Construction and Application of a New Polarity-Sensitive Fluorescent Probe Based on the Excited-State Intramolecular Proton Transfer Mechanism

摘要

A new excited-state intramolecular proton transfer based near-infrared emission and polarity-sensitive fluorescent probe (E)-3-((E)-2-chloro-3-((E)-2-(3-ethyl-1,1-dimethyl-1H-benzo[e]indol-2(3H)-ylidene)ethylidene)cyclohex-1-en-1-yl)-1-(2-hydroxyphenyl)prop-2-en-1-one (M-NA) was developed. This probe consisted of benzomerocyanine unit and o-hydroxyacetophenone unit. In high-polar solvent, M-NA displayed higher fluorescence and longer emission wavelength. Theoretical calculations data showed that M-NA had larger emission oscillator strength and lower non-radiative decay in high polarity media, corresponding with the fluorescence character. Further experiments verified that M-NA possessed excellent selectivity and stability, and could further quantify the accurate polarity as well as the water content of binary mixed solvent.