RESUMEN
The synthesis and photophysical characterization of two different series of electron donor-acceptor dyads containing Ru(II) and Os(II) bis-terpyridines (M(tpy)(2)(2+)) were prepared and studied in order to compare the oft-studied Ru(tpy)(2)(2+) chromophore with the less studied Os(tpy)(2)(2+) chromophore. The first series of dyads incorporates a benzoquinone (BQ) group as the electron acceptor, whereas the second contains a substituted pyromellitimide (PI) group as the electron acceptor. Steady-state emission experiments indicated efficient quenching of the 3MLCT emission of the electronically excited Os(II)-BQ complexes (7-8) compared to both model complexes (3-4) and the Os(II)-PI complex 10. Femtosecond pump-probe absorption experiments on 7-8 yielded ultrafast electron transfer rate constants (kET) of approximately 2.0 x 10(11) s(-1) (7) and 1.3 x 10(10) s(-1) (8) that were in good agreement with the low emission quantum yield results. Charge-recombination (kCR) in these complexes was also quite rapid, with rate constants of approximately 6.7 x 10(10) s(-1) (7) and 1.2 x 10(10) s(-1) (8). The analogous Ru(II) complexes underwent charge separation with rate constants of 7.6 x 10(10) s(-1) (5) and approximately 2.3 x 10(10) s(-1) (6), while charge recombination in these complexes occurred with rate constants of approximately 2.1 x 10(10) s(-1) (5) and approximately 5.3 x 10(10) s(-1) (6). Electron transfer in the pyromellitimide-containing complexes occurred only for Os(II)-PI (10), which exhibited significantly slower electron transfer (approximately 4.3 x 10(6) s(-1)) and charge recombination (approximately 7.7 x 10(6) s(-1)) rate constants. The nearly thermoneutral free energy of electron transfer and short excited state lifetime in the case of Ru(II)-PI (9) presumably prevents electron transfer in this compound.
Asunto(s)
Osmio/química , Compuestos de Piridinio/química , Rutenio/química , Benzoquinonas/química , Electroquímica , Transporte de Electrón , Colorantes Fluorescentes/química , Fotoquímica , Compuestos de Piridinio/síntesis química , Factores de TiempoRESUMEN
A novel tetrakis(terpyridinyl)porphyrin derivative and its Ru(II) complexes were efficiently synthesized using microwave enhanced synthesis and shown to possess photovoltaic properties. Transmission electron microscopy and selected area electron diffraction were used to investigate its nanowire self-assembly.
RESUMEN
The self-assembly of 3,5-bis(2,2':6',2''-terpyridin-4'-phen-3-yl)toluene with an equimolar amount of a Fe(II) salt afforded a high yield of an interlocked dinuclear tetracationic "molecular gear" that was confirmed by single crystal X-ray data.
RESUMEN
The self-assembly of Oxi-SWNTs, based on terpyridineCu(II) coordination, produces a thermally stable, neutral [(Oxi-SWNT)(tpyCu(II))m]n nanocomposite possessing notable luminscence properties; quantitative disassembly occurred by treatment with aqueous KCN.