Highly substituted azulene dyes as multifunctional NLO and electron-transfer compounds.
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.
Lambert
Christoph
C
Institut für Organische Chemie Bayerische Julius-Maximilians-Universität Würzburg Am Hubland, 97074 Würzburg, Germany. lambert@chemie.uni-wuerzburg.de
Nöll
Gilbert
G
Zabel
Manfred
M
Hampel
Frank
F
Schmälzlin
Elmar
E
Bräuchle
Christoph
C
Meerholz
Klaus
K