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Highly Substituted Azulene Dyes as Multifunctional NLO and Electron‐Transfer Compounds
Author(s) -
Lambert Christoph,
Nöll Gilbert,
Zabel Manfred,
Hampel Frank,
Schmälzlin Elmar,
Bräuchle Christoph,
Meerholz Klaus
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200304923
Subject(s) - azulene , intramolecular force , chemistry , photochemistry , monoclinic crystal system , crystallography , crystal structure , stereochemistry
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.