The use of fluorescence in determining formation constants of complexes : Part II. Complexes which fluoresce

Four different methods for the calculation of the formation constants of fluorescing complexes are discussed. The methods were used to determine constants for the complexes of aluminum(III), gallium(III) and indium(III) with 8-quinolinol-5-sulfonate anion.     

Some theoretical considerations in analytical chemistry : The influence of absolute concentration on the parameters of redox titrimetry

Redox reactions are classified into symmetrical, homogeneous and inhomogeneous reactions. Reaction deficiencies when expressed as concentrations are dependent on absolute reactant concentrations, but have been proved to be independent of dilution when expressed as ratios in symmetrical and homogeneous reactions. An expression relating change of reaction deficiency with dilution for inhomogeneous reactions has been derived ; dilution of the reactants very rapidly decreases the reaction deficiency.Expressions for potentials in terms of concentration ratios have been derived for homogeneous and symmetrical reactions and prove to be independent of dilution. For inhomogeneous reactions the absolute potential falls on dilution, although the relative potential change, e.g., from the midpoint of a titration, increases asymptotically to a maximum.New derivations of the equivalence point potential and of an expression for the quantitativeness, for symmetrical and homogeneous reactions confirm the classical expressions and demonstrate their independence of dilution. For inhomogeneous reactions, methods of calculation of quantitativeness and equivalence point potentials through reaction deficiencies are proposed. For such reactions, the equivalence point potential rises sharply with dilution, giving titration curves of increasing steepness. The dependence of mid-point potentials and relative change of potential during titration upon dilution are also examined.     

Molecular orbital energy levels for the sulfate Ion

A series of semiempirical molecular orbital calculations for the SO₄ ^2? ion is described. These calculations show the effect on the order of the molecular orbital energy levels of a) using the Wolfsberg-Helmholz approximation, b) using the Cusachs approximation, c) variation of the proportionality constant, F, in the Wolfsberg-Helmholz approximation, d) inclusion of d-orbitals in the basis set, and e) variation of ζ_d when d-orbitals are included. It is found that the highest filled level is t ₁ for all the Wolfsberg-Helmholz calculations when d-orbitals are included and is 3t ₂ for all the other calculations.     

Polaronic origin of the isotope effect on the London penetration depth in high-temperature superconducting oxides

Direct measurements of the in-plane London penetration depth λ _L have recently been performed on high-temperature superconducting copper oxides by a new low-energy muon spin rotation technique. The results show that λ _L is isotope dependent, evidencing unconventional electron–phonon interactions as its source. The data are interpreted here in terms of polaronic effects on the single-particle energies, which leads to level shifts and exponential band narrowing. Good agreement with the experimental data is obtained.