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Single crystal of a series of (Z,E,Z)-1,6-diphenylhexa-1,3,5-triene 4,4'-dicarboxylic acid dialkyl esters that were prepared and their crystal structures and photoisomerization behaviors that were systematically investigated is described. The conformational flexibility of the alkyl chains made the large change in the trienegeometry in the lattice possible, leading to the enhancement of the photoreactivity in the crystalline state.

(Super 1)H and (super 13)C NMR studies have proved interactions between a thicarbonyl group and a pyridinium nucleus, and between a carbonyl group and a pyridinium nucleus. The experimental results suggested the existence of attractive (C=S)...Py(super +) and (C=O)...(Py(super +) interactions in solution and in crystal.

The interaction energy calculation of the thiophene dimmer is presented by using very large basis sets near saturation. The estimation of MP2 and CCSD(T) level interaction energies at the basis set limit are described by using model chemistry.

Research is presented concerning the use of density functional theory calculations to investigate the intermolecular interaction energy of the water-crownophane complex. The binding energy of the water is discussed.

Interactions between the pi face of benzene and ammonia are reported as a model of NH/pi interaction.

High-level ab initio calculations were used to evaluate the CH/varPi interaction of model systems and benzene.

The role of neutral species and metal coordination in the enzymatic cleavage of RNA have been investigated. The results showed that the cleavage occurs via a cyclic pentacoordinate oxyphosphane intermediate/transition state. The metal coordination produces an electrostatic field that allows in-line attack and departure process. This also prevents pseudorotations for the positional exchanges of ligands of pentacoordinate oxyphosphorane intermediate/transition state.

Studies of oxyphosphoranes such as neutral pentahydroxyphosphorane, dianionic trihydroxyphosphorane and trimethoxyphosphorane suggest that conformation of the P-O3 bond and its effect on reactivity are in accord with stereoelectronic effect-based predictions. The 'n-sigma asterisk interaction' is not crucial for the stereoelectronic control of the oxyphosphorane system.

The study explains the origin of attraction, magnitude and directionality of interaction energies in various benzene complexes having different pyridinium cations. The attraction between the benzene-pyridine complexes is found to be a result of the dispersion [pi]-[pi] interaction in the pyridine complex.

The isolation and X-ray structural characterization of two 16 pi electron octaethyl- and octaisobutyl-tetraphenylporphyrins are reported. The X-ray analysis of octaisobutyl-tetraphenylporphyrins showed a very similar distorted nonplanar structure to that of octaethyl, but in this case, H2O was found in the center of the core instead of CH2Cl2.