A CONVENIENT SYNTHESIS OF FUNCTIONALIZED DIBENZOTELLUROPHENES AND RELATED-COMPOUNDS VIA THE INTRAMOLECULAR TELLURO COUPLING REACTION - THE POSITIVE EFFECT OF HEAVY CHALCOGEN ATOMS ON THE MOLECULAR HYPERPOLARIZABILITY OF A CAPTODATIVE CONJUGATION SYSTEM

Nitro-containing dibenzotellurophenes and related compounds, which are otherwise laborious to obtain, were prepared by the reaction of 2,2'- diiodobiphenyl derivatives with an in situ prepared tellurium-copper s lurry. Partial reduction of 3,7-dinitrodibenzotellurophene using hydra zine hydrate/palladium on charcoal led to 3-amino-7-nitrodibenzotellur ophene, which was found to exhibit a relatively large third-order mole cular hyperpolarizability gamma (1.4 x 10(-31) esu) in the measurement of degenerated four-wave mixing (DFWM) as compared with 4-amino-4'-ni trobiphenyl and other previously reported compounds, confirming the po sitive effect of tellurium atom on the nonlinear optical property of a captodative conjugation system.