Effects of Molecular Structure on Luminescent Properties of Betaine Dyes

Abstract

We compared spectral properties of Betaine-30 (B30) with other similar betaines or triphenylpyridine. They showed similar UV-absorption and shorter emission spectra in polymeric solids. The emission wavelength appeared to be red shifted with increasing polarity of the solvent or CT characteristics of dye molecule. Other dyes would be able to be used as B30 for a kind of polarity indicators, furthermore, B30 appeared to be most stable among them. We also compared their semiempirical M.O. calculation results. INDO/S calculations showed CT characteristics of their absorption bands in visible region.

Keywords:

• betaine-30
• E_T(30)
• INDO/S
• luminescence
• steric hindrance

Acknowledgments

This work was supported by the 21st century's COE program organized by the Ministry of Education, Culture, Sports, Science and Technology (MEXT). S.N. and Y.Y. thanks to MEXT for their financial support.

Notes

^*Data from Ref. 4.

^†Not observed.

^¶Not determined.

^‡Decomposition of the dye was observed in the emission spectrum.

^§Emission wavelength is not stable because of the weakness of the emission intensity or the effect of matrix absorption (at short λ_ex.).