Mikio Yagi

artykuł

Triplet–triplet energy transfer between UV absorbers in solutions at room temperature

Suzuna Matsumoto, Ryo Kumasaka, Mikio Yagi, Azusa Kikuchi

Journal of Photochemistry and Photobiology A: Chemistry > 2017 > 346 > C > 396-400

The triplet–triplet energy transfer between UV absorbers at room temperature has not been reported in scientific literature, although sunscreens are used at room temperature. In the present study, the bimolecular rate constants of the triplet–triplet energy transfer from a UV-A absorber, menthyl anthranilate (MA, tradename Meradimate), to typical UV-B absorbers, octocrylene (OCR, tradename Parsol...

artykuł

Energy-donor phosphorescence quenching study of triplet–triplet energy transfer between UV absorbers

Azusa Kikuchi, Yuya Nakabai, Nozomi Oguchi-Fujiyama, Kazuyuki Miyazawa, więcej

Journal of Luminescence > 2015 > 166 > Complete > 203-208

The intermolecular triplet–triplet energy transfer from a photounstable UV-A absorber, 4-tert-butyl-4′-methoxydibenzoylmethane (BMDBM), to UV-B absorbers, 2-ethylhexyl 4-methoxycinnamate (octyl methoxycinnamate, OMC), octocrylene (OCR) and dioctyl 4-methoxybenzylidenemalonate (DOMBM) has been observed using a 355nm laser excitation in rigid solutions at 77K. The decay curves of the energy-donor phosphorescence...

artykuł

Photoexcited States of UV Absorbers, Benzophenone Derivatives

Ryo Kumasaka, Azusa Kikuchi, Mikio Yagi

Photochemistry and Photobiology > 90 > 4 > 727 - 733

The UV absorption, phosphorescence and phosphorescence‐excitation spectra of benzophenone (BP) derivatives used as organic UV absorbers have been observed in rigid solutions at 77 K. The triplet–triplet absorption spectra have been observed in acetonitrile at room temperature. The BP derivatives studied are 2,2′,4,4′‐tetrahydroxybenzophenone (BP‐2), 2‐hydroxy‐4‐methoxybenzophenone (BP‐3), 2,2′‐dihydroxy‐4,4′‐dimethoxybenzophenone...

artykuł

Triplet–Triplet Energy Transfer from a UV‐A Absorber Butylmethoxydibenzoylmethane to UV‐B Absorbers

Azusa Kikuchi, Nozomi Oguchi‐Fujiyama, Kazuyuki Miyazawa, Mikio Yagi

Photochemistry and Photobiology > 90 > 3 > 511 - 516

The phosphorescence decay of a UV‐A absorber, 4‐tert‐butyl‐4′‐methoxydibenzolymethane (BMDBM) has been observed following a 355 nm laser excitation in the absence and presence of UV‐B absorbers, 2‐ethylhexyl 4‐methoxycinnamate (octyl methoxycinnamate, OMC) and octocrylene (OCR) in ethanol at 77 K. The lifetime of the lowest excited triplet (T₁) state of BMDBM is significantly reduced in the presence...

artykuł

Photoexcited Singlet and Triplet States of a UV Absorber Ethylhexyl Methoxycrylene

Azusa Kikuchi, Yuki Hata, Ryo Kumasaka, Yuichi Nanbu, więcej

Photochemistry and Photobiology > 89 > 3 > 523 - 528

The excited states of UV absorber, ethylhexyl methoxycrylene (EHMCR) have been studied through measurements of UV absorption, fluorescence, phosphorescence and electron paramagnetic resonance (EPR) spectra in ethanol. The energy levels of the lowest excited singlet (S₁) and triplet (T₁) states of EHMCR were determined. The energy levels of the S₁ and T₁ states of EHMCR are much lower than those of...

artykuł

Direct observation of the intermolecular triplet–triplet energy transfer from UV-A absorber 4-tert-butyl-4′-methoxydibenzoylmethane to UV-B absorber octyl methoxycinnamate

