▪ 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...

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Proton-Coupled Electron Transfer

Switches, and Actuators Masahiro Irie,*,† Tuyoshi Fukaminato,‡ Kenji Matsuda, and Seiya Kobatake †Research Center for Smart Molecules, Rikkyo University, Nishi-Ikebukuro 3-34-1, Toshima-ku, Tokyo 171-8501, Japan ‡Research Institute for Electronic Science, Hokkaido University, N20, W10, Kita-ku, Sapporo 001-0020, Japan Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto 615-8510, Japan Department of Applied Chemistry, Graduate School of Engineering, Osaka City University, Sugimoto 3-3-138, Sumiyoshi-ku, Osaka 558-8585, Japan

Photochromism of Diarylethene Molecules and Crystals: Memories, Switches, and Actuators

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The π → π* transitions of more than 100 organic dyes from the major classes of chromophores (quinones, diazo, ...) have been investigated using a Time-Dependent Density Functional Theory (TD-DFT) procedure relying on large atomic basis sets and the systematic modeling of solvent effects. These calculations have been performed with pure (PBE) as well as conventional (PBE0) and long-range (LR) corrected hybrid functionals (LC-PBE, LC-ωPBE, and CAM-B3LYP). The computed wavelengths are systematically guided by the percentage of exact exchange included at intermediate interelectronic distance, i.e., the λmax value always follows the PBE > PBE0 > CAM-B3LYP > LC-PBE > LC-ωPBE > HF sequence. The functional giving the best estimates of the experimental transition energies may vary, but PBE0 and CAM-B3LYP tend to outperform all other approaches. The latter functional is shown to be especially adequate to treat molecules with delocalized excited states. The mean absolute error provided by PBE0 is 22 nm (0.14 eV) wit...

TD-DFT Performance for the Visible Absorption Spectra of Organic Dyes: Conventional versus Long-Range Hybrids

Solid state emitters based on excited state intramolecular proton transfer (ESIPT) have been attracting considerable interest since the past few years in the field of optoelectronic devices because of their desirable unique photophysical properties. The photophysical properties of the solid state ESIPT fluorophores determine their possible applicability in functional materials. Less fluorescence quantum efficiencies and short fluorescence lifetime in the solid state are the shortcomings of the existing ESIPT solid state emitters. Designing of ESIPT chromophores with high fluorescence quantum efficiencies and a long fluorescence lifetime in the solid state is a challenging issue because of the unclear mechanism of the solid state emitters in the excited state. Reported design strategies, detailed photophysical properties, and their applications will help in assisting researchers to overcome existing challenges in designing novel solid state ESIPT fluorophores for promising applications. This review highlights recently developed solid state ESIPT emitters with focus on molecular design strategies and their photophysical properties, reported in the last five years.

Excited-state intramolecular proton-transfer (ESIPT)-inspired solid state emitters

The Ne++OCS and He++OCS charge-transfer reactions have been studied by emission spectroscopy in a flowing afterglow. The relative vibrational populations of CO+(A2Π) were determined by observing the CO+(A2Π–X2Σ+) emission system produced from the above reactions. The populations decrease approximately exponentially with the vibrational quantum number.

Vibrational distributions of CO+ (A) produced from the charge-transfer reactions of Ne+ and He+ with OCS at thermal energy

Laser‐induced fluorescence study of the reaction C(3P)+HI→CH(X 2Π)+I at 300 K

Temperature dependent fluorescence spectra arise from change in excited-state intramolecular proton transfer potential of 4′-N,N-dimethylamino-3-hydroxyflavone-doped acetonitrile crystals

Methanol solvation of the Ag+ ion probed with infrared photodissociation spectroscopy of Ag+(CH3OH)n (n = 1–5)

The positive charge distribution in benzene–toluene heterotrimer ions is investigated by photodissociation spectroscopy in the near-infrared (6000–14 000 cm−1) and infrared (2800–3150 cm−1) regions. The electronic spectra of (benzene)1(toluene)2+ and (benzene)2(toluene)1+ in the near-infrared region display a strong band at 9430 and 8330 cm−1, respectively. These bands are ascribed to the charge resonance band; the positive charge is not localized on a single molecule. The vibrational spectrum of (benzene)1(toluene-d8)2+ shows three distinct bands at 3054, 3084, and 3108 cm−1; these bands are assigned to the CH stretching vibrations of the benzene moiety. The similarity of the spectral features to those of the neutral benzene monomer suggests that the benzene molecule in the (benzene)1(toluene)2+ ion has a neutral character. The positive charge is localized on the toluene dimer unit with a structure written as (toluene)2+⋯(benzene)1. The vibrational spectrum of (benzene)2(toluene)1+ bears a resemblance to...

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Hiroshi Sekiya

Papers

Vibrational distributions of CO+ (A) produced from the charge-transfer reactions of Ne+ and He+ with OCS at thermal energy

Laser‐induced fluorescence study of the reaction C(3P)+HI→CH(X 2Π)+I at 300 K

Temperature dependent fluorescence spectra arise from change in excited-state intramolecular proton transfer potential of 4′-N,N-dimethylamino-3-hydroxyflavone-doped acetonitrile crystals

Methanol solvation of the Ag+ ion probed with infrared photodissociation spectroscopy of Ag+(CH3OH)n (n = 1–5)

Positive charge distribution in (benzene)1(toleune)2+ and (benzene)2(toluene)1+ studied by photodissociation spectroscopy