title: 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.
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.
authors.affiliation: Department of Chemistry, University of Durham, South Road, Durham, DH1 3LE (UK); Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg (Germany).
authors.forename: Lei
authors.initials: L
authors.lastname: Ji
authors.forename: Robert M
authors.initials: RM
authors.lastname: Edkins
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Sewell
authors.forename: Andrew
authors.initials: A
authors.lastname: Beeby
authors.forename: Andrei S
authors.initials: AS
authors.lastname: Batsanov
authors.forename: Katharina
authors.initials: K
authors.lastname: Fucke
authors.forename: Martin
authors.initials: M
authors.lastname: Drafz
authors.forename: Judith A K
authors.initials: JA
authors.lastname: Howard
authors.forename: Odile
authors.initials: O
authors.lastname: Moutounet
authors.forename: Fatima
authors.initials: F
authors.lastname: Ibersiene
authors.forename: Abdou
authors.initials: A
authors.lastname: Boucekkine
authors.forename: Eric
authors.initials: E
authors.lastname: Furet
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Liu
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Halet
authors.forename: Claudine
authors.initials: C
authors.lastname: Katan
authors.forename: Todd B
authors.initials: TB
authors.lastname: Marder
mesh_terms: D018360:Crystallography, X-Ray; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D011789:Quantum Theory; D013876:Thiophenes / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D013876:Thiophenes
keywords: boron; density functional calculations; luminescence; nonlinear optics; photophysics