Azusa Kikuchi, Mikio Yagi

Chemical Physics Letters > 2011 > 513 > 1-3 > 63-66

Triplet energy transfer (TET) is an important photostabilization process for organic UV absorbers, such as 4-tert-butyl-4′-methoxydibenzoylmethane (BM-DBM) and octyl methoxycinnamate (OMC). To characterize interactions between UV absorbers as TET the interactions between BM-DBM and OMC have been studied through measurements of EPR and time-resolved phosphorescence spectra. The EPR B _min signals...

rozdział

Macrobending indicator for evaluation of fiber macrobending and splice loss

Shiro Ryu, Mikio Yagi

OECC 2010 Technical Digest > 322 - 323

2010 15th OptoElectronics and Communications Conference (OECC 2010)

Detailed investigation of a macrobending indicator that expresses a degree of fiber macrobending is carried out. It has been made clear that the indicator is also effective for evaluating wavelength dependence of fusion splice loss.

artykuł

Optical and Electron Paramagnetic Resonance Studies of the Excited States of 4- tert -Butyl-4′-Methoxydibenzoylmethane and 4- tert -Butyl-4′-Methoxydibenzoylpropane

Azusa Kikuchi, Nozomi Oguchi, Mikio Yagi

The Journal of Physical Chemistry A > 2009 > 113 > 48 > 13492 - 13497

artykuł

The phosphorescent triplet states of aza-aromatics and their protonated cations in rigid solutions of ethanol and 1-butyl-3-methylimidazolium hexafluorophosphate

Ryuichiro Matsuo, Tomoaki Uchiyama, Kentarou Mogi, Shunya Kaneko, więcej

Journal of Photochemistry & Photobiology, A: Chemistry > 2009 > 203 > 1 > 18-23

The lowest excited triplet (T ₁ ) states of 2,2′-bipyridine (BPY), 6,6′-dimethyl-2,2′-bipyridine (DMBPY), 2,2′-biquinoline (BQ), 2-phenylpyridine (2-PPY), 3-phenylpyridine (3-PPY), 4-phenylpyridine (4-PPY), quinoline (QN) and isoquinoline (iso-QN) have been studied through measurements of the phosphorescence and EPR spectra in 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF ...

artykuł

Direct measurements of absolute concentration and lifetime of singlet oxygen in the gas phase by electron paramagnetic resonance

Keisuke Hasegawa, Kenji Yamada, Ryouji Sasase, Ryota Miyazaki, więcej

Chemical Physics Letters > 2008 > 457 > 4-6 > 312-314

Electron paramagnetic resonance (EPR) spectroscopy was employed to determine the lifetime and absolute concentration of singlet oxygen, O ₂ ( ¹ Δ _g ), in the gas phase. O ₂ ( ¹ Δ _g ) molecules were generated by gas-phase photosensitization with octafluoronaphthalene. The absolute concentration of O ₂ ( ¹ Δ _g ) at total pressure...

artykuł

Optical and electron paramagnetic resonance studies of the lowest excited triplet states of 1-phenyl-4-(4-pyridyl)butadiyne and its protonated cation

Ryo Ito, Daisuke Suzuki, Yasushi Yokoyama, Mikio Yagi

Chemical Physics Letters > 2006 > 420 > 1-3 > 261-266

The lowest excited triplet (T ₁ ) states of 1-phenyl-4-(4-pyridyl)butadiyne (4-PPB) and its protonated cation (4-PPBH ⁺ ) have been studied through measurements of the phosphorescence, time-resolved EPR and parallel-polarized EPR spectra. Unusually large zero-field splittings were observed for 4-PPB and 4-PPBH ⁺ . The replacement of CH by a nitrogen atom appears to have little...

artykuł

Time-resolved electron paramagnetic resonance of the lowest excited triplet state of phenazinium cation

Makoto Deguchi, Daisuke Suzuki, Ryo Ito, Michiko Matsumoto, więcej

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy > 2005 > 61 > 6 > 1147-1151

