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Article Dans Une Revue Chemistry - A European Journal Année : 2024

From Stilbenes to carbo‐Stilbenes: an Encouraging Prospect

Alix Sournia-Saquet
Valérie Maraval
Christian Bijani
Xiuling X Cui
Albert Poater
Remi R Chauvin

Résumé

Beyond previously described carbo-naphthalene and carbo-biphenyl, a novel type of bis-carbo-benzenic molecules is envisaged from the stilbene parent. The synthesis, structure, spectroscopic and electrochemical properties of two such carbo-stilbenes are described at complementary experimental and computational DFT levels. In the selected targets, the bare skeletal carbo-mer of carbo-stilbene is decorated by 8 or 10 phenyl groups, 0 or 2 tert-butyl groups, and 2 n-octyl chains, the later substituents being introduced to compensate anticipated solubility issues. As in the parent stilbene series, isomers of the phenylated carbo-stilbenes are characterized. The cis- and trans-isomers are, however, formed in almost equal amounts and could not be separated by either chromatography or crystallization. Nevertheless, due to a slow interconversion at the NMR time scale (up to 55 °C) the 1H NMR signals of both isomers of the two carbo-stilbenes could be tentatively assigned. The calculated structure of the cis-isomer exhibits a helical shape, consistent with the observed magnetic shielding of phenyl p-CH nuclei residing inside the shielding cone of the facing C18 ring. The presence of the two isomers in solution also gives rise to quite broad UV-vis absorption spectra with main bands at ca 460, 560 and 710 nm, and a significant bathochromic shift for the decaphenylated carbo-stilbene vs the di-tert-butyl-octaphenylated counterpart. Square wave voltammograms do not show any resolution of the two isomers, giving a reversible reduction wave at −0.65 or −0.58 V/SCE, and an irreversible oxidation peak at 1.11 V/SCE, those values being classical for most carbo-benzene derivatives. Calculated NICS values (NICS(1)=−12.5±0.2 ppm) also indicate that the aromatic nature of the C18 rings is not markedly affected by the dialkynylbutatriene (DAB) connector between them.
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Origine : Publication financée par une institution
Licence : CC BY - Paternité

Dates et versions

hal-04532883 , version 1 (04-04-2024)

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Paternité

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Chongwei Zhu, Alix Sournia-Saquet, Valérie Maraval, Christian Bijani, Xiuling X Cui, et al.. From Stilbenes to carbo‐Stilbenes: an Encouraging Prospect. Chemistry - A European Journal, In press, ⟨10.1002/chem.202400451⟩. ⟨hal-04532883⟩
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