Haruo Shizuka

Bio: Haruo Shizuka is an academic researcher from Gunma University. The author has contributed to research in topics: Excited state & Flash photolysis. The author has an hindex of 37, co-authored 193 publications receiving 3704 citations.

Effects of Electronic Structures on the Excited-State Intramolecular Proton Transfer of 1-Hydroxy-2-acetonaphthone and Related Compounds

Abstract: Effects of electronic structures on the excited-state intramolecular proton transfer (ESIPT) of 1-hydroxy-2-acetonaphthone (1H2AN) and its related compounds [1-hydroxy-2-naphthaldehyde (1H2NA) and ...

The 2pπ*–3dπ interaction in aromatic silanes. Fluorescence from the 1(2pπ, 3dπ) intramolecular charge-transfer state

Abstract: The 2pπ*–3dπ interaction in the excited state of aromatic silanes has been studied by means of absorption and emission spectroscopy. Broad and structureless fluorescence spectra of phenyldisilanes and naphthyldisilanes with large Stokes shifts have been observed and they have been attributed to the emissions from the intramolecular charge-transfer (c.t.) states with large dipole moments. Evidence that the c.t. emission originates from the 1(2pπ, 3dπ) state produced by the 2pπ*(aromatic ring)→ 3dπ(Si—Si bond) intramolecular charge transfer is given by the effect of steric twisting on the emission. It is shown that the fast formation (⩽ 1 ns) of the c.t. state from the locally excited state 1(π, π*)1B2(or 1Lb) of phenyldisilanes takes place, followed by rapid decay (⩽ 1 ns) of the intersystem crossing 1(2pπ, 3dπ)→3(π, π*). However, no c.t. emission has been observed for aromatic monosilanes and polycyclic aromatic disilanes (aromatic rings 3) even in fluid polar solvents. The 2pπ*→3dπ intramolecular c.t. mechanism is discussed in comparison with that of the twisted intramolecular charge-transfer (t.i.c.t.) state.

Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer States and Structures

Abstract: 6. Rehybridization of the Acceptor (RICT) 3908 7. Planarization of the Molecule (PICT) 3909 III. Fluorescence Spectroscopy 3909 A. Solvent Effects and the Model Compounds 3909 1. Solvent Effects on the Spectra 3909 2. Steric Effects and Model Compounds 3911 3. Bandwidths 3913 4. Isoemissive Points 3914 B. Dipole Moments 3915 C. Radiative Rates and Transition Moments 3916 1. Quantum Yields and Radiationless Deactivation Processes 3916

Proton-Coupled Electron Transfer

Abstract: ▪ Abstract Proton-coupled electron transfer (PCET) is an important mechanism for charge transfer in a wide variety of systems including biology- and materials-oriented venues. We review several are...

Fluorescent Porous Polymer Films as TNT Chemosensors: Electronic and Structural Effects

Abstract: The synthesis, spectroscopy, and fluorescence quenching behavior of pentiptycene-derived phenyleneethynylene polymers, 1−3, are reported. The incorporation of rigid three-dimensional pentiptycene moieties into conjugated polymer backbones offers several design advantages for solid-state (thin film) fluorescent sensory materials. First, they prevent π-stacking of the polymer backbones and thereby maintain high fluorescence quantum yields and spectroscopic stability in thin films. Second, reduced interpolymer interactions dramatically enhance the solubility of polymers 1−3 relative to other poly(phenyleneethynylenes). Third, the cavities generated between adjacent polymers are sufficiently large to allow diffusion of small organic molecules into the films. These advantages are apparent from comparisons of the spectroscopic and fluorescence quenching behavior of 1−3 to a related planar electron-rich polymer 4. The fluorescence attenuation (quenching) of polymer films upon exposure to analytes depends on seve...

Charge Separation in Excited States of Decoupled Systems—TICT Compounds and Implications Regarding the Development of New Laser Dyes and the Primary Process of Vision and Photosynthesis

Abstract: The understanding of the dual fluorescence of certain aromatic systems has greatly advanced in recent years. The accompanying large charge separation has been shown to be linked to a twisted (or small overlap) arrangement of the chromophores. Recent theoretical models are able to describe the excited-state twisting of both single bonds (TICT compounds) and double bonds (olefins) in a unified picture. These models can help to elucidate the photophysical behavior of many organic, inorganic, and biologically relevant compounds, and their application to laser dyes and fluorescent probes provides a route to new “tailor-made” fluorescent materials. Applied to the primary processes of vision and photosynthesis, these models can lead to a deeper understanding of basic photobiological processes.