Time-resolved and steady-state electron paramagnetic resonance (EPR) spectra have been observed for the lowest excited triplet (T ₁ ) states of phenazine (Phz) and its singly protonated cation (phenazinium) in sulfuric acid−ethanol mixtures at 77K. The single protonation appears to have little effect on the anisotropic sublevel populating rates of the T ₁ state of phenazine. However,...

artykuł

Synthesis and structure–activity relationship for new series of 4-Phenoxyquinoline derivatives as specific inhibitors of platelet-derived growth factor receptor tyrosine kinase

Kazuo Kubo, Shin-ichi Ohyama, Toshiyuki Shimizu, Atsuya Takami, więcej

Bioorganic & Medicinal Chemistry > 2003 > 11 > 23 > 5117-5133

We discovered a new series of 4-phenoxyquinoline derivatives as potent and selective inhibitors of the platelet-derived growth factor receptor (PDGFr) tyrosine kinase. We researched the highly potent and selective inhibitors on the basis of both PDGFr and epidermal growth factor receptor (EGFr) inhibitory activity. First, we found a compound, Ki6783 (1), which inhibited PDGFr autophosphorylation at...

artykuł

Conformations and Zero-Field Splittings in the Lowest Excited Triplet States of m eta - and p ara -Polyphenyl Molecules

Jiro Higuchi, Kazuyoshi Hayashi, Mikio Yagi, Hiroshi Kondo

The Journal of Physical Chemistry A > 2002 > 106 > 37 > 8609 - 8618

artykuł

Electron Paramagnetic Resonance Studies of the Lowest Triplet States of Polyphenyl Molecules in Rigid Glasses

Jiro Higuchi, Kazuyoshi Hayashi, Kanekazu Seki, Mikio Yagi, więcej

The Journal of Physical Chemistry A > 2001 > 105 > 25 > 6084 - 6091

artykuł

Role of PDGF B-Chain and PDGF Receptors in Rat Tubular Regeneration after Acute Injury

Takahiko Nakagawa, Masakiyo Sasahara, Masakazu Haneda, Hideo Kataoka, więcej

The American Journal of Pathology > 1999 > 155 > 5 > 1689-1699

Various polypeptide growth factors are generally considered to be involved in the regulation of the nephrogenic process both after acute renal injury and during renal development. Because platelet-derived growth factor B-chain (PDGF-B) has been reported to be expressed in immature tubulus of the developing kidney, PDGF-B could play a role in the process of tubulogenesis. We examined the expression...

artykuł

A novel series of 4-phenoxyquinolines: potent and highly selective inhibitors of PDGF receptor autophosphorylation

Kazuo Kubo, Toshiyuki Shimizu, Shin-ichi Ohyama, Hideko Murooka, więcej

Bioorganic & Medicinal Chemistry Letters > 1997 > 7 > 23 > 2935-2940

A novel series of 4-phenoxyquinolines, some of which showed potent and highly selective inhibitory activities for PDGF receptor autophosphorylation, was discovered. Interestingly, their structures were very similar to those of the selective inhibitors for EGF receptor autophosphorylation.

artykuł

Time-resolved electron paramagnetic resonance study of the lowest excited triplet states of trans-cinnamic acid and trans-cinnamate anion

Shinya Kakuho, Kanekazu Seki, Mikio Yagi

Chemical Physics Letters > 1997 > 277 > 4 > 326-330

Time-resolved and steady-state electron paramagnetic resonance spectra have been observed for the lowest excited triplet (T ₁ ) states of trans-cinnamic acid (RCOOH) and trans-cinnamate anion (RCOO ^- ) in methanol-water and in stretched poly(vinyl alcohol) films at 77 K. The zero-field splitting parameters D and E in the T ₁ state slightly increase on deprotonation...

artykuł

Selective Inhibition of Platelet-Derived Growth Factor (PDGF) Receptor Autophosphorylation and PDGF-Mediated Cellular Events by a Quinoline Derivative

