Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (07): 1453-1460.doi: 10.3866/PKU.WHXB201304244


Photophysical Properties and Photoinduced Electron Transfer Mechanism in a Near-IR Fluorescent Probe for Monitoring Peroxynitrite

ZHOU Dan-Hong, LI Miao-Miao, CUI Li-Li   

  1. Institute of Chemistry for Functionalized Materials, College of Chemistry and Chemical Engineering, Liaoning Normal University, Dalian 116029, Liaoning Province, P. R. China
  • Received:2013-03-18 Revised:2013-04-22 Published:2013-06-14
  • Contact: ZHOU Dan-Hong


A heptamethine cyanine dye containing an organoselenium functional group is a near-IR fluorescent probe that operates based on photoinduced electron transfer (PET). This probe can be used for highly sensitive and selective monitoring of peroxynitrite under physiological conditions. In this paper, the photophysical properties and PET mechanism of the probe molecule were investigated by time-dependent density functional theory (TD-DFT) calculations. The results indicated that the excitation in the fluorophore involves an electron transition from the highest occupied molecular orbital (HOMO) to the lowest unoccupied molecular orbital (LUMO). The HOMO level of the recognizer moiety increased in energy above that of the HOMO occupied with a single electron of the fluorophore, leading to transfer of one electron to the heptamethine cyanine moiety, which quenched the fluorescence emission. After the Se moiety was oxidized, the HOMO level of the recognizer moiety decreased in energy, the PET process was prevented, and the fluorescence emission was recovered. It was further proposed that the PET was contributed to by the p electron of the nitrogen atom in the aniline moiety of the probe. The PET efficiency is regulated by the oxidation and reduction events of the organoselenium moiety, resulting in“on-off”fluorescence emission.

Key words: Heptamethine cyanine dye, Organoselenium, Fluorescence sensor, Photoinduced electron transfer, Time-dependent density functional theory, Excited state