Aggregation-Induced Electrochemiluminescence and Nitric Oxide Recognition by Halogen Bonding with a Ruthenium(II) Complex

In this study, a new strategy for NO detection based on the aggregation-induced electrochemical luminescence (AIECL) of a ruthenium-based complex and the halogen bonding effect was developed. First, [Ru(phen)(2)(phen-Br-2)](2+) (phen : 1,10-phenanthroline, phen-Br-2 : 3,8-dibromo-1,10-phenanthroline) was synthesized and exhibited aggregation-induced emission (AIE) and AIECL properties in a poor solvent (H2O). [Ru(phen)(2)(phen-Br-2)](2+) exhibited greatly enhanced AIECL properties compared to its AIE intensity. When the volume fraction of water (f(w), v %) in the H2O-acetonitrile (MeCN) system was increased from 30 to 90 %, the photoluminescence and electrochemiluminescence (ECL) intensities were three- and 800-fold that of the pure MeCN system, respectively. Dynamic light scattering and scanning electron microscopy results indicated that [Ru(phen)(2)(phen-Br-2)](2+) aggregated into nanoparticles. AIECL is sensitive to NO because of its halogen bonding effect. The C-Br center dot center dot center dot N bond between [Ru(phen)(2)(phen-Br-2)](2+) and NO increased the distance of complex molecules, resulting in ECL quenching. A detection limit of 2 nM was obtained with 5 orders of magnitude linear range. The combination of the AIECL system and the halogen bond effect expands the theoretical research and applications in biomolecular detection, molecular sensors, and stages of medical diagnosis.

Automated summary

A new strategy for NO detection based on aggregation-induced electrochemical luminescence (AIECL) and halogen bonding effect was developed in this study. [Ru(phen)(2)(phen-Br-2)](2+) exhibited enhanced AIECL properties compared to its AIE intensity in a water-acetonitrile system. A detection limit of 2 nM was achieved with a linear range of 5 orders of magnitude. The combination of AIECL system and halogen bond effect expands the applications in biomolecular detection and medical diagnosis stages.