Photo-Induced Phase Transition in an Electron–Lattice Correlated System –Future Role of a Time-Resolved X-ray Measurement for Materials Science–

Koshihara, Shin‐ya; Adachi, Shin‐ichi

doi:10.1143/jpsj.75.011005

Cited by 54 publications

(27 citation statements)

References 45 publications

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“…hydrophobic cavity ͉ molecular movie ͉ protein dynamics ͉ time-resolved crystallography L ocalized electronic excitation by photons often induces largescale structural modulations and novel physical properties in condensed matter (1,2). Myoglobin (Mb), often referred to as the hydrogen atom of biology and a paradigm of complexity (3), has played a central role in research on the photo-induced response of proteins and migration of gases, solvents, and ligands in the protein matrix (3,4).…”

mentioning

confidence: 99%

Visualizing breathing motion of internal cavities in concert with ligand migration in myoglobin

Tomita

Sato

Ichiyanagi

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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110

109

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Proteins harbor a number of cavities of relatively small volume. Although these packing defects are associated with the thermodynamic instability of the proteins, the cavities also play specific roles in controlling protein functions, e.g., ligand migration and binding. This issue has been extensively studied in a well-known protein, myoglobin (Mb). Mb reversibly binds gas ligands at the heme site buried in the protein matrix and possesses several internal cavities in which ligand molecules can reside. It is still an open question as to how a ligand finds its migration pathways between the internal cavities. Here, we report on the dