The University of Tokyo · Materials Science
Professor Kazuyuki Ishii's research lab specializes in the photophysical and photochemical properties of metalloporphyrin and phthalocyanine complexes, with a focus on excited-state dynamics, electron paramagnetic resonance (EPR) spectroscopy, and energy/electron transfer processes. The lab employs advanced time-resolved techniques such as time-resolved EPR (TREPR) and transient absorption to investigate spin states, intersystem crossing, and triplet state behavior in functionalized macrocyclic semiconductors. A key research direction involves the development of porphyrin- and phthalocyanine-based probes for biological applications, including ascorbic acid detection and photodynamic therapy (PDT) agents. The lab also explores two-photon processes and selective photoreactions for potential use in biomedical imaging and theranostics.
Figures are computed from collected data and may differ slightly.
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTA Time-Resolved Electron Paramagnetic Resonance Study on the Excited States of Tetraphenylporphinatozinc(II) Coordinated by p-Pyridyl Nitronyl NitroxideKazuyuki Ishii, Jun-ichi Fujisawa, Yasunori Ohba, and Seigo YamauchiView Author Information Institute for Chemical Reaction Science Tohoku University, Katahira 2-1-1 Aoba-ku, Sendai 980, JapanCite this: J. Am. Chem. Soc. 1996, 118, 51, 13079–13080Publication Date (Web):December 25, 1996Publication
The photophysical properties of tetra-tert-butylphthalocyaninatosilicon (SiPc) covalently linked to one or two 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) radicals (R1, R2) have been studied by fluorescence, transient absorption, and time-resolved electron paramagnetic resonance (TREPR) spectroscopies. It is found that the fluorescence quantum yields and lifetimes of R1 and R2 decrease compared with those of (dihydroxy)SiPc ((dihydroxy)SiPc = 6.8 ns, R1 = 4.7 ns and 42 ps, and R2 = 4.7 ns and <
The excited multiplet states of (tetraphenylporphinato)zinc(II) (ZnTPP) coordinated by p-pyridyl nitronyl nitroxide (p-nitpy), ZnTPP−p-nitpy, and of ZnTPP coordinated by m-nitpy, ZnTPP−m-nitpy, were studied by time-resolved electron paramagnetic resonance (TREPR). The TREPR spectra observed at 20 K and 0.5 μs after laser excitation were assigned to the lowest excited doublet (D1) and quartet (Q1) states for both the para and meta complexes. The TREPR spectra of the Q1 state with electron-spin po
Phthalocyaninatosilicon(IV) covalently linked to a 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) radical, SiPc-TEMPO, has been studied by time-resolved electron paramagnetic resonance (TREPR). A TREPR spectrum at 20 K is assigned to the doublet ground (D0) state and the excited quartet (Q1) state consisting of the excited triplet SiPc and the doublet TEMPO radical. The excited quartet spectrum is simulated using zero field splitting parameters D = 4.3 × 10-3 and E = 3.3 × 10-4 cm-1. The D value o
We have applied phthalocyaninatosilicon (SiPc) covalently linked to one or two tetramethyl-1-piperidinyloxyl (TEMPO) radicals as fluorescence probes for detecting ascorbic acid in biological systems.
In this study, we have investigated the photochemical properties and photodynamic effects of ruthenium phthalocyanine (RuPc(CO)(Py)) and naphthalocyanine (RuNc(CO)(Py)) complexes. When a nanosecond-pulsed laser is used, the photodecarbonylation of our Ru complexes efficiently proceeds via stepwise two-photon excitation, while the reaction yields are negligibly small when a continuous-wave (CW) laser is employed. The pulsed laser selective photodecarbonylation decreases the Q-band absorbance, whi
We have previously shown that a DNA topoisomerase I from mouse mammary carcinoma cells is inhibited by heparin.Taking advantage of this enzyme-heparin interaction, we developed a rapid and efficient method of purification of this enzyme to near homogeneity by extraction of chromatin with 0.15 M phosphate buffer followed by two-step column chromatography on heparin-Sepharose and phenyl-Sepharose.Electrophoresis on sodium dodecyl sulfate-polyacrylamide gels revealed that the final preparation is c
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSelective Population from the Excited Multiplet States to the Triplet Ground State in a Phthalocyanine: A New Concept for Controlling Magnetic Properties by PhotoexcitationKazuyuki Ishii, Yoshiharu Hirose, and Nagao KobayashiView Author Information Department of Chemistry, Graduate School of Science Tohoku University, Sendai 980-8578, Japan Cite this: J. Am. Chem. Soc. 1998, 120, 40, 10551–10552Publication Date (Web):September 25, 1998Publication
Organic-polyoxometalate (POM) hybrids have recently attracted considerable interest because of their distinctive properties and wide-ranging applications. For the construction of organic-POM hybrids, porphyrins are promising building units owing to their optical properties and reactivity, including strong visible-light absorption and subsequent singlet-oxygen (<sup>1</sup>O<sub>2</sub>*) generation. However, the practical utilization of porphyrins as photocatalysts and photosensitizers is often
Metallophthalocyanines (MPcs; M = Zn, Mg) coordinated by 4-amino-TEMPO (ATEMPO) in the excited quartet (Q1) state, which are constituted by the excited triplet MPc and doublet ATEMPO, have been studied by a time-resolved electron paramagnetic resonance (TREPR) method. Two components were observed for both the Zn and Mg complexes, and are reasonably assigned to the Q1 and doublet states by calculating the zero field splitting and g value, respectively. The polarization pattern of the Q1 ZnPc-ATEM
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