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The fluorescence rise and decay times and UV absorption spectra of 1-methyl-4-amino-5H-[1]benzopyrano-[3,4-c]pyridin-5-one (1-MBPP), 2-methyl-4-amino-5H-[1]benzopyrano[3,4-c]pyridin-5-one (2-MBPP), and the 1-MBPP/acetic acid and 2-MBPP/acetic acid systems have been measured in hydrocarbon and hydroxylic solvents at room temperature and 77 K. From these data, a rapid formation of proton-transferred species (tautomers) was found to occur in an excited state for 1-MBPP (or 2-MBPP) hydrogen-bonded dimers in hydrocarbon at 77 K, and for 1-MBPP (or 2-MBPP) hydrogen-bonded complexes with acetic acid in hydrocarbon at room temperature and 77 K. The rise times of the tautomer fluorescence for the dimers and complexes were less than 65 ps. The observed fluorescence lifetimes of the 1-MBPP and 2-MBPP monomers agreed well with the lifetimes calculated using the integrated absorption intensity and fluorescence quantum yield.

The effect of thymosin against tumor progression was examined in mice immunosuppressed by cytostatics or X-ray irradiation. When pretreated with cytostatic agents, such as 5-fluorouracil (5-FU) or BCNU, or by X-ray, and then inoculated with P388 or L1210 leukemias, mice died rapidly within a few days. In these systems, thymosin a1 given concomitantly with the cytostatic agents or after X-irradiation prevented rapid death and extended survival, although the mice eventually died with leukemia like normal mice inoculated with cells of the same tumor. Rapid death in the 5-FU-treated mice was also prevented by adoptive transfer of spleen cells from the donor mice if these had been treated with 5-FU plus thymosin a1, but not if they had received 5-FU alone. However, the restorative activity of the donor spleen cells was abrogated by treatment with anti-asialo GM1, but not by treatment with anti-Thy 1 or anti-mouse Ig serum, suggesting that the effector cells in the spleen are NK cells. In fact, thymosin a1, when given concomitantly with 5-FU or after X-irradiation, maintained the NK activity of spleen, which was damaged by treatment with 5-FU or X-irradiation alone. The present study indicates that thymosin a1 exerts a preventive activity against progression of leukemias at least in part through an effect on NK cells or their progenitor cells.

By irradiation with a focused laser beam, p-nitroanisole and N-[2-(p-nitrophenoxy)ethyl] aniline (2) in acetonitrile were found to show new reactions yielding nitroso compounds different from the case of the defocused laser beam irradiation. The laser intensity dependence of the product yield shows that the new reaction of 2proceeds viaa biphotonic process. The quenching effects of oxygen and cis-1,3-pentadiene upon the reaction rate indicate that the intermediate state is an excited singlet state.

The triplet-triplet absorption spectra of [2.2]paracyclophane and related cyclophanes (naphthalenophane, pyrenophane, and anthracenophane) were measured. Cyclophanes in which two component subunits fully overlap, show new bands together with monomer-like bands. The electronic structures of triplet states of these cyclophanes were studied theoretically by the “molecules in molecule” method, special attention being paid to the correlations of the electronic structures of cyclophanes with those of corresponding monomers and also to the dependences of the charge transfer interaction upon the overlapping between the component subunits and upon the molecular size.

Two kinds of model compounds for a bichromophoric ester, 2-(1-pyrenyl)ethyl p-cyanobenzoate (P2CN), were synthesized: 1-substituted 2-(1-pyrenyl)ethyl p-cyanobenzoates (RP2CN, R = Me, Et, and Ph) as flexible model compounds and trans-2-(1-pyrenyl)cyclohexyl p-cyanobenzoate (cyclo-P2CN) as a rigid model compound. P2CNand all the model compounds had an intramolecular exciplex emission (φEX≈ 0.010) and efficient quenching of fluorescence from the locally excited pyrene part (φLE≈ 0.001). The decay lifetimes of the locally excited pyrene were 365 ps for P2CNand 66 ps for cyclo-P2CN, which were respectively identical with the risetime for the exciplex formation. The 1H NMR of both P2CNand RP2CNshowed the shifts of H2″ and H3″ of the p-cyanobenzoyl to the higher and H10′ of 1-pyrenyl signals to the lower magnetic field compared with those of the reference compounds, approaching towards those of cyclo-P2CN. NOE was observed between H10′ and H2″ of cyclo-P2CN, and, although very weak, between H2′ and H3″ of MeP2CN. In the solid state, P2CNadopts a folded conformation, which is roughly close to the gauche conformation, with the dihedral angle of 57.5° between p-cyanophenyl ring and pyrenyl ring based on X-ray crystallographic analysis on a leaflet monoclinic crystal, suggesting the exciplex formation from this conformation in P2CN.

The photochemical introduction of trifluoromethyl group with CF3Br in aromatic and heteroaromatic rings was investigated for 9 compounds. Naphthalene, anthracene, anisole, N,N-dimethylaniline, ferrocene, benzo[b]thiophene, isoquinoline, and N-methylpyrrole gave trifluoromethylated products in 6.5–100% yields. In one step from uracil, a pharmacologically important 5-trifluoromethyluracil can be synthesized by this method in 11% yield. Based on the mechanistic study carried out for the naphthalene–CF3Br–CH3CN system, the reaction is found to proceed via the electron transfer from an excited singlet state of naphthalene to CF3Br.

