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

Rhenium-Based Molecular Trap as an Evanescent Wave Infrared Chemical Sensing Medium for the Selective Determination of Amines in Air

An evanescent wave infrared chemical sensor was developed to selectively detect volatile amines with heterocyclic or phenyl ring. To achieve this goal, a rhenium-based metallacycle with a “molecular-trap” structure was designed and synthesized as host molecules to selectively trap amines with heterocyclic or phenyl ring through Re–amine and π–π interactions. To explore the trapping properties of the material, a synthesized Re-based molecular trap was treated on an IR sensing element, and wide varieties of volatile organic compounds (VOCs) were examined to establish the selectivity for detection of amines. Based on the observed IR intensities, the Re-based molecular trap favors interaction with amines as evidenced by the variation of absorption bands of the Re molecular trap. With extra π–π interaction force, molecules, such as pyridine and benzylamine, could be detected. After optimization of the parameters for IR sensing, a rapid response in the detection of pyridine was observed, and the linear ranges were generally up to 10 mg/L with a detection limit around 5.7 μg/L. In the presence of other VOCs, the recoveries in detection of pyridine were all close to 100%