Experimental and Theoretical Studies of Quadrupolar Oligothiophene-Cored Chromophores Containing Dimesitylboryl Moieties as π-Accepting End-Groups : Syntheses, Structures, Fluorescence, and One- and Two-Photon Absorption Article - Octobre 2014

Lei Ji, Robert Edkins, Laura Sewell, Andrew Beeby, Andrei S. Batsanov, Katharina Fucke, Martin Drafz, Judith A. K. Howard, Odile Moutounet, F. Ibersiene, Abdou Boucekkine, Eric Furet, Zhiqiang Liu, Jean-François Halet, Claudine Katan, Todd B. Marder

Lei Ji, Robert Edkins, Laura Sewell, Andrew Beeby, Andrei S. Batsanov, Katharina Fucke, Martin Drafz, Judith A. K. Howard, Odile Moutounet, F. Ibersiene, Abdou Boucekkine, Eric Furet, Zhiqiang Liu, Jean-François Halet, Claudine Katan, Todd B. Marder, « Experimental and Theoretical Studies of Quadrupolar Oligothiophene-Cored Chromophores Containing Dimesitylboryl Moieties as π-Accepting End-Groups : Syntheses, Structures, Fluorescence, and One- and Two-Photon Absorption  », Chemistry - A European Journal, octobre 2014, pp. 13618-13635. ISSN 0947-6539

Abstract

Quadrupolar oligothiophene chromophores composed of four to five thiophene rings with two terminal (E)-dimesitylborylvinyl groups (4 V-5 V), and five thiophene rings with two terminal aryldimesitylboryl groups (5 B), as well as an analogue of 5 V with a central EDOT ring (5 VE), have been synthesized via Pd-catalyzed cross-coupling reactions in high yields (66-89 %). Crystal structures of 4 V, 5 B, bithiophene 2 V, and five thiophene-derived intermediates are reported. Chromophores 4 V, 5 V, 5 B and 5 VE have photoluminescence quantum yields of 0.26-0.29, which are higher than those of the shorter analogues 1 V-3 V (0.01-0.20), and short fluorescence lifetimes (0.50-1.05 ns). Two-photon absorption (TPA) spectra have been measured for 2 V-5 V, 5 B and 5 VE in the range 750-920 nm. The measured TPA cross-sections for the series 2 V-5 V increase steadily with length up to a maximum of 1930 GM. We compare the TPA properties of 2 V-5 V with the related compounds 5 B and 5 VE, giving insight into the structure-property relationship for this class of chromophore. DFT and TD-DFT results, including calculated TPA spectra, complement the experimental findings and contribute to their interpretation. A comparison to other related thiophene and dimesitylboryl compounds indicates that our design strategy is promising for the synthesis of efficient dyes for two-photon-excited fluorescence applications.

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