Publications by authors named "Toru Okawara"
Growing evidence supports interactions between anxiety and cognitive function. The primary object of this study was to elucidate whether high-avoidance (HAA) and low-avoidance (LAA) strains of Hatano rats are suitable for the analysis of interactions between the formation of long-term memory and emotional reactivity. The learning/memory ability of Hatano rats and their Sprague-Dawley (SD) ancestors was evaluated using contextual fear conditioning, Y-maze, and Barnes maze tests from 8 weeks of age.
View Article and Find Full Text PDFAn aggregation-induced emission chromophore, vinylpyrrole, was prepared from a formylpyrrole derivative, Meldrum's acid, and 1,3-dimethylbarbituric acid. The optical properties of the chromophore both in the solution and solid states were investigated by UV-vis and fluorescence spectroscopy. Single crystal X-ray diffraction measurements revealed that the dimethylbarbituric acid adduct formed a J-aggregate in the solid and resulted in higher fluorescence quantum yield compared to the Meldrum's acid adduct.
View Article and Find Full Text PDFThe dihydrogenated porphycene cobalt(ii) complex was synthesized and electrochemical experiments were carried out. The one-electron reduction of the complex proceeded at the central metal to afford the Co(i) species; in contrast, for the non-hydrogenated porphycene cobalt(ii) complex, the one-electron reduction gave the ligand reduced radical anion species. The reactivity of the one-electron reduced species with alkyl halides showed clear differences between the complexes.
View Article and Find Full Text PDFA phosphorus(v) complex of porphycene [P(OEPc)(OMe)]PF (OEPc = 2,3,6,7,12,13,16,17-octaethylporphycenato dianion) has been synthesized and structurally characterized as the first porphycene derivative incorporating nonmetal elements in the macrocyclic cavity. An extremely low energy level of the LUMO is observed, which is rationalized by the low-lying π* orbital of the porphycene ring coupled with the insertion of the highly-inductive pentavalent phosphorus centre. The compound is luminescent in bright red with a quantum yield of 22.
View Article and Find Full Text PDFPhotoluminescent divinylbipyrroles were synthesized from 3,3',4,4'-tetraetyl-2,2'-bipyrrole-5,5'-dicarboxaldehyde and activated methylene compounds via aldol condensation. For mechanistic clarity, molecular structures of Meldrum's acid- and 1,3-dimethylbarbituric acid-derived divinylbipyrroles were determined by single-crystal X-ray diffraction. Photoluminescent properties of the synthesized divinylbipyrroles in dichloromethane were found to be dependent on the presence of electron withdrawing groups at the vinylic terminal.
View Article and Find Full Text PDFMetal-coordinated porphyrin and related compounds are important for developing molecular architectures that mimic enzymes. Porphycene, a structural isomer of porphyrin, has shown unique properties in semiartificial myoglobin. To explore its potential as a molecular building block, we studied the molecular assembly of nickel(II) tetra(n-propyl)porphycene (NiTPrPc), a metalloporphycene with introduced tetra n-propyl moieties, on the Au(111) electrode surface using in situ scanning tunneling microscopy.
View Article and Find Full Text PDFTwo new porphycenes functionalized with ferrocenyl pendants have been synthesized and characterized spectroscopically and structurally. The porphycene-based emission in porphycene-ferrocene dyads was switched on and off by the reversible control of the ferrocenyl pendant redox states. Transient absorption spectroscopy with a femtosecond laser-pulsed technique has successfully detected the picosecond charge-separated excited state of the dyad upon Q-band excitation of the porphycene ring.
View Article and Find Full Text PDFRedetermination of di-aqua-tris-(4-oxo-pent-2-en-2-olato-κ(2) O,O')lanthanum(III).
Acta Crystallogr Sect E Struct Rep Online
July 2014
The structure of the title compound, [La(C5H7O2)3(H2O)2], has been redetermined to modern standards with anisotropic displacement parameters for all non-H atoms and the hydrogen-bonding pattern unambiguously established [for the previous study, see Phillips et al. (1968 ▶). Inorg.
View Article and Find Full Text PDFHydrogenated tetrapropylporphycenes, 2,3-dihydro-2,7,12,17-tetrapropylporphycene 1 and its Ni(II) complex 2, have been prepared and the hydrogenation effects on their electronic structure characterized. A one-electron reduction of 2 promotes dehalogenation of organic halides whose observation is unprecedented for the porphycene compounds.
View Article and Find Full Text PDFAqua-bis-(1,1,1,5,5,5-hexa-fluoro-acetyl-acetonato)[4'-(4-pyrid-yl)-2,2':6',2''-terpyridine]-ytterbium(III) chloride methanol monosolvate monohydrate.
Acta Crystallogr Sect E Struct Rep Online
January 2012
The title compound, [Yb(C(5)HF(6)O(2))(2)(C(20)H(14)N(4))(H(2)O)]Cl·CH(3)OH·H(2)O, adopts an eight-coordinated geometry around the Yb(III) atom consisting of a 4'-(4-pyrid-yl)-2,2':6',2''-terpyridine (pytpy) ligand, two 1,1,1,5,5,5-hexa-fluoro-acetyl-acetonate (hfac) anions and an aqua ligand. In the solid state, the compound forms supra-molecular chains running along the b-axis via inter-molecular hydrogen bonds between the Yb-OH(2) unit and the N-atom donor of the 4-pyridyl pendant of pytpy, with an O⋯N distance of 2.686 (4) Å.
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