Aggregate of Alkoxy-Bridged Re(I)-Rectangles as a Probe for Photoluminescence Quenching

Abstract

Alkoxy-bridged rhenium(I) rectangles [{(CO)(3)Re(mu-OR)(2)Re(CO)(3)}(2)(mu-bpy)(2)] (1, R = C(4)H(9); 2, R = C(8)H(17); 3, R = C(12)H(25); bpy = 4,4'-bipyridine) comprising long alkyl chains form optically transparent aggregates and exhibit luminescence enhancement in the presence of water. The aggregation of Re(I)-rectangle was followed using a light-scattering technique. Presumably, the enhanced luminescence efficiency resulted from restriction of torsional molecular motion in the aggregates. In addition, the rate of bimolecular quenching of Re(I)-aggregates in the triplet excited state by various electron donors (amines) and acceptors (quinones) was efficient. These results indicate that the excited state of aggregated Re(I) surfactants with an electron acceptor and donor facilitate the electron-transfer quenching process after they became preassociated inside the Re(I)-aggregated species. These synthesized compounds may be useful fluorescent materials in optoelectronic applications.

MHD Unsteady Flow of a Williamson Nanofluid in a Vertical Porous Space With Oscillating Wall Temperature

“…Generally, the nanoparticles used in nanofluids are typically made of metals, oxides, carbides, or carbon nanotubes and the base fluids used are usually water, ethylene glycol and oil. Moreover, the study of nanofluid is of growing interest for the observation of enhanced thermal conductivity which may throw light on the urgent cooling problems in engineering, for instance, the cooling of integrated circuits and micro-electromechanical systems (See Lee et al, 1999, Manimaran et al, 2002Manimaran et al, 2003;Xuan and Li, 2003;Buongiorno, 2006;Thanasekaran, et al, 2007, Marga et al, 2005Kakac, Pramuanjaroenkij, 2009). Vajravelu et al (2011) presented the detailed analysis of convective heat transfer in the flow of viscous Agwater and Cu-water nanofluids over a stretching surface.…”

Supramolecular Arrangement of Molybdenum Carbonyl Metallosurfactants with CO-Releasing Properties

“…However, this unique example is an alkoxy Re(I) complex that does not have an additional polar head-group, therefore it can be considered a metallosurfactant with the polarity located around the metal atom. 16 Organometallic metallosurfactants based on metal carbonyls are attractive molecules because they can lead to singular supramolecular arrangements and, in addition, the presence of a metal carbonyl group makes it possible to use these compounds in different potential applications. As happens with conventional surfactants, which self-assemble in water, metallosurfactant molecules also form aggregated structures.…”

Neutral discrete metal–organic cyclic architectures: Opportunities for structural features and properties in confined spaces

“…Scheme 67. Self-assembly of neutral alkoxy-bridged rectangles 169-173 [273,274]. were obtained, respectively (Scheme 67) [273,274].…”

“…Self-assembly of neutral alkoxy-bridged rectangles 169-173 [273,274]. were obtained, respectively (Scheme 67) [273,274]. The more hydrophobic nature of rectangles containing a dodecyl group compared to those carrying an octyl and a butyl group enhanced their solubility in less polar solvents.…”