Abstract

The effect of the quencher and length of the carbon chain on fluorescence quenching of N-alkenylcarbazoles with 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,4,7-trinitro-9-fluorenone (TNF) was investigated. During quenching the maxima of fluorescence for N-vinyl-, N-allyl-, N-pentenyl-, and N-hexenylcarbazole, similar to each other, are slightly shifted towards higher wavenumbers. Qeunching of the carbazoles is also similar. However, it differs considerably for TNF and TCNQ, the differences having both qualitative and quantitative character. The fluorescence intensity of the carbazoles is almost equal to zero at the carbazole:TCNQ concentration ratio 1:1 whereas in the case of TNF a large excess of the quencher is needed. The quenching factor, both for TCNQ and TNF, increases with increasing carbon chain length. The quenching factor for TCNQ is almost of an order of magnitude higher than for TNF. This is due to higher electron-acceptor properties of TCNQ, compared with TNF, since the quenching is associated with formation of charge-transfer complexes.

© 1984 Optical Society of America