Synthesis and antibacterial activity of the metabolites of 9-fluoro-6,7-dihydro-8-(4-hydroxy-1-piperidyl)-5-methyl-1-oxo-1H,5H- benzo[i,j]quinolizine-2-carboxylic acid (OPC-7251)

The metabolites of 9-fluoro-6,7-dihydro-8-(4-hydroxy-1-piperidyl)-5-methyl-1-oxo-1H,5H- benzo[i,j]quinolizine-2-carboxylic acid (OPC-7251) (1), which has a potent antibacterial activity against gram-positive bacteria, characteristically Propionibacterium acnes, were synthesized to confirm their structures and to examine their antibacterial activity. The structures of three major metabolites (2, 3a and 4) were identified by means of comparison with the synthetic compounds. The antibacterial activity of the metabolites (2, 3a and 4) was found to be lower than that of 1.     

Photoinduced electron transfer from polystyrene pendant tris(2,2′-bipyridyl)ruthenium (II) complex to methylviologen

The characteristics of the photoinduced electron transfer reaction from polystyrene pendant tris(2,2′-bipyridyl)ruthenium (II) complex [Ru(bpy)] to methylviologen (MV²⁺) were studied. The rate constant k₁ from the excited state of the complex, Ru(bpy), to MV²⁺ were determined for both the polymeric and monomeric complexes from the lifetime τ of Ru(bpy) and the quenching rate of Ru(bpy) by MV²⁺. The polymer pendant Ru(bpy) showed three kinds of τ components ranging from 7 to 474 ns, in contrast to the monomeric complex, which showed one component of 350 ns. The k₁ values for both complexes were almost the same, on the order of 10⁸ L/mol s. The photoinduced electron transfer from solid-phase Ru(bpy) to liquid-phase MV²⁺ was realized by utilizing the polymer complex, and the solid–liquid interphase reaction system is discussed.     

Two-step nitridation of photocatalytic TiO2 films by low energy ion irradiation

Nitridation of TiO₂ films is performed by the simultaneous irradiation of low-energy N₂⁺ and H₂⁺ ions under substrate-heating condition. Spectroscopic observations of the resultant films clarify the formation of nitrogen-substituted TiO₂ (TiO_2−xN_x) with large N fractions and the agglomeration of undesirable oxynitride species attributed to the deep states in the band gap. We find that the addition of a thin TiO₂ cap layer on the ion-irradiated films improves the nitrogen bonding structure and distribution near the surfaces, leading to a good photocatalytic performance even in the visible region.     

Minute displacement and strain analysis using lensless Fourier transformed holographic interferometry

An optical system for lensless Fourier transformed holographic interferometry is constructed to enable the measurement of minute displacements from nanometers to micrometers scale and to obtain corresponding strain distributions using a CCD camera with poor spatial resolution. Since a Fourier spectrum of an object beam is recorded on a hologram in this technique, the image reconstruction is easily performed with a single pass of 2-D fast Fourier transformation. Then, the map of the phase difference over the whole field is obtained by comparing two images before and after deformation. A suitable and effective unwrapping process is, however, inevitably required since the phase difference distribution is wrapped from −π to π in this technique. For phase unwrapping, the maximum spanning tree method is adopted here, which seeks a spanning tree that maximizes overall edge weights given by the cross amplitude. In-plane and out-of-plane displacements are obtained separately from the phase difference distributions at one's request. Moreover, in-plain strain is easily calculated from the in-plane displacement distribution.     

Electronic spectra and electronic structures of [2.2]paracyclophane and related compounds

The absorption spectra of [2.2]paracyclophane (PC), tetramethyl [2.2]paracyclophane (DD), and triple- and quadrupole-layered cyclophanes (DDD and DDDD) were measured with the n-heptane and 3-methylpentane solutions in the range of 25000–59000 cm^?1. The polarized absorption spectra of the [2.2]paracyclophane single crystal were measured in the range of 30000–50000 cm^?1 for the ab plane and 30000–37500 cm^?1 for the ac plane. Strong bands corresponding to the 180 nm band of benzene were newly observed at 53000, 49750, 49600, and 50000 cm^?1 for PC, DD, DDD, and DDDD, respectively.The electronic structures of PC, DD, DDD, and DDDD were studied semiempirically by considering the configuration interaction among the ground, locally excited and charge-transfer configurations.From the band positions, the absorption intensities, and the band polarization obtained experimentally and theoretically, we made the more reasonable and more reliable band assignments compared with those by the previous authors.     

Research on the pig liver esterase (PLE)-catalyzed kinetic resolution of half-esters derived from prochiral diesters

The pig liver esterase (PLE)-catalyzed kinetic resolution of half-esters derived from prochiral diesters is described. Generally, the PLE-catalyzed enantioselective hydrolysis of prochiral diesters affords the corresponding half-esters in high yield, because further hydrolysis of the half-esters does not typically occur. However, we found that some half-esters undergo PLE-catalyzed hydrolysis when they are gradually added to a PLE suspension in a potassium phosphate buffer at pH 8.0 via a syringe pump, leading to the kinetic resolution of the half-esters.     

Enantioselective Total Synthesis of (+)‐Ophiobolin A

The enantioselective total synthesis of (+)‐ophiobolin A is described. This total synthesis features the construction of the spiro CD ring of (+)‐ophiobolin A through a stereoselective intramolecular Hosomi–Sakurai cyclization reaction, the joining of the A ring to the CD ring by using a reaction reported by Utimoto, and the construction of the ophiobolin eight‐membered carbocyclic ring through ring‐closing metathesis (RCM), which was performed for the first time in this study. This successful RCM reaction required the use of a substrate that contained either a benzyloxy or a methoxymethoxy group at the C5 position and either an isopropenyl group or its hydroxylated form at the C6 position.     

Structure and dynamics of a complex of cellulose with EDA: insights into the action of amines on cellulose

The neutron structure of a complex of EDA with cellulose has been determined to reveal the location of hydrogen atoms involved in hydrogen-bonding. EDA disrupts the hydrogen-bonding pattern of naturally occurring cellulose by accepting a strong hydrogen-bond from the O6 hydroxymethyl group as the conformation of this group is rotated from tg to gt. The O3-H·O5 intrachain hydrogen-bond commonly found in cellulose allomorphs is observed to be disordered in the neutron structure, and quantum chemistry and molecular dynamics calculations show that O3 prefers to donate to EDA. The hydrogen-bonding arrangement is highly dynamic with bonds continually being formed and broken thus explaining the difficulty in locating all of the hydrogen atoms in the neutron scattering density maps. Comparison with other polysaccharide-amino complexes supports a common underlying mechanism for amine disruption of cellulose.