Aqueous solutions, energy absorption

Upon combination of complexes 1 and 2 in an equimolar 0.025 mM aqueous solution, the absorption spectrum displayed features of both complexes. On the contrary, the emission spectrum of such mixture showed a maximum centered at 645 nm, which resembled only one of the complex 1, while the emission of complex 2 was not detected. The time-resolved emission analysis confirmed that the decay was only related to complex 1 above the CMC. These findings strongly indicate a full and efficient energy transfer process involving the iridium-based metallosurfactant 2, being quenched by the ruthenium-based amphiphilic complex 1 in a system that can be depicted as a mixed aggregate. 

Tab. 4.5 Singlet excitation energies of a small subset of psoralen compounds. Experimental data in aqueous solution given in parentheses [99]. Experimental absorption coefficients are denoted w=weak (<8000), i = intermediate (8000-15000), and s = strong (>15000).

A primary hydration number of 6 for Fe + in aqueous (or D2O) solution has been indicated by neutron diffraction with isotopic substitution (NDIS), XRD, 16,1017 EXAFS, and for Fe " " by NDIS and EXAFS. Fe—O bond distances in aqueous solution have been determined, since 1984, for Fe(H20)/+ by EXAFS and neutron diffraction, for ternary Fe " "-aqua-anion species by XRD (in sulfate and in chloride media, and in bromide media ), for Fe(H20)g by neutron diffraction, and for ternary Fe -aqua-anion species. The NDIS studies hint at the second solvation shell in D2O solution high energy-resolution incoherent quasi-elastic neutron scattering (IQENS) can give some idea of the half-lives of water-protons in the secondary hydration shell of ions such as Fe aq. This is believed to be less than 5 X I0 s, whereas t>5x10 s for the binding time of protons in the primary hydration shell. X-Ray absorption spectroscopy (XAS—EXAFS and XANES) has been used... 

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