bromide. Their NLO response, evaluated at 1.064 m by the Hyper Raleigh Scatteringtechnique, leads to values around 240 × 10^-30 cm⁵ esu^-1, in both cases. Additionally, these monomericspecies are observed to exhibit very strong multiphoton fluorescence in solution after one electron oxidation.Different routes are discussed toward a possible engineering of TTF-donor based chromophores intooligomeric stacks in the solid state.