Theoretical Study Of Two-photon Fluorescent Probe Based On Nile Red Derivatives With Controllable Fluorescence Wavelength And Water Solubility

Hypochloric acid(HOCl)plays a vital role in the natural defense system.But the abnormal level of HOCl can cause cell damage and human aging and various diseases.It is of great significance to develop new probes for detecting HOCl in biosystem non-destructively and non-invasively.The purpose of this work is to explore new chemical modification strategies of two-photon excitation fluorescence(TPEF)probes to improve poor water solubility and low efficiency in imaging application.Nil-OH-6 with double ring-fused alkyl amino groups at 9-site and one fused benzene at 2,3-site based on Nile Red derivatives leads to the two-photon absorption cross-section values as high as 243 GM and attains good quantum yield of 0.49.Besides,the modification of terminal groups with different azetidine-heterospirocycles or N,N-dialkyl fused amino groups to Nile Red can effectively improve the fluorescence efficiency as well as increase the solubility in some extent.This study simultaneously improves the fluorescence performance and solubility of the two-photon probes to provide reliable guidance and pavement for the subsequent synthesis of TPEF probes based on Nile Red.