Mikio Yagi, Shinichiro Kato, Yoshiko Kobayashi, Kazuo Kubo, więcej

Experimental Cell Research > 1997 > 234 > 2 > 285-292

This report describes the biological effects of our original compound, Ki6783 ((3,4-dimethoxy)-4-phenoxy-6,7-dimethoxyquinoline), a potent and selective inhibitor of platelet-derived growth factor (PDGF) receptor autophosphorylation. This compound strongly inhibited autophosphorylation of the PDGF β-receptor in cultured rat glomerular mesangial cells (MC) bearing this receptor (IC ₅₀ 0.1 μM),...

artykuł

Counterion and position-dependent methylation effects on the excited states of zinc(II) complexes with 1,10-phenanthroline

Masafumi Senoue, Takashi Iwaki, Kanekazu Seki, Mikio Yagi

Journal of Photochemistry & Photobiology, A: Chemistry > 1996 > 101 > 2-3 > 257-263

Time-resolved electron paramagnetic resonance and luminescence spectra have been observed for the lowest excited states of 1,10-phenanthroline (phen), 2-methyl-1,10-phenanthroline (2-Mephen), 2,9-dimethyl-1,10-phenanthroline (2,9-Me ₂ phen), 4,7-Me ₂ phen, 5,6-Me ₂ phen and their Zn ²⁺ complexes in rigid solutions at 77 K. The sublevel preferentially populated by intersystem...

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Wyniki wyszukiwania dla: Mikio Yagi

Triplet–triplet energy transfer between UV absorbers in solutions at room temperature

Energy-donor phosphorescence quenching study of triplet–triplet energy transfer between UV absorbers

Photoexcited States of UV Absorbers, Benzophenone Derivatives

Triplet–Triplet Energy Transfer from a UV‐A Absorber Butylmethoxydibenzoylmethane to UV‐B Absorbers

Photoexcited Singlet and Triplet States of a UV Absorber Ethylhexyl Methoxycrylene

Direct observation of the intermolecular triplet–triplet energy transfer from UV-A absorber 4-tert-butyl-4′-methoxydibenzoylmethane to UV-B absorber octyl methoxycinnamate

Macrobending indicator for evaluation of fiber macrobending and splice loss

Optical and Electron Paramagnetic Resonance Studies of the Excited States of 4- tert -Butyl-4′-Methoxydibenzoylmethane and 4- tert -Butyl-4′-Methoxydibenzoylpropane

The phosphorescent triplet states of aza-aromatics and their protonated cations in rigid solutions of ethanol and 1-butyl-3-methylimidazolium hexafluorophosphate

Direct measurements of absolute concentration and lifetime of singlet oxygen in the gas phase by electron paramagnetic resonance

Optical and electron paramagnetic resonance studies of the lowest excited triplet states of 1-phenyl-4-(4-pyridyl)butadiyne and its protonated cation

Time-resolved electron paramagnetic resonance of the lowest excited triplet state of phenazinium cation

Synthesis and structure–activity relationship for new series of 4-Phenoxyquinoline derivatives as specific inhibitors of platelet-derived growth factor receptor tyrosine kinase

Conformations and Zero-Field Splittings in the Lowest Excited Triplet States of m eta - and p ara -Polyphenyl Molecules

Electron Paramagnetic Resonance Studies of the Lowest Triplet States of Polyphenyl Molecules in Rigid Glasses

Role of PDGF B-Chain and PDGF Receptors in Rat Tubular Regeneration after Acute Injury

A novel series of 4-phenoxyquinolines: potent and highly selective inhibitors of PDGF receptor autophosphorylation

Time-resolved electron paramagnetic resonance study of the lowest excited triplet states of trans-cinnamic acid and trans-cinnamate anion

Selective Inhibition of Platelet-Derived Growth Factor (PDGF) Receptor Autophosphorylation and PDGF-Mediated Cellular Events by a Quinoline Derivative

Counterion and position-dependent methylation effects on the excited states of zinc(II) complexes with 1,10-phenanthroline

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