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チオフェン系アゾ色素は対応する置換アゾベンゼンより長波長側に吸収を示す。この現象（深色性）を明らかにする目的でベンゼン、チオフェン、フラン、ピロール、シクロペンタジエンおよびこれらのアザ置換体からなるアゾ化合物について量子化学計算をおこなった。まず、AM1、PM3、DFT計算によりそれぞれの安定配座を推定した。ついでチオフェン系アゾ化合物について硫黄原子の3d-AOを含めた場合と含めない場合のCNDO/S計算を行い、最長波長吸収帯に対する3d-AOの寄与は無視し得ることが確認された。さらに、CNDO/S法およびTD-DFT法によりスペクトル計算をおこなった。その結果、チオフェン系アゾ化合物が特異的に深色性を示すのではなく五員環系アゾ色素に共通した特性であることが示唆された。

We report here a novel method of visualization to record Born's probability densities in glass blocks by the use of a recently developed three-dimensional laser technique. Conventional visualization methods cannot simultaneously show all the characteristic features of an atomic orbital, whereas a real image in a glass block in the present study allows us to recognize both the shape of the orbital and its wave character, such as the existence of spherical, planar and/or conical nodes, at the same time. One can take this block in one's hands and observe it from an arbitrary direction, to gain clearly the whole image of probability density in it. To show a physical image of the behavior of an electron in an atom is profitable for the understanding of atomic orbitals. This method is the most appropriate to understand images of "the probability density".

Symmetry elements in various hydrogen atomic orbitals are summarized with respect to quantum numbers n, l and m. The results are useful to improve the efficiency of drawing the isosurfaces of these orbitals.

Relationships between the HOMO energy, the ν(C=O) stretching band, basicity(pKa), and σ(p) in phosphorus ylides have been studied. A linear relationship between the HOMO energies obtained by the AM1, HF/3-21G, and HF/6-31G methods and pKa was found. The same linear relationship was found between the HOMO energies obtained by these methods and σ(p)(indicated p-position). Thus, the HOMO energy can be adopted instead of pKa and σ(p) for choosing the ylide as the donor in organic reactions. In addition, a linear relationship between the ν (C=O) stretching bands obtained by these methods and the parameters described above was found. Hence, as for the electron donation of the ylide, it is noted that the HOMO energy can be used instead of pKa as a new method for showing the basicity of ylides. Furthermore, the ν(C=O) stretching bands obtained by these methods can be estimated by the HOMO energy obtained by the same methods.

An analyzer called “Q-chanG4” was developed with Visual Basic for photoluminescence quenching in a solid. This software can analyze the quenching mechanism in a solid matrix using emission decay curves and Stern-Volmer plots. Photoluminescence quenching of Tris(2,2’-bipyridine)ruthenium(II) in a polyethylene glycol solid by methylviologen was analyzed with Q-chanG4. The quenching mechanism was determined as a combination of a dynamic quenching and a static quenching involving multi-step equilibria and dynamic quenching. The dynamic quenching rate constant in the polyethylene glycol was as large as that in an aqueous solution, suggesting that the diffusion coefficient of molecules in the polyethylene glycol is almost the same as that in an aqueous solution in spite of the solid state.

A program, called PLEC-1, has been developed with Visual Basic to simulate and analyze the electrochemical measurement of a polymer-coated electrode with dispersed functional molecules. The program has two independent buffers for oxidant and reductant per one material and can concurrently treat seven materials and three chemical reactions of either first- or second-order. The user can not only experience virtual cyclic voltammetry and potential-step chronoamperometry but also analyze cyclic voltammograms by the Gauss-Newton method using the program. In PLEC-1, simultaneous partial differential equations are solved by the combination of Crank-Nicolson and iteration methods.