Design And Synthesis Of NIR Fluorescent Probes Based On Novel Dyes

Fluorescence probe and fluorescence imaging have been regarded as the important tools to detect environmental ions and explored the biological structure and function.This analysis method has many advantages such as high sensitivity,good selectivity,short response time,easy operation and etc.Therefore,this technology received extensive attention.In recent years,though unremitting efforts,lots of fluorescent probes have been developed.However,there are many challenges in exploit new near-infrared(NIR)fluorescent probe.This paper has constructed a novel NIR fluorescent dye containing phenoxazine moiety,which could be modified as selective NIR fluorescent probes for metal ions.Main findings are as follows:(1)We synthesized novel NIR fluorescent dyes containing a hybride structure of phenoxazine and xanthene via an ingenious intramolecular S_NAr reaction.This type of dyes have some excellent features including simple synthetic method,low molecular weight,high quantum efficiency,low cytotoxicity,good photostability,and cell permeability.The redshift is about 80-100 nm compared with the rhodamine dyes.With the increase of pH value from 4to 8,the fluorescence intensity decrease and the change can be distinguished with naked eyes.In conclusion,these dyes have the potential to be used as pH probe.(2)To showcase the potential application of these dyes,we developed a NIR fluorescent probe C for copper ions though the modification of spirolactone platform by introducing a copper-responsive factor.Upon interaction with copper ions,the probe showed a unique turn-on response.(3)Based on the above results,we further expand the conjugation system of these NIR dyes.We designed and synthesized probe E.The probe E has near-infrared fluorescence emission itself and a structure of spiro lactam.The probe can interact with gold(?)selectively in solution and cell.The remarkable change in reacting with gold(?)is the change of fluorescence at different emission wavelengths,which can be used as a ratiometric fluorescence probe for gold(?).In conclusion,we have built a new type of NIR fluorescent dyes.Based on these dyes,we have prepared two NIR fluorescence probes for copper(?)and gold(?),respectively.Probes are cell permeable and can be used for copper(?)and gold(?)imaging,respectively,in living cells.