Synthesis, Properties And Applications Of Novel ?-Extended Fluorescent Xanthene Probes

Xanthene dyes have many excellent photophysical properties such as large molar absorption coefficient,high fluorescence quantum yield,excellent photostability and good biocompatibility.These properties offer xanthene dyes a wide range of applications in the fields of optoelectronic device,fluorescent probe design and so on.Due to the visible absorption and fluorescence emission of conventional xanthene dyes(>600 nm),their bioapplications are limited.Therefore,the developing of long wavelength absorption and emissive xanthene dyes become one of the interesting themes.We present novel long wavelength xanthene dyes via building rectilinearly?-extended rhodamine chromophore;and derivatized a type of fluorescent probes which can detect methanol with high sensitivity and selectivity.In this thesis,we have carried out the following works:1.Using 1.4-dihydroxyanthraquinone as a starting material,novel xanthene fluorescent dye ZR with near-infrared absorption and fluorescence emission wavelengths has been synthesized.And then,functionalized pentacenequinone derivatives ZR1 and ZR2 as high selective sensors for methanol have been prepared from the acid-catalyzed rearrangement of ZR.Based on the methanol-induced keto-enol tautomerization of the pentacene-quinone moiety,ZR1 and ZR2 in ethanol exhibit specific selectivity toward methanol via the mechanism of intramolecular charge transfer(ICT)process,which lead to a naked-eye discernible dual-modal detection of methanol with very low detection limit of 0.033%and0.019%,respectively.They can be used for the mimic detection of methanol in liquor and the detection of methanol concentration in methanol gasolines.2.Via the intramolecular nucleophilic addition-elimination strategy,a near-infrared fluorescent dye ZRS with two xanthene rings linearly linked by a thiazine ring was designed and synthesized.The dye has a large conjugate coplanar characteristic.ZRS has near-infrared absorption and fluorescence emission properties.Its maximum absorption wavelength is at900 nm,and its maximum emission wavelength is at 775 nm.ZRS exhibits good biocompatibility,low cytotoxicity,and is lysosome-targetable.In addition,ZRS shows the high selectivity and high sensitivity for ClO~-.In summary,novel near-infrared xanthene fluorescent dyes ZR and ZRS have been designed and synthesized.ZRS exhibits good biocompatibility,low cytotoxicity,and is lysosome-targetable.Based on a acid-catalyzed rearrangement of ZR,functionalized pentacenequinone derivatives ZR1 and ZR2 as high selective sensors for methanol have been prepared.