Second Sphere Energies

From Eq. (18), the potential energy ofinteraction Oinner of permanent p and induced dipoles h close to an ion may be written  

The work WA p to break up the superdipole structure in associated polar liquids is small compared with + p.Aa. We see that the repulsive interaction between the induced electronic dipole and the total dipole field along the displacement axis has disappeared, i.e., all repulsive energy terms for each tj.tj and q.q pair are included in their work of formation, and repulsive terms containing p.EPj2 only involve those between permanent dipoles, giving an important simplification. If 

The dipole field creating i along the ion displacement axis is a geometrical function of all permanent dipole p and induced dipole j terms for a system ofn dipoles  

The first water molecule model used here assumed for simplicity that the negative dipole charges are at 0.15 A from the oxygen atom center, in the H-O-H planey  

The potential energy of interaction of an ion with a single solvent permanent dipole in a spherical shell is given by  

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In this report, we will describe some of our studies aimed at (i) obtaining new inorganic photosensitizers by second-sphere modification of known ones, and (ii) assembling photosensitizer units with other molecular components in discrete, covalently bound supramolecular structures. Studies of type (i), besides their intrinsic interest, have some relevance to the problem of how the properties of a photosensitizer are modified by inclusion in a supramolecular structure. Systems of type (ii) would be useful to study the basic processes of intramolecular electron and energy transfer involved in the performance of molecular photochemical devices. 

A second sphere interaction may result in quenching of the CT excited states by energy transfer processes, leading to luminescence quenching, eg the MLC I Re bpy luminescence of Re1 monomeric and polymeric complexes is quenched by Cu11 species and the sacrificial electron donor 2,2, 2"-nitrilotriethanol (TEOA) [95]. 

Jacobsen GM, Yang JY, Twamley B, Wilson AD, Bullock RM, DuBois MR, DuBois DL (2008) Hydrogen production using cobalt-based molecular catalysts containing a proton relay in the second coordination sphere. Energy Environ Sci 1(1) 167-174. doi 10.1039/B805309J... 

Exciplexes and Second Sphere Interactions The concept of exdplex formation in inorganic systems has received considerable attention in recent years. Exciplexes can be observed when ground state complex formation is forbidden but the excited state complex has a shallow energy minimum that can radiatively decay to the ground state (Equation (6) and (7)). McMillin and co-workers postulated exdplex contributions to nonradiative relaxation of Cu phenanthroline... 

Rizkalla and Choppin (1991, 1994) have reviewed the hydration of lanthanide ions. They report that experimentally determined values (by electrophoresis and diffusion) for the hydrated radii of the lanthanides increase from La to Dy but i jparently level off for the heavier lanthanides (fig. 7). Replicate determinations by different authors place the uncertainty on these experimental values at 0.02-0.03 A. The apparent discontinuity near Tb is curious, but is paralleled by the heats and fiee energies of formation of the aquo cations. The similarity suggests that the observed trend represents a real chemical characteristic of the ions, perhaps related to the change in the inner-sphere coordination number or the balance of inner-sphere/second-sphere hydration. A simple analysis of the ions based on these hydrated radii indicates hydration numbers of 12-15 across the series (Lundqvist 1981). David and Fourest (1997) offer a more detailed interpretation that suggests a larger number of waters associated with the lanthanide cations. 

The fact that in this case the CO ligands on Re still experience a small, but non-negligible, frequency shift is clearly due to the second-sphere effect of Ru transmitted to Re through the bridging cyanide. Preliminary picosecond TRIR data [96] indicate that the energy transfer process in the binuclear... 

This is only one of the contributions to the total volume rate of energy dissipation a second term which arises from explicit consideration of the individual spheres must also be taken into account. This second effect can be shown to equal 1.5 [Pg.588]

For elimination of intramolecular energy losses, we have synthesized ligands with high hydrophobisity - perfluoro-P-diketones R -CO-CH -CO-R, (R = CgF j or CgF R = phenyl or a-thienyl), that without second ligand eliminate completely water molecules from the inner coordination sphere. These ligands we have used in analysis at determination of Sm, Eu, Nd, Yb microamounts in high-purity lanthanide and yttrium oxides. 

Second, using the fully relativistic version of the TB-LMTO-CPA method within the atomic sphere approximation (ASA) we have calculated the total energies for random alloys AiBi i at five concentrations, x — 0,0.25,0.5,0.75 and 1, and using the CW method modified for disordered alloys we have determined five interaction parameters Eq, D,V,T, and Q as before (superscript RA). Finally, the electronic structure of random alloys calculated by the TB-LMTO-CPA method served as an input of the GPM from which the pair interactions v(c) (superscript GPM) were determined. In order to eliminate the charge transfer effects in these calculations, the atomic radii were adjusted in such a way that atoms were charge neutral while preserving the total volume of the alloy. The quantity (c) used for comparisons is a sum of properly... 

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