Aggregation-Induced Emission Enhancement in Alkoxy-Bridged Binuclear Rhenium(I) Complexes: Application as Sensor for Explosives and Interaction with Microheterogeneous Media

The aggregation-induced emission enhancement (AIEE) characteristics of the two alkoxy-bridged binuclear Re­(I) complexes [{Re­(CO)₃(1,4-NVP)}₂(μ₂-OR)₂] (<b>1</b>, R = C₄H₉; <b>2</b>, C₁₀H₂₁) bearing a long alkyl chain with 4-(1-naphthylvinyl)­pyridine (1,4-NVP) ligand are illustrated. These complexes in CH₂Cl₂ (good solvent) are weakly luminescent, but their intensity increased enormously by almost 500 times by the addition of poor solvent (CH₃CN) due to aggregation. By tracking this process via UV–vis absorption and emission spectral and TEM techniques, the enhanced emission is attributed to the formation of nanoaggregates. The nanoaggregate of complex <b>2</b> is used as a sensor for nitroaromatic compounds. Furthermore, the study of the photophysical properties of these binuclear Re­(I) complexes in cationic, cetyltrimethylammonium bromide (CTAB), anionic, sodium dodecyl sulfate (SDS), and nonionic, <i>p-tert</i>-octylphenoxypolyoxyethanol (TritonX-100, TX-100), micelles as well as in CTAB–hexane–water and AOT–isooctane–water reverse micelles using steady-state and time-resolved spectroscopy and TEM analysis reveals that the nanoaggregates became small and compact size