Progress of Dicyanomethylene-4H-Pyran Derivatives in Biological Sensing Based on ICT Effect

Abstract

As one of the typical fluorescent cores, dicyanomethylene-4H-pyran (DCM) derivatives exhibit excellent photophysical and photochemical properties, such as large Stokes shift, excellent light stability, and tunable near-infrared (NIR) emission. The luminescence mechanism of DCM probes mainly depends on the intramolecular charge transfer (ICT). Hence, by regulating the ICT process, the probes can specifically act on the target molecule. Accordingly, a series of NIR DCM probes have been constructed to detect the ions, reactive oxygen species (ROS), and biological macromolecules in cells. However, there is no relevant review to summarize it at present. This minireview mainly summarizes the NIR DCM probes based on ICT effect and their applications in biosensors and biological imaging in recent years. This will be beneficial to innovatively construct new DCM probes and actively promote their application in the future.

Keywords: bioimaging; biosensor; dicyanomethylene-4H-pyran (DCM); intramolecular charge transfer; near-infrared probe.

FIGURE 1

Structure and mechanism of DCM-1∼9 for detection of different substances.

FIGURE 2

(A) Fluorescence emission spectral changes of DCM-1 with various concentrations of ONOO⁻ in solution. (B) Fluorescence emission spectra of DCM-2 upon gradual addition of OCl⁻ in EtOH: H₂O = 1:1 (v/v). (C) Fluorescence emission spectra of DCM-3 upon the addition of CN⁻. (D) Fluorescence spectra of DCM-4 with different concentrations of Cu²⁺ in PBS solution. (E) Time-dependent emission spectra of DCM-5 with F⁻ in aqueous solution. (F) Fluorescence spectra of DCM-6 in the presence of H₂O₂ with excitation at 560 nm. (G) Fluorescence spectra measurement of DCM-7 in the presence of different concentrations of H₂O₂. (H) Specific detection of cytochrome P450 reductase among various reductants with DCM-8. (I) Emission spectra of DCM-9 with TYR in aqueous solution.