The Effect of Electron Donation and Intermolecular Interactions on Ultralong Phosphorescence Lifetime of 4-Carnoyl Phenylboronic Acids

Purely organic phosphors with persistent room-temperature phosphorescence (RTP) demonstrate promising potential applications in optoelectronic area, bioimaging, and chemical sensing. However, it is still a formidable challenge to further design new organic phosphors due to the unclear mechanism to produce ultralong phosphorescence lifetimes. This paper investigates the correlation between the ultralong phosphorescence lifetime and structure of a series of 4-carbonylphenylboronic acid derivatives in the crystal state. Experimental and calculation results reveal that the electron-donating effect of substituents makes the phosphorescence lifetime longer by not only weakening the vibration relaxation of the excited triplet state but also increasing the energy of T-1. Moreover, numerous intermolecular interactions for reducing nonradiative relaxation and the degree of the pi-pi stacking for stabilizing the triplet state are beneficial to the persistent RTP. The work is conducted to clarify the structure-property correlation of phosphorescent materials and design new persistent phosphors. Finally, an attempt is completed using phosphorescent materials to design two-dimensional or three-dimensional codes and anticounterfeiting applications.