The Synthesis,performances And Application Of Fluorane-based Dyes

In recent years,fluoran organic dyes have been widely used in thermosensitive materials and fluorescence analysis due to their high molar absorption coefficient and sensitivity,large color density,good stability and wide chromatographic range.However,the development of heat-and pressure-sensitive materials started late in China.At the same time,the development of traditional organic dyes with largeπ-conjugated system（pyrene,perylene,xanthene,coumarin,etc.）was hindered to some extent by the aggregation-caused quenching（ACQ）effect during aggregation.In 2001,the concept of“aggregation-induced emission（AIE）effect”opened up a new research direction for the development of this type of dyes.These dyes play a critical role in many fields such as biological imaging,drug diagnosis and delivery,and organic optoelectronic materials.In addition,rhodamine dyes in fluoran family have been used as laser dyes,fluorescence standards and fluorescence sensors due to their excellent photostability and photophysical properties,but small Stokes shifts（<30nm）and short absorption and emission wavelengths seriously hinder their further application in cell imaging.In this paper,we synthesized fluoran dyes with AIE effect and viscosity response,respectively,and applied them to thermosensitive materials and biosensors.The main contents are as follows:（1）Three thermosensitive materials（fluo-AIE-gen 1、2、3）with AIE properties were synthesized by introducing tetrastyrene units with AIE effect into the parent structure of xanthene.The spectral and thermal properties of these dyes were investigated in detail.They exhibit excellent AIE effect in both solution and solid state,and have good repeatability,color rendering and environmental stability.Furthermore,they can be used in thermosensitive materials and color thin films.（2）A single-prime rhodamine dye was synthesized by using traditional Friedel-Crafts acylation reaction,which was used as a mitochondria-targetable and viscosity-sensitive sensor for the first time.The absorption（618 nm,H₂O）and emission wavelength（672 nm,H₂O）of sensor 1 are long and the Stokes shift reaches54 nm.It shows good membrane permeability and low dependence on p H.The sensor is sensitive to environmental change in viscosity and has been successfully used to detect viscosity in mitochondria in the living cell.