Photochromism of N-salicylideneanilines and related compounds was studied by measuring the electronic and vibrational spectra of the transient species. The rise time of the transient electronic spectra of the photochromic colored species was measured by picosecond time-resolved spectroscopy and was found to be dependent upon solvent viscosity. FT IR spectra showed that the photochromic colored species took the keto amine form. Picosecond kinetic analysis demonstrated that an intermediate existed in the transfer process from cis-keto amine to the photochromic species. These facts led us to the conclusion that the photochromic phenomenon of N-salicylideneanilines occurred through enol imine\oversethν→enol imine*→cis-keto amine*→the intermediate→trans-keto amine (photochromic species).

Triplet-triplet absorption, phosphorescence, and ESR spectra have been measured on the 1,3,5-tricyanobenzene complexes with toluene, mesitylene, durene, and hexamethylbenzene. Four triplet-triplet absorption bands were commonly observed in the wave number region of 10000–30000 cm-1for all the complexes. The observed phosphorescence and T-T absorption spectra could be understood systematically by considering the interaction among zero-order charge-transfer triplet states and zero-order locally (within the acceptor) excited triplet states. From an analysis of the zero-field splitting values obtained from the observed ESR spectra, the contribution of the zero-order charge-transfer triplet state to the lowest triplet state was determined to be 76,65,25, and 9% for the 1,3,5-tricyanobenzene complexes with hexamethylbenzene, durene, mesitylene, and toluene, respectively. From the consideration on the results obtained for various polycyanobenzene complexes, the phosphorescence lifetime was found to decrease remarkably for the complexes with the charge-transfer character higher than 50% in their lowest triplet states.

Photo-Smiles rearrangement reaction of N-[?-(p-nitrophenoxy)alkyl]aniline was studied by measuring the absorption spectra of transient species. Two intermediates Aand Bwere observed and were assigned to a solvated ion pair and the Meisenheimer complex, respectively. The reaction scheme, starting material?intramolecular charge transfer on excitation?A?B?final product, was derived from the relative yields and lifetimes of Aand Bas well as from the effects of solvent polarity, of triethylamine and oxygen, and of the alkyl chain length on each step of reaction.

Photochemistry of [2.2]paracyclophane in glassy solvents at 77 K was studied. With irradiation, a species in which two benzyl radicals are linked together with an ethylene bridge was produced. From the ESR study, the radicals were found to form the benzyl radical pair in harder solvents. The emission spectrum and the emission lifetime of the radical species showed remarkable dependence on the solvent viscosity. In harder solvents, a new broad emission was observed on the longer wavelength side of the structured emission of the benzyl radical. From the studies of the excitation spectrum and the emission lifetime, this broad band was concluded to be the intramolecular excimer fluorescence of the radical pair. The photo-reaction of [2.2]paracyclophane was found to be biphotonic, occurring from a higher triplet state excited viathe lowest triplet state.

The infrared spectra of most of the overtones and combination tones of methyl bromide have been obtained. In the perpendicular band, the rotational fine structures have been observed. The values of the Coriolis coupling constants obtained from the analysis of the rotational fine structures are consistent with those obtained from the analysis of the fundamentals. It has been seen that, if one takes 0.03 as the error of the observed values of the Coriolis coupling constants, one can use the observed values to calculate the force constants.Most of the vibrational anharmonic terms, xij, have been obtained, but they are tentative yet.The rotational correction terms, α1and α2have been estimated from the combination-bands analyses.

The infrared spectra of CH3X and CD3X (X=Cl, Br and I) have been observed with a high-resolution instrument in the region 500–3300 cm−1. The rotational fine structures of all the E-type fundamental bands have been resolved and analyzed, giving the Coriolis coupling constants, the rotational constants and the frequencies of the band origins. The uncertainties of the observed molecular constants have been discussed. On the basis of the observed data for the rotational constants and their changes by the excitation of vibration, the structures of methyl halide molecules have been determined.

The photo-Smiles rearrangement was studied for two homologues of N-[2-(4-nitrophenoxy)ethyl]aniline by laser photolysis, an importance being attached to the effect of the alkoxyl substituent on the reactive position. The nitro group enhances the substitution at the para position, but the alkoxyl group does not play a significant role in the photosubstitution of the molecules.

The mechanism of photodissociation of [2.2]paracyclophane in glassy solvent at 77 K was studied. It is concluded that the dissociation of the CH2–CH2bridge occurs from higher triplet states (Tn) viathe lowest triplet state as an intermediate. The efficiency of the reaction depends on the characters of Tnstates; high from the locally excited state, and low from the charge-transfer state.

A stable micro second harmonic generation (SHG) laser consisting of a diode- pumped Nd:YVO4laser doubled by KTiOPO4achieves 3 times higher storage density than usual on an erasable optical disk.