Cationic pi-electron systems with high quadratic hyperpolarisability

Citation
C. Lambert et al., Cationic pi-electron systems with high quadratic hyperpolarisability, J CHEM S P2, (6), 2001, pp. 964-974
Citations number
82
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
ISSN journal
1472-779X → ACNP
Issue
6
Year of publication
2001
Pages
964 - 974
Database
ISI
SICI code
1472-779X(2001):6<964:CPSWHQ>2.0.ZU;2-A
Abstract
Cationic NLO-chromophores based on tolane pi -systems in which conventional electron donors are combined with ionic pyridinio or triorganoammonio and -phosphonio substituents, respectively, perform much better than convention al donor/acceptor-substituted (D/A-substituted) tolanes concerning their hy perpolarisability-transparency trade-off. This effect occurs because ionic acceptors do not enlarge the pi -system in contrast to conventional accepto rs. The same holds true for benzene-type chromophores. Despite their differ ent electronic nature, the extrapolated maximal high-energy absorption of t he ionic chromophore series as well as of the conventional donor/acceptor-t olanes coincide at the absorption energy of unsubstituted tolane. This prov es that the maximal blue transparency of a given series of substituted chro mophores is governed by the absorption maximum of the unsubstituted parent chromophore. In this way chromophores have been designed with much higher q uadratic hyperpolarisability than e.g. p-nitroaniline at about the same abs orption wavelength. By applying the same concept, a two- and a three-dimens ional highly efficient octupolar NLO-chromophore assembly has also been syn thesised.