Synthesis And Properties Of Two-Photon Fluorescent Probes Based On Fluorene Structure

With the continuous development of life science and social medical level,people's demand for detecting and monitoring bioactive substances related to cell life activities is also increasing.Fluorescent probe has many advantages in detection.The detection effect of fluorescent probe is often intuitive and visible,the operation is convenient and fast,the object to be measured has specific selectivity,fast and efficient response.Based on the general advantages of fluorescent probes,two-photon fluorescent probes have the characteristics of two-photon absorption.The two-photon fluorescence probe has good penetration.They can be applied to deep-seated imaging with little damage to cells.When applied to the detection of substances in cells or organisms,they have natural advantages and are widely used in biological imaging.The steady-state maintenance of various trace elements in human body is closely related to people's health.When the concentration of trace elements deviates from the normal concentration range,it often leads to the occurrence of many diseases.Among them,copper ion plays a key role in many enzyme functions.Excessive accumulation of Cu²⁺in brain tissue will cause neurotoxicity,while insufficient intake of Cu²⁺will lead to metabolic disorder of nervous system and brain function disorder.As a result,developing fluorescent probes that capable of detecting Cu²⁺in biological cells is necessary.At present,our research group has developed many two-photon fluorescence probes based on spirodifluorene structure.Spirodifluorene has a three-dimensional orthogonal structure in space,which can effectively reduce the fluorescence quenching caused by the aggregation effect of the probe.However,the two-photon fluorescence probes based on spirodifluorene structure generally have large relative molecular weight and are not easy to enter the cell when doing biological cell imaging.Therefore,fluorene structure similar to spirodifluorene structure is selected in this paper,which connects two methyl groups at 9,9',which not only has small relative molecular weight and ensures the three-dimensional orthogonal structure,but also has the conjugated structure of fluorene double bond triphenylamine with two-photon properties.It is planned to take this as the matrix to develop a two-photon fluorescence probe that can be used to detect copper ion and hydrogen sulfide.The main work is as follows:Part ?:starting from fluorene,a series of two-photon fluorescence probes SPF-TM1,SPF-TM2,SPF-TM3,SPF-TM4,SPF-TM5 and SPF-TM6 were designed and synthesized,and characterized.Part ?:the performance of probe SPF-TM1 is studied.It is found that probe SPF-TM1 is a ratio two-photon fluorescence probe that can be used for specific detection of Cu²⁺.With the addition of Cu²⁺,the fluorescence emission intensity at371 nm increased,while the fluorescence emission at 463 nm decreased and redshifted by 15 nm.Within a certain Cu²⁺concentration range,The intensity ratio of the two fluorescence emission peaks of the system has a linear relationship with the concentration of Cu²⁺in the system:Y=-9.874X+60.26885(Y is the ratio of fluorescence intensity at 463nm and 371nm,X is the concentration of Cu²⁺in the system).The detection limit is 139n M.Part ?:the performance of probe SPF-TM2 is studied.It is found that probe SPF-TM2 is a quenched two-photon fluorescence probe that can be used for specific detection of Cu²⁺.Within a certain Cu²⁺concentration range,the fluorescence intensity of the system has a linear relationship with Cu²⁺concentration:Y=-261.44127 X+2573.158(Y=fluorescence intensity of the system,X=Cu²⁺concentration),and the detection limit is 52n M.Part ?:the performance of probe SPF-TM3 is studied.It is found that probe SPF-TM3 is a brightened two-photon fluorescence probe that can be recognized by naked eye and used to detect H₂S.When the H₂S concentration in the system is within a certain range,the fluorescence intensity of the system has a linear relationship with the concentration of hydrogen sulfide in the system:Y=38.10357X-229.97797(Y=fluorescence intensity,X=concentration of sodium hydrosulfide in the system),and the detection limit is calculated to be 35n M.Part ?:the performance of probe SPF-TM4 used to detect the water content of1,4-dioxane was tested.Within a certain water content range,there is a linear relationship between the fluorescence intensity and water content of the system:Y=-986.7X+5073.6(Y=fluorescence intensity,X=concentration of sodium hydrosulfide in the system).The detection limit is 0.0158%.