Arene ruthenium complexes possessing beta-amido phosphonate side chains participate in intramolecular spirocyclization reactions to deliver stable cyclohexadienyl ruthenium adducts. Spirocyclization is accomplished via a tandem two-step sequence that involves stereoselective nucleophilic aromatic addition to the ipso position of the coordinated arene, followed by intermolecular Horner-Wadsworth-Emmons olefination. The resulting eta5-cyclohexadienyl complexes can then be diastereoselectively converted to metal-free azaspiro[4.5]decane derivatives upon oxidative demetalation in the presence of suitable nucleophiles. An asymmetric spirocyclization was demonstrated through application of this procedure to a beta-amido phosphonate prepared from (S)-(-)-alpha-methyl benzylamine. The expected spirolactam product was obtained as a single enantiomer.
Dye-sensitized solar cells (DSSCs) based on mesoporous, high surface area nanocrystalline titania (TiO2) exhibiting up to 11% solar energy-conversion efficiencies are promising materials for cost-effective devices. Our objective here is to realize a cost-effective fabrication technique coupled with suitable device architecture of nanostructured DSSCs to achieve high photoconversion efficiencies. Atomic layer deposition (ALD) offers an attractive synthetic route for fabricating conformal photoanode coating materials on a nanoporous scaffold. Here, we used silica aerogels processed by doctor blading as structural scaffolds on transparent conducting oxide substrates, to promote subsequent conformal growth of thin films of TiO2 and aluminum-doped zinc oxide (AZO) by ALD. The resulting interdigitated architecture of the photoanodes can facilitate fast electron transfer. Dye sensitization of the photoanodes was accomplished using di-tetrabutylammonium cis-bis(isothiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) ("N719", Dyesol, B2 dye) and assembled into photocells using liquid electrolytes. Co-sensitization with a second dye was found to increase the photon absorption and cell efficiency.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.