Using Microsoft Excel solver, which is an add-in program to solve optimization problems, a pK distribution was estimated. The pK distribution shows the relation between the pK values and concentrations of acids in a sample solution and is applied to analyze a heterogeneous surface. A titration curve was obtained from titration of a citric acid solution with a sodium hydroxide solution. The theoretical equation of the titration curve was converted into a linear equation. The equation was fitted to experimental data by the linear programming method included in Excel solver. The pK distributions estimated by Excel solver and by a specially designed program applying the simplex method are almost equal. This indicates that Excel solver can not only be applied for excellent estimation of pK distribution, but also that all Excel users can easily carry out similar determinations.
2, 6-Bis(quinolinecarboxy)methylpyridine (P2Q) was synthesized as fluorescent chemosensors for metal ions. P2Q hardly shows fluorescence itself, but it showed strong fluorescence with the addition of zinc or cadmium ions (If, Zn > If, Cd). Therefore, the Ab initio molecular orbital calculations (Gaussian 98) using the time-dependent density functional method with 6-31+G(d) basis set were carried out for a quinoline chromophore of P2Q and its metal complexes to investigate the emission mechanisms. The results of the molecular orbital calculations suggest that the lowest luminescent state has changed from the nπ* to the ππ* by coordinating with a metal ion.
To develop a higher performance Li-ion rechargeable battery it is necessary to make clear the structures and mechanism of the occlusion / release process of Li/Li-ion to carbon materials as cathode materials. In order to determine the carbon materials that minimize energy loss by electronic movement, HOMO and LUMO energies were calculated for 48 kinds of carbon skeleton using the RHF/3-21G of the ab initio molecular orbital calculation program Q-Chem. It was found that the repeated structures of tetrabenzo[bc, ef, kl, no]coronene(TBC) satisfy the demand for orbital energies of Li/Li(+), and that TBC6 is the smallest skeleton for this purpose.