Abstract

A computational (ZINDO) investigation is employed to estimate the molecular hyperpolarizability (β) of a [(TTF-NH 2 ) 8 ] (TTF ) tetrathiafulvalene) octameric stack at various fractional (0 < F < 1) oxidation states of TTF F+ . While the neutral [(TTF-NH 2 ) 8 ] octamer exhibits a modest (7.6 × 10 -30 cm 5 esu -1 ) static β 0 value, in relation to a nearly centrosymmetric electronic structure, the formal (TTF-NH 2 ) 0.25+ oxidation state leads to a giant (β 0 ) 3891 × 10 -30 cm 5 esu -1 per octamer) NLO response. This effect
is related to the appearance of an extremely intense HOMO f LUMO-based low-lying transition, occurring at 1260 nm upon fractional oxidation, thus providing new and unexpected interest in TTF-donor substituted molecules. To illustrate the chemical feasibility of such species, two kinds of derivatives are synthesized: a TTF-dimethylaniline (TTF-DMA) by using in particular a Suzuki cross-coupling reaction between iodo-TTF and -dimethylaminophenylboronic acid and a TTF-vinyldimethylaniline (TTF-VDMA) by a Wittig-type condensation notably between TTF-carboxaldehyde and p-(dimethylamino)benzyltri-
phenylphosphonium bromide. Their NLO response, evaluated at 1.064 μm by the Hyper Raleigh Scattering technique, leads to β values around 240 × 10 -30 cm 5 esu -1 , in both cases. Additionally, these monomeric species 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 into oligomeric stacks in the solid state.

Information

Item Type:	Journal
Divisions:	» Laboratory for Terrestrial and Aquatic Ecosystems » Faculty of Science and Technology
ePrint ID:	212
Date Deposited:	2014-12-14
Further Information:	Google Scholar
URI:	https://www.univ-soukahras.dz/en/publication/article/212

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