title: Highly substituted azulene dyes as multifunctional NLO and electron-transfer compounds.
abstract: Two highly substituted azulene derivatives were synthesised by Pd-mediated dimerisation from the corresponding tolan species. One azulene derivative (2) has donor functionalities (dianisylaminophenyl and dianisylamino) in the 1-, 2-, 3- and 6-positions, while the other (1) has donors (dianisylaminophenyl) in the 2- and 6-positions and acceptors (nitrophenyl) in the 1- and 3-positions. Each azulene derivative shows strong bond length alternation in the solid state, determined by X-ray crystal analysis, and an intense CT band around 450-500 nm in its UV/Vis spectrum. The first-order hyperpolarisability of 1 and of 2 was measured by hyper-Rayleigh scattering and is about that of disperse red DR1. Both azulene derivatives show multiple oxidation processes. The intramolecular adiabatic ET behaviour of the mixed valence radical cations of 1 and of 2 was investigated by UV/Vis/NIR spectroelectrochemistry. The intervalence-CT band of 1(+) could be analysed by the Generalised Mulliken-Hush theory, which yields an electronic coupling V=1140 cm(-1) for the optically induced adiabatic hole transfer.
authors.affiliation: Institut für Organische Chemie Bayerische Julius-Maximilians-Universität Würzburg Am Hubland, 97074 Würzburg, Germany. lambert@chemie.uni-wuerzburg.de
authors.forename: Christoph
authors.initials: C
authors.lastname: Lambert
authors.forename: Gilbert
authors.initials: G
authors.lastname: Nöll
authors.forename: Manfred
authors.initials: M
authors.lastname: Zabel
authors.forename: Frank
authors.initials: F
authors.lastname: Hampel
authors.forename: Elmar
authors.initials: E
authors.lastname: Schmälzlin
authors.forename: Christoph
authors.initials: C
authors.lastname: Bräuchle
authors.forename: Klaus
authors.initials: K
authors.lastname: Meerholz