A STUDY OF THE KINETICS OF INCLUSION OF HALONAPHTHALENES WITH ß-CYCLODEXTRIN VIA TIME CORRELATED PHOSPHORESCENCE

Abstract— The phosphorescence of 1-bromonaphthalene and 1-chloronaphthalene is readily observable in nitrogen purged aqueous solutions containing ß-cyclodextrin. Addition of acetonitrile increases both the phosphorescence intensity and lifetime. The quenching of halonaphthalene phosphorescence in aqueous solution by nitrite is substantially inhibited upon addition of ß-cyclodextrin, as a result of a guest-host complex. The rate constants for formation and dissociation of the l-bromonaphthalene/ß-cyclodextrin complex are evaluated from an analysis of the dependence of phosphorescence lifetimes on nitrite concentration.     

Simultaneous determination of YM-64227, a phosphodiesterase type 4 inhibitor, and its five metabolites in dog plasma by high-performance liquid chromatography with fluorescence detection

We developed and validated a reversed-phase high-performance liquid chromatographic method with fluorescence detection for the simultaneous determination of YM-64227 [4-cyclohexyl-1-ethyl-7-methylpyrido(2,3-d)pyrimidin-2-(1H)-one], a novel and selective phosphodiesterase type 4 inhibitor, and its fi ve hydroxylated metabolites in dog plasma. The plasma samples were extracted with tert-butyl methyl ether under alkali conditions. The analytes were well separated on a phenyl ethyl column (5 microm, 250 x 4.6 mm i.d.), opreating at 40 degrees C and using an acetonitrile-acetic acid gradient at a fl ow rate of 1.0 mL/min. The fluorescence signal was monitored at an excitation and emission wavelength of 330 and 400 nm, respectively. No interfering peak was observed at the retention time of YM-64227, its metabolites or the internal standard. The validated quantitation range of the method was 0.4-200 ng/mL for all analytes using 0.5 mL of the plasma sample. The recovery of analytes in the extraction process was more than 65.5%. The intra- and inter-assay precision was less than 5.1 and 12.6%, respectively, and the intra- and inter-assay accuracy ranged from -8.1 to 11.8% and -8.0 to 9.9%, respectively. Using this assay, the plasma concentration of YM-64227 and metabolites can be determined after the oral administration of YM-64227 to beagle dogs.     

Carrier doping effect into quasi-one-dimensional bromo-bridged Ni(III) complexes with strong electron-correlation by Cu(II) ions, [Ni1-xCux(chxn)2Br]Br2-x

This communication will describe the electron doping effect into Ni(III) complexes by Cu(II) ions, [Ni(1-x)Cu(x)(chxn)(2)Br]Br(2-x) (x = 0.038 and 0.101) by using an electrochemical oxidation method. A drastic increase of electrical conductivity as well as a new absorption band around 0.5 eV in single crystal reflectance spectra was observed by doping Cu(II) ions, indicating the electron doping was successfully made. An ESR result shows unpaired electrons locate in the d(x2-y2) orbitals of Cu(II) and have almost no interaction with those of other ions.     

Light-harvesting heptadecameric porphyrin assemblies

New porphyrin assemblies containing 17 porphyrin molecules are constructed by using free base TPP-type porphyrins having eight pyrazine moieties 1. Spectroscopic titration of dimeric [meso-tetrakis(2-carboxy-4-nonylphenyl)porphyrinato]zinc(II) 2 with these porphyrins shows that the processes of the formation of the heptadecameric porphyrin assemblies may be analyzed as eight independent equilibrium processes with an identical binding constant. All binding constants are larger than 5 x 107 M-1 which is the determinable upper limit of the present titration method. In all cases, the fluorescence spectrum of the 1:8 mixture of 1 and 2 consists of the major fluorescence of 1 and the minor one of 2.pyrazine complex even in the presence of the large excess of the antenna pigments. The observed spectra are well reconstructed by the form of faF1 + fbF2, where F1 and F2 are the fluorescence of 1 and the 2.pyrazine complex measured separately at the corresponding concentrations. Interestingly, the general trend that values of fa are nearly equal to those of r564 x (1 - fb) in all cases is found, where r564 is the absorption ratios of the 2.pyrazine moiety and the central free base porphyrin in the assemblies at 564 nm. The observation indicates the excitation of the central porphyrin is directly enhanced by the absorption of the antenna pigments even in such large scale assemblies. Thus, the antenna effect for 1 having largest r564 results in 77 times fluorescence enhancement of the central free base porphyrin. The systems also show interesting dependency of energy-transfer efficiencies on the topological arrangement of the antenna elements.     

