Organosiloxane and Polyhedral Oligomeric Silsesquioxanes Compounds as Chemiluminescent Molecular Probes for Direct Monitoring Hydroxyl Radicals.

Despite the tremendous progress in the research of luminescent probes for reactive oxygen species (ROS), designing luminescent ROS probes with high sensitivity for the individual ROS is still retarded because of their high reactivity and the rapid and complex interconversion reactions among them. Herein, organosiloxane and polyhedral oligomeric silsesquioxanes (POSS) compounds are designed as a novel class of luminescent molecular probes to produce extraordinary chemiluminescence (CL) based on the specific electrophilic attack of •OH. No CL signal can be obtained by the other ROS and strong oxidants. AEAP-POSS formed by hydrolytical condensation of 3-(2-aminoethylamino)propyl]trimethoxysilane (AEAPTMS) is constructed to covalently link a dye molecular, perylene diimide derivative (PDI), and an intramolecular chemiluminescence resonance energy transfer (CRET) system is obtained to realize the red shift of CL wavelength and enhanced CL intensity. This probe based on CRET is applied to monitor inherent •OH in ambient particular matter (PM2.5 and PM10). Density functional theory (DFT), ion chromatograph, X-ray photoelectron spectroscopy (XPS), particle size analysis, and fluorescence spectrum (FL) are applied to study the CL mechanism. These studies discover that electronically carbonyl CH3CO• is the CL emitter, and the silicon-oxygen skeleton in the organosiloxane and POSS compounds plays the key role in undergoing chemiluminescence (CL) reaction.