Synthesis And Properties Of The Chemical Sensor Molecules Based On FRET Rhodamine B-Diarylethene

Diarylethenes show good photochromic characteristics with excellent thermal stability and remarkable fatigue resistance. Perfluorocyclopentenes have important scientific value and broad applications in the field of molecular switches. In recent years, the research on diarylethene molecular structure linked to certain functional groups has received much interest from scientiscs.In present study, we have designed and synthesized some fluorescence chemical sensor molecule based perfluorocyclopentene-rhodamine B to form FRET. Perfluorocyclopentenes are regarded as the matrix molecules linked rhodamine B through different junctional complex. Seven new diarylethene compounds based rhodamine B are synthesized, and their structures are characterized by NMR, IR, mass spectrum and elemental analysis. Diarylethenes showed excellent photochormism with alternating UV/Vis irradiation. Their unique multi-addressable switching characteristics induced by chemical and optical dual inputs stimulation were observed using UV and FL measurements.Protonated of diarylethenes with TFA resulted in good photochromism and notable fluorescence change via the FRET mechanism. It was found that the diarylethene bearing a rhodamine moicety linked wtih a benzhydrazide bridge was more sensitive, efficient, and reacted faster to protonation by TFA compared to the benzamide bridged derivative. Subsequent addition of triethanolamine resulted in disapperaracce of fluorescence of the compounds. Upon exposure to UV (297nm), their fluorescence intensity decreased dramatically under acidic conditions along with photochromism from open-ring isomer to closed-ring isomer. The fluorescence intensity gradually increased upon irradiation with visible light (λ>450nm).Diarylethene derivatives bearing a rhodamine B linked with a benzhydrazide bridge group were investigated. The results illustrated that the benzhydrazide bridged diarylethene was selective towards Cr(Ⅲ), Al(Ⅲ), and Ca(Ⅱ) with significant color and fluorescence change. After irradiation with UV light, the fluorescence was quenched to30%of its original intensity due to the formation of the diarylethene closed-ring and the occurrence of FRET. Subsequent irradiation with visible light regenerated the open-ring form of diarylethene and recovered the original emission spectrum.Solvent effect on fluorescent emission intensity of two diarylethene derivatives bearing a rhodamine B unit linked with a hydrazide bridge and a acidamide bridge in the presence of TFA, respectively, have been investigated. The results illustrated that the fluorescence change of the diarylethene derivatives were most obvious in methanol solution. The fluorescence intensity of the diarylethene derivatives barely changed in DMSO, hexane, and ethyl acetate solution.Fluorescence response of diarylethene derivatives bearing a rhodamine B unit linked with a hydrazide bridge to different ions was investigated. The results illustrated that the hydrazide bridged diarylethene derivatives were selective towards Cr(Ⅲ), and Al(Ⅲ) with significant color and fluorescence changes. After irradiation with UV light, the fluorescence was quenched to30%of its original intensity due to the formation of the diarylethene closed-ring and the occurrence of FRET. Subsequent irradiation with visible light regenerated the open-ring form of diarylethene and recovered the original emission spectrum.