title: Synthesis, characterization and optical properties of pi-conjugated systems incorporating closo-dodecaborate clusters: new potential candidates for two-photon absorption processes.
abstract: Non-centrosymmetric pi-conjugated systems incorporating closo-dodecaborate clusters, [NC-C6H4-C(H=N(H)-B12H11]-(2), [NC-C6H4-C(H)=C(H)-C(6)H(4)-C(H)=N(H)-B12H11]-(3), and [NC-C6H4-C(H)=C(H)-C6H4-C(H)=C(H)-C6H4-C(H)=N(H)-B12H11]-(4) have been synthesized by reaction of the monoamino derivative of B12, [B12H11NH3]-(1), with various arylaldehydes, R-C6H4-CHO. These Schiff base-like compounds were fully characterized by multinuclear NMR spectroscopy and mass spectrometry. In order to evaluate these boron rich pi-systems as potential materials for two-photon absorption (TPA) processes, UV linear absorption curves were recorded for 3 and 4, and comparatively studied with those of the boron-free pi-systems NC-C6H4-C(H)=N-CH3(5) and NC-C6H4-C(H)=C(H)-C6H4-C(H)=N-CH3(6). The donor effect of the boron cluster was evidenced by a shift to the lower energy of the absorption band in the spectra of systems incorporating B12. The two photon absorption (TPA) spectrum of compound , obtained by the up-conversion method, shows a resonance at 720 nm with a cross-section sigma(TPA) of 35 x 10(-50) cm(4) s photon(-1) molecule(-1). This value suggests the potential of B12 clusters to be used as new donor groups for the synthesis of non-linear materials.
authors.affiliation: Laboratoire des Multimatériaux et Interfaces, UMR CNRS 5615-Université Claude Bernard-Lyon 1, 43 Bd du 11 Novembre 1918, F-69622, Villeurbanne cedex, France.
authors.forename: R
authors.initials: R
authors.lastname: Bernard
authors.forename: D
authors.initials: D
authors.lastname: Cornu
authors.forename: P L
authors.initials: PL
authors.lastname: Baldeck
authors.forename: J
authors.initials: J
authors.lastname: Cáslavský
authors.forename: J-M
authors.initials: JM
authors.lastname: Létoffé
authors.forename: J-P
authors.initials: JP
authors.lastname: Scharff
authors.forename: P
authors.initials: P
authors.lastname: Miele