Electrochemical and spectroelectrochemical studies on UO(2)(saloph)L (saloph = N,N'-disalicylidene-o-phenylenediaminate,L=dimethyl sulfoxide or N,N-dimethylformamide)

To examine properties of pentavalent uranium, U(V), we have carried out electrochemical and spectroelectrochemical studies on UO(2)(saloph)L [saloph = N,N'-disalicylidene-o-phenylenediaminate, L = dimethyl sulfoxide (DMSO) or N,N-dimethylformamide (DMF)]. The electrochemical reactions of UO(2)(saloph)L complexes in L were found to occur quasireversibly. The reduction processes of UO(2)(saloph)L complexes were followed spectroelectrochemically by using an optical transparent thin layer electrode cell. It was found that the absorption spectra measured at the applied potentials from 0 to -1.650 V versus ferrocene/ferrocenium ion redox couple (Fc/Fc(+)) for UO(2)(saloph)DMSO in DMSO have clear isosbestic points and that the evaluated electron stoichiometry equals 1.08. These results indicate that the reduction product of UO(2)(saloph)DMSO is [U(V)O(2)(saloph)DMSO](-), which is considerably stable in DMSO. Furthermore, it was clarified that the absorption spectrum of the [U(V)O(2)(saloph)DMSO](-) complex has a very small molar absorptivity in the visible region and characteristic absorption bands due to the 5f(1) orbital at around 750 and 900 nm. For UO(2)(saloph)DMF in DMF, the clear isosbestic points were not observed in the similar spectral changes. It is proposed that the UO(2)(saloph)DMF complex is reduced to [U(V)O(2)(saloph)DMF](-) accompanied by the dissociation of DMF as a successive reaction. The formal redox potentials of UO(2)(saloph)L in L (E(0), vs Fc/Fc(+)) for U(VI)/U(V) couple were determined to be -1.550 V for L = DMSO and -1.626 V for L = DMF.     

Construction of porphyrin-cyclodextrin self-assembly with molecular wedge

A new host porphyrin bearing four permethyl-beta-cyclodextrin moieties for multi-porphyrin assembly forms a unique 2 : 2 assembly with the tetra-anion of tetrakis(p-sulfonylphenyl)porphyrin (TPPS) in aqueous solution.     

Thermodynamic relationship between structural isomers of the thermochromic compound bis(N-Isopropyl-5,6-benzosalicylideneiminato)nickel(II)

A pair of structural isomers was isolated at room temperature for the thermochromic nickel complex bis( N-isopropyl-5,6-benzosalicylideneiminato)nickel(II); one is a diamagnetic green form with square-planar coordination geometry (G phase), and the other is a paramagnetic brown form with a tetrahedral geometry (B phase). However, a question as to which form is thermodynamically stable was left open. To solve this problem, thermal and magnetic properties of this complex were investigated by adiabatic heat capacity calorimetry in the 6-508 K temperature range and magnetic measurements in the 2-400 K region. In addition to the two forms previously reported, two metastable crystal forms (G' and B' phases) were found. The stable phase sequence was G phase, B phase, and then liquid upon heating. The supercooled B phase gave rise to a small phase transition with nonmagnetic origin at around 50 K. By rapidly cooling the liquid, a glassy liquid state was realized below approximately 290 K. The order of thermodynamic stability at 298.15 K was revealed to be the G, B, G', and then the B' phase. The entropy, enthalpy, and Gibbs energy differences between the B and the G phases at 298.15 K were S degrees (B) - S degrees (G) = 32.8 J K (-1) mol (-1), H degrees (B) - H degrees (G) = 16.0 kJ mol (-1), and G degrees (B) - G degrees (G) = 6.25 kJ mol (-1), respectively.     

High pressure Raman study of bromine and iodine: soft phonon in the incommensurate phase

A new phase of solid bromine was discovered at a pressure region above 80 GPa by Raman scattering experiments with a diamond anvil high-pressure cell. This phase was found to be the same as the iodine phase V with an incommensurate structure [Nature (London) 423, 971 (2003)] which appears between the molecular phase I and the monatomic phase II. In the incommensurate phases of both bromine and iodine, Raman active soft modes were clearly found in the low frequency region. The data suggest that the monoatomic phase II occurs above 30 and 115 GPa for iodine and bromine, respectively.     

Imaging of water distribution in thermally fractured granites by SPRITE

Water distribution in thermally fractured granite samples was visualized by using SPRITE sequences. Networks of intergranular fractures were observed in the coarse-grained Inada granite after heating at 873 K or above. On the other hand, bright spots were observed in the fine-grained Okazaki granite, which may be due to pore water in feldspar grains. D2O diffusion into samples saturated with H2O was also observed by 2D-projected SPRITE imaging.