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Journals and Conferences
Upon light excitation MOF-5 behaves as a semiconductor and undergoes charge separation (electrons and holes) decaying in the microsecond time scale. The actual conduction band energy value was estimated to be 0.2 V versus NHE with a band gap of 3.4 eV. Photoinduced electron transfer processes to viologen generates the corresponding viologen radical cation,… (More)
Radical cations and dications of three bishydrazines belonging to the Class II mixed valence compounds have been generated, either spontaneously or by oxidation with AgSbF6, in two 1-butyl-3-methylimidazolium (4+) ionic liquids having BF4(-) and PF6(-) as counterions. The optical spectra of these intermediates have allowed evaluation of Marcus'… (More)
Laser flash photolysis of germanium-containing ITQ-17 zeolite (Ge/ITQ-17, a single polymorph of beta zeolite) at 266 nm generates a transient spectrum decaying in the sub-millisecond time scale that is compatible with the formation of two transient species. The shorter lived transient (tau approximately 45 micros under nitrogen) has been assigned to trapped… (More)
A -catenane consisting of a bipyridinium cyclophane and a dioxybenzene macrocyclic polyether has been encapsulated within the supercages of zeolite Y by ship-in-a-bottle synthesis; laser flash photolysis reveals that the charge-separated species decays in hundreds of microseconds in contrast to the few picoseconds previously reported for the same… (More)
A periodic mesoporous MCM-41 organosilica containing trans-1,2-bis(4-pyridyl)ethylene (t-BE) (350 m2 g-1; 0.28 cm3 g-1) incorporated in the silica walls undergoes photochemical isomerization to the cis configured bis(4-pyridyl)ethylene resulting in a dramatic area (473 m2 g-1) and pore volume (0.38 cm3 g-1) increase.
Transient absorption spectroscopy of graphene oxide (GO) and reduced graphene oxide (rGO) suspensions provides evidence for the photochemical generation of a charge-separated state on the microsecond timescale upon laser excitation. The lifetime and quantum yield of charge separation in suspended rGO were found to be higher than for GO. This could be… (More)
A series of (N, O)-co-doped graphenes with different N and O loadings are prepared by the pyrolysis of natural chitosan. When the percentage of dopant increases, the conduction-band potential and charge-separation quantum yield increase, whereas the charge-separation lifetime decreases.
In the context of gaining understanding on the origin of the visible-light photoresponse of TiO2 containing gold nanoparticles, the photocurrent spectra and photocatalytic H2 evolution of titania (P25) and Au-P25 were compared. Whereas no photocurrent was detected upon visible-light irradiation for either of the two photocatalysts, Au-P25 exhibited… (More)
Ionic liquids are suitable media which stabilize charged intermediates favoring those mechanisms that occur through charge separation. We have used ionic liquids to develop a photocatalytic system to perform the reduction of a carbonyl group to alcohol, thus mimicking the behavior of the reductase enzymes. The photochemical cycle is based on the well-known… (More)
Organogold compounds arising from the trapping of carbon-centered radicals by gold chlorides (AuCl, AuCl3, and HAuCl4) and colloidal gold have been characterized by different spectroscopic techniques. Laser flash photolysis has provided kinetic evidence of the occurrence of radical trapping in the microsecond time scale, while theoretical calculations give… (More)