Lei Gao - Encapsulation of Phosphine-Terminated Rhenium(III) Chalcogenide Clusters in Silica Nanoparticles

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      Publication Details (including relevant citation   information):

      Chem. Mater, 2010, 22 (23), 6240-6245

      Abstract:

      Cationic phosphine-terminated rhenium(III) chalcogenide   clusters—[Re6Se8(Et3P)5I]I,   [Re6S8(Et3P)5Br]Br,   [Re6Se8(Bu3P)5I]I,   and   [Re6S8(Bu3P)5Br]Br—were   synthesized and encapsulated in silica nanospheres in a one-pot,   base-catalyzed hydrolysis in acetonitrile. The cluster-doped   silica nanoparticles have diameters of 10−20 nm, as observed by   transmission electron microscopy (TEM). The diameter is dependent   upon the volume of the solvent added to the system. Reactions   conducted in >10 mL of acetonitrile led to the isolation of   particles 200   nm in diameter. The absorption and emission properties of the   clusters were maintained upon encapsulation. The 1H   resonance of the alkyl groups was not observed in the   silica-cluster composites via nuclear magnetic resonance (NMR),   and the emission blue-shifts, indicating that the clusters reside   within the silica framework, rather than on the surface. Upon   irradiation by light (λ > 420 nm), both the clusters and their   silica composites can generate singlet oxygen, demonstrating the   oxygen permeability of silica. The smaller silica-cluster   composites are potential candidates for photodynamic therapy and   for other applications of singlet oxygen. The encapsulation is   ineffective for neutral and anionic clusters. Electrostatic   interaction between cationic clusters and the anionic,   deprotonated silanol groups is proposed to drive the   encapsulation.

      Address (URL): http://pubs.acs.org/doi/abs/10.1021/cm101609p