Excited states reactivity

Recall that the symmetry labels e and o refer to the symmetries of the orbitals under reflection through the one Cy plane that is preserved throughout the proposed disrotatory closing. Low-energy configurations (assuming one is interested in the thermal or low-lying photochemically excited-state reactivity of this system) for the reactant molecule and their overall space and spin symmetry are as follows ... 

Anthracenes, Excited State Reactivity and Molecular Topology Relationships in Chromophorically Substituted (Becker). 

In addition to the extensive information on the excited state cyclization reactivity summarized in Tables 1 -9, a wide body of reactivity data is available from studies of the direct photoaromatization process (D), the rate limiting step in such cases being the photocyclization process itself. This wealth of systematic and rather detailed excited state reactivity data is undoubtedly unique, providing numerous opportunities for theoretical studies of excited state reactivity some of which will be reviewed in Sect. VI. D. 

In order to build up dendrimers crqrable of exhibiting redox activity and light-induced functions, appropriate building blocks have to be used. In the last 20 years, extensive investigations carried out on the photochemical and electrochemical properties of transition metal compounds have shown that Ru(II) and Os(ll) complexes of aromatic M-heterocycles (Figure 1), e.g., Ru(bpy)j and Os(bpy)j (bpy = 2,2 -bipyridine), exhibit a unique combination of chemical stability, redox properties, excited state reactivity, luminescence, and excited state lifetime. Furthermore all these properties can be tuned within rather broad ranges by... 

E. Buncel and T. Durst, Eds., Comprehensive Carbanion Chemistry, Part C Ground and Excited State Reactivity, Elsevier, New York, 1987. 

In chloroform solvent, the platinum dithiolene complexes Pt(S2C2R2)2 are photooxidized between 300 and 350 nm, providing the complexes used are those for which the R groups result in redox potentials in the 0.1 to 0.5 V (vs SCE) range. The results are consistent with the reaction shown in equation (534).1849 Further work on this system identifies the fact that several excited states are probably photoreactive in this process,1850 and no definitive answer on the excited state reactivities is yet available. Very recently, however, highly structured solid-state emissions have been observed for Pt S2C2(CN)2 P(OR)3 2, and this data may help resolve some of these questions.1851... 

EXCITED STATE REACTIVITY AND MOLECULAR TOPOLOGY RELATIONSHIPS IN CHROMOPHORICALLY SUBSTITUTED ANTHRACENES... 

At the same time, uranyl reactivity has been studied by TRES without any reference to the theoretical results mentioned above for the lanthanides, as it was more or less clearly assumed that the uranyl excited-state reactivity is negligible (Geipel et al., 1996 Lopez and Birch,... 

The third chapter focuses on the modelization of solvent effects on ground state chemical reactivity and excited state reactive and non-reactive processes. 

Among quadruply-bridged platinum dimers, the pyrophosphite (POP) and methylenebisphosphite (PCP)-bridged species, which are the most widely studied [6][84][123-125], exhibit a strong red luminescence at 77 K [126], The substitution of X by Y in Pt2 [X2 species is markedly accelerated by light, and the conversion to Pt2 andX2 is photoinduced [127][128]. The excited-state reactivities of these species could be usefully compared with those of 17-electron monomers and other trapped diradical species. 

The convenient entry to arylmethyl radicals via homolytic photodissociation of the corresponding halomethylaryl precursors has been used to study the ground and excited state reactivities of -substituted benzyl radicals with 02172,173 and the excited state properties and reactivities of a series of arylmethyl radicals174,175. 

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