Energy polyoxometalates

Tributsch H (1982) Photoelectrochemical Energy Conversion Involving Transition Metal d-States and Intercalation of Layer Compounds. 49 127-175 Truter MR (1973) Structures of Organic Complexes with Alkali Metal Ions. 16 71-111 Tytko KH, Mehmke J, Kurad D (1999) Bond Length-Bond Valence Relationships, With Particular Reference to Polyoxometalate Chemistry. 93 1-64 Tytko KH (1999) A Bond Model for Polyoxometalate Ions Composed of M06 Octahedra (MOk Polyhedra with k > 4). 93 65-124... 

Photochromic dyes, 20 516 Photochromic glass silver in, 22 658, 686 as a solar energy material, 23 5 Photochromic lenses, 6 588, 601-602 Photochromic materials, 6 587-606 inorganic, 6 589-592 organic, 6 592-601 polyoxometalates, 6 591-592 silver halide-containing glasses, 6 589-590... 

It is known that molecules in photoexcited states are stronger oxidants and reductants than those in the ground states. The potentials of the excited states of polyoxometalates can be estimated by adding the energy of 0,0-transitions to the ground-state reduction potentials (257, 405). 

However, the emission from the excited states of polyoxometalates is usually so weak that it is difficult to determine the 0,0-transition energies exactly (257). 

Interest in polyoxometalate complexes of the rare earths has been driven to a large extent by their photophysical and photochemical properties. Table 1 lists several reviews. In general, photoexcitation into LMCT (O -> W, O -> Mo) bands results in intramolecular energy transfer to the rare earth with subsequent emission and luminescence. 

Figure 5.29 A schematic energy diagram of relaxation processes of the O— -M LMCT excitation energy in polyoxometaloeuropates lattices [80b]. (Reprinted with permission from T. Yamase, Photo- and electrochromism of polyoxometalates and related materials, Chemical Reviews, 98, no. 1, 307-326 (Figure 12), 1998. 1998 American Chemical Society.)...

Key Words Lewis acid adducts, Radical oxidations, Epoxidation, Hydrogen peroxide, Bond dissociation energy, Catalyst durability, Methyltrioxorhenium, Cross-bridged cyclam, Mn(IV), Late transition metal. Propylene oxide. Titanium silicalite (TS-1) catalyst, Ethylanthrahydroquinone/H2 process, Polyoxometallates, Mn(IV) catalyst. Hydrogen abstraction. Rebound mechanism, Isotopic label, t-BuOOH, Peroxide adduct. 2008 Elsevier B.v. 

FIGURE 21 Scheme of the energy transfer processes from the O — M Imct triplet states in both Anderson-typed polyoxometalates and polyoxometalloeuropates. Figure is redrawn... 

Eu-mixed polyoxometalate complexes. Figure 30A also shows the weak broad emission (peaking around 680 nm) of the O Mo Imct triplet states with approximately 1 /280 of the intensity of the total f-f emissions of both Eu and Tb the spectrum of which corresponds to the Ti Aig transition of [NH4]6[Mot024] 4FI20 (Table 6). Since the latter exhibits a bi-exponential decay lifetimes of 6 and 15 ps at 4.2 K (Yamase and Sugeta, 1993), the approximately exponential decay ( 0.23 ps) observed for the O —> Mo Imct triplet emission in 10 let us estimate the energy transfer rates from the O —> Mo Imct triplet states to Tb ( D4) and... 

The O M Imct triplet states are involved not only in energy transfer in polyoxometallolanthanoates but also in electron transfer for the photoredox reaction of the polyoxometalates with proton and electron donors (Yamase and Ohtaka, 1994 Yamase et al., 2003,2005,2006). This enabled us to propose a photochemical design of nano-ring Mo-blues by use of Ln in a novel bottom-up approach. Following the clarification of the primary steps of the photoredox reaction, nano-rings and nano-tubes based on Mo-blues have been successfully prepared by a photo-induced self-assembly reactions in solutions containing polyoxomolybdates, proton, electron donors, and Ln +. 

Polyoxometalate speciation in nonaqueous solvents has been investigated by electrospray ionization mass spectrometry (ESMS). This low energy ionization method minimizes fragmentation, e.g., (Bu°4N)2[Mo60i9] gives ion clusters with m/z values centered at 440 and 1,123 due to [MogOig] " and (Bu"4N)[Mo60i9] respectively. 

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