Research On Water Solubility Improvement And Performance Of Two-photon Fluorescent Probes Based On Spirobifluorene Structure

Fluorescence based sensors and imaging agents have been routinely used in biology,physiology,and pharmacology,and selective detection of biological or important substances in the environment has been developed for about 150 years.The use of fluorescent probes has revolutionized our understanding of a range of physiological or pathological processes and provides an effective sensing signal for the detection of harmful species that may be released into the environment（liquid or gas）.Although significant progress has been made in this exciting area,a number of challenges remain,including water solubility,applicability,selectivity and sensitivity.Since two-photon absorption is long wave excitation and short wave emission,it can effectively reduce the damage to cells,and its fluorescence emission occurs in a small area,so it can improve the spatial resolution and is widely used in biological imaging.Spirodifluorene molecule is composed of two vertical rings of fluorene.This structure avoids the accumulation of compounds and improves the quantum yield.The degree of conjugation can be adjusted through the rotation of the bonds;The 4 sites of2,9,2’and 9’of spirodifluorene are active sites,which are easy to modify other groups.This topic is to modify the amino group in the 9 site of the spirodifluorene,and then connect the amino group with the recognition function,and then modify the hydroxyl group in the triphenylamine to improve the solubility of the molecule,and finally synthesize the two-photon fluorescence probe with good performance.The main conclusions of this paper are as follows:1.SPF-A3,SPF-B3,SPF-C3 and SPF-D2,four two-photon fluorescence probes with detection performance were synthesized based on spirofluorene as parent.2.The properties of compound SPF-A3 were studied.Its solubility has been greatly improved and can be dissolved in water system.It is found that it is highly selective to SCN^-.When the excitation wavelength is 375nm,the fluorescence intensity can be increased by 2 times after the addition of SCN^-.Within a certain concentration range,with the increase of SCN^-concentration,there is a linear relationship with the fluorescence intensity:Y=114.7[SCN^-]+1.8×10³.The detection limit can be calculated as 130n M.3.The properties of compound SPF-B3 were studied.Its solubility has been greatly improved and can be dissolved in water system.It was found that it had a good detection effect on hydrazine hydrate.When the excitation wavelength is 375nm,the fluorescence intensity can be increased by 4 times by adding hydrazine hydrate.Within a certain concentration range,with the increase of hydrazine hydrate concentration,there is a linear relationship with the fluorescence intensity:Y=125.2[NH₂NH₂·H₂O]+750.The detection limit was 12n M which was one order of magnitude lower than that reported in the literature4.The properties of compound SPF-C2 were studied.It was found that the fluorescence intensity changed regularly with the change of water content in the test system.Within a certain range,the relationship between water content and fluorescence intensity is linear.In 1,4-dioxane,the linear equation is:Y=-1773X+4807,and the detection limit is 0.0088%.In THF,the linear equation is:Y=-1953X+3281,and the detection limit is 0.0077%.5.The properties of compound SPF-D2 were studied.Its water solubility has been greatly improved.It was found that it had specific selectivity for Ba²⁺.When the excitation wavelength is 375nm,the fluorescence is quenched immediately after adding Ba²⁺,and the detection effect is good.Within a certain concentration range,there is a linear relationship between the added Ba²⁺concentration and the fluorescence intensity:the equation Y=-130.1[Ba²⁺]+2996.6.the detection limit is 76n M.Moreover,the probe has good tolerance to acid and alkali,and is suitable for p H range of 6-10.