title: Synthesis, photophysical, and two-photon absorption properties of elongated phosphane oxide and sulfide derivatives.
abstract: A series of rod-shaped and related three-branched push-pull derivatives containing phosphane oxide or phosphane sulfide (PO or PS)-as an electron-withdrawing group conjugated to electron-donating groups, such as amino or ether groups, with a conjugated rod consisting of arylene-vinylene or arylene-ethynylene building blocks-were prepared. These compounds were efficiently synthesized by a Grignard reaction followed by Sonogashira coupling. Their photophysical properties including absorption, emission, time-resolved fluorescence, and two-photon absorption (TPA) were investigated with special attention to structure-property relationships. These fluorophores show high fluorescence quantum yields and solvent-dependent experiments reveal that efficient intramolecular charge transfer occurs upon excitation, thereby leading to highly polar excited states, the polarity of which can be significantly enhanced by playing on the end groups and conjugated linker. Rod-shaped and related three-branched systems show similar fluorescence properties in agreement with excitation localization on one of the push-pull branches. By using stronger electron donors or replacing the arylene-ethynylene linkers with an arylene-vinylene one induces significant redshifts of both the low-energy one-photon absorption and TPA bands. Interestingly, a major enhancement in TPA responses is observed, whereas OPA intensities are only weakly affected. Similarly, phosphane oxide derivatives show similar OPA responses than the corresponding sulfides but their TPA responses are significantly larger. Finally, the electronic coupling between dipolar branches promoted by common PO or PS acceptor moieties induces either slight enhancement of the TPA responses or broadening of the TPA band in the near infrared (NIR) region. Such behavior markedly contrasts with triphenylamine-core-mediated coupling, which gives evidence for the different types of interactions between branches.
authors.affiliation: PPSM, ENS de Cachan, CNRS, UMR, UniverSud Paris, Cachan, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Alain-Rizzo
authors.forename: Delphine
authors.initials: D
authors.lastname: Drouin-Kucma
authors.forename: Cédric
authors.initials: C
authors.lastname: Rouxel
authors.forename: Issa
authors.initials: I
authors.lastname: Samb
authors.forename: Jérémy
authors.initials: J
authors.lastname: Bell
authors.forename: Patrick Y
authors.initials: PY
authors.lastname: Toullec
authors.forename: Véronique
authors.initials: V
authors.lastname: Michelet
authors.forename: Isabelle
authors.initials: I
authors.lastname: Leray
authors.forename: Mireille
authors.initials: M
authors.lastname: Blanchard-Desce
mesh_terms: D000042:Absorption; D010087:Oxides / Q000138:chemical synthesis / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D017785:Photons; D013440:Sulfides / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D010087:Oxides; D010720:Phosphines; D013440:Sulfides; C044646:phosphine