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

Visible-Light Activation of the Bimetallic Chromophore–Catalyst Dyad: Analysis of Transient Intermediates and Reactivity toward Organic Sulfides

In order to develop a new photocatalytic system, we designed a new redox-active module (<b>5</b>) to hold both a photosensitizer part, [Ru^II(terpy)­(bpy)­X]^<i>n</i>+ (where terpy = 2,2′:6′,2′′-terpyridine and bpy = 2,2′-bipyridine), and a popular Jacobsen catalytic part, salen–Mn­(III), covalently linked through a pyridine-based electron-relay moiety. On the basis of nanosecond laser flash photolysis studies, an intramolecular electron transfer mechanism from salen–Mn^III to photooxidized Ru^III chromophore yielding the catalytically active high-valent salen–Mn^IV species was proposed. To examine the reactivity of such photogenerated salen–Mn^IV, we employed organic sulfide as substrate. Detection of the formation of a Mn^III–phenoxyl radical and a sulfur radical cation during the course of reaction using time-resolved transient absorption spectroscopy confirms the electron transfer nature of the reaction. This is the first report for the electron transfer reaction of organic sulfide with the photochemically generated salen–Mn^IV catalytic center