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Relationships between the HOMO energy and σ(p) in ylides 1-14 have been studied. Linear relationships between the HOMO energies obtained by HF/3-21G[*] and 6-31G*, BLYP/6-31G*, and B3LYP/6-31G* methods and the substituent constant (σ(p)) were found, respectively. Hence, for the electron donation of the ylide, it is noted that the HOMO energy can be used as a new parameter for predicting the basicity of SN ylides. By comparing the results obtained by these calculations, the best method is found to be B3LYP/6-31G*. The results of bond lengths and torsion angles obtained by DFT calculations correspond with that of X-ray structure determinations.

A leuco crystal violet analog, tris(4-N, N-dimethylaminophenyl)methanethiol (1) was synthesized and utilized to the γ rays detection system. Acetonitrile solution of leuco dye 1 showed significant absorbance change after γ irradiation of 1 Gy, and the change was more significant than those of tris(4-N, N-dimethylaminophenyl)methanol (2) and leuco crystal violet (3).

A novel phenoxazine color former, 3, 7-bis(N, N-diethylamino)-10-(2, 2, 2-trichloroethoxycarbonyl)phenoxazine (1), was synthesized. Acetonitrile solution of colorless 1 was observed to give blue cation 2a by γ irradiation of 10 Gy. Little absorbance changes were observed when the blue shade solution was kept for 6 d after γ irradiation. Compound 1 showed excellent sensitivity to γ rays and the resulting cation 2a was stable enough to provide a candidate for a novel dosimetry system.

5, 8-Diphenyl-5, 8-dihydroanthra[1, 9-bc:4, 10-b′c′]diquinoline (ADQ, 3) and its endoperoxide (ADQepo, 4) were photochromic compounds with high heat stability. By heating above 100°C, colorless ADQepo (4) was slowly converted to green ADQ (3) in toluene. Reaction of ADQepo with some protic acid gave ADQ (3) at room temperature. The mechanism of this reaction was proposed based on the measurement of electronic spectrum.

The sensitivities to γ rays were investigated for photo acid generators: N-sulfonyloxy phthalimide 2, N-sulfonyloxy succinimide 3, N-sulfonyloxy 1, 8-naphthalimide 4, N-tosyloxy 5-norbomene-2, 3-dicarboximide 5, triphenylsulfonium trifluoromethane-sulfonate 6, diphenyliodonium chloride 7 and chloroform 8. The acid generation efficiency was monitored by the use of acid sensitive dye, fluoran dye 1a. The efficiency for γ irradiation decreased in the order 7>2>6>5>3>4. In the case of 8, decomposition of 1a was accompanied. 7 and 8 were of no practical use because volatile hydrogen chloride was generated. The others (2-6) generate methanesulfonic acid, p-toluenesulfonic acid or trifluoromethanesulfonic acid which are not so volatile acid as hydrogen chloride. N-sulfonyloxy imide compounds (2-5) have an advantage for practical use as dosimeter because these reagents dissolve in either polar or nonpolar solvent.

Reaction of fluoran dyes 1a-1f with hydrochloric acid was investigated. Hydrochloric acid was added to the fluoran solution ([1a-1f]=1.0x10-4mol dm-3) in organic solvents, and absorbance of formed colored species 2a-2f was measured by UV-Vis Spectrometer. The increment of the electron donation ability of substituent X at 3-position of 1 resulted in the increase of the formation of 2. When the chloroform solution of the most sensitive compound 1a was irradiated with γ rays, the solution turned red even at dose of 1 Gy. In order to investigate the effect of acid generators, 1b was irradiated with γ rays. Tosyl chloride 4 showed the possibility as an applicant for dosimetry in place of diphenyliodonium chloride 5.

Applying the procedure of precise Pariser-Parr-Pople molecular orbital (PPP MO) calculations, in which a novel two center electron repulsion integral new-γ was used and spectrochemical softness parameter in the new-γ was evaluated based on the spectroactive aromatic sextet resonance system (ASRS) of a molecule, the wavelengths of the p-band of acenes and their higher analogues were predicted. The relationship between the annellation and the shift of the wavelength of the p-band was revealed. The guideline to design PAHs which possess the long absorption wavelengths was proposed.

The applicability of semi-empirical PPP and INDO/S molecular orbital calculations For indoanilines (3) was investigated under three structural points of view: syn/anti isomerization, resonance canonical structures, and non-planarity of the molecule.