▪ 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

Three-dimensional quasiclassical trajectory calculations have been performed for the C( 3 P) + HI/DI→CH (X 2 Π)/CD (X 2 Π) + I reactions by using LEPS potential energy surfaces. The experimental vibrational distribution of the product CH has been compared with the calculated one. It has been qualitatively suggested that the potential energy surface for the C + HI reaction is highly attractive, and that the smaller product vibrational energy disposal, 〈ƒ ν 〉, relative to those of the reactions of Cl, F, and O with HI is due to secondary encounters on its surface. This conclusion has been also supported by the calculated isotope effect on the product vibrational energy disposal for the C + HI/DI reactions.

Quasiclassical trajectory study of the reaction C(3P)+HI→CH(X 2Π) + I

Vibrational Mode‐Specific Tunneling Splittings in the A States of Deuterated Tropolones

1-Cyano-trans-1,2-bis(4′-methylbiphenyl)ethylene (CN-MBE) is a prototypical molecule that exhibits aggregation-induced emission (AIE); however, there is very little information about its molecular ...

Two Isomers of a Cyanostilbene Derivative in Viscous Solution Observed by Fluorescence Spectroscopy

Electron spin resonance absorption has been observed in a single-crystal solid solution of benzo[f]quinoline in biphenyl under irradiation at 120 K with light from a high-pressure mercury lamp. The fine structure of the resonance spectrum observed at 9.25 GHz can be described by the spin HamiltonianH=βH·g·S+D[S_z^2-\frac13S(S+1)]+E(S_x^2-S_y^2) in which S=1, D=±0.09926(18) cm−1, E=\mp0.04781(6) cm−1, gxx=2.0024(6), gyy=2.0018(4), and gzz=2.0018(4); the z axis is normal to the molecular plane, the x and y axes being the in-plane fine-structure principal axes. The principal x axis deviates by ±4° from the biphenyl long axis and the principal z axis by 7° from the biphenyl out-of-plane axis. The phosphorescence spectra and lifetimes have been measured both at 77 K and at 4.2 K. Marked doublet splittings were observed in the phosphorescence bands at 4.2 K, suggesting a large guest-host interaction.

ESR Study of the Phosphorescent State of Benzo[f]quinoline

Nascent vibrational distribution of CO+(A2Π) produced from the He(23S) + CO Penning ionization has been determined by optical emission spectroscopy. Experiments were performed by using a new low-pressure apparatus utilizing a mild expansion of helium metastable atoms generated in a flow tube.

Hiroshi Sekiya

Papers

Quasiclassical trajectory study of the reaction C(3P)+HI→CH(X 2Π) + I

Vibrational Mode‐Specific Tunneling Splittings in the A States of Deuterated Tropolones

Two Isomers of a Cyanostilbene Derivative in Viscous Solution Observed by Fluorescence Spectroscopy

ESR Study of the Phosphorescent State of Benzo[f]quinoline

Nascent Vibrational Distribution of CO+(A2Π) Resulting from the He(23S) + CO Penning Ionization in a Low-pressure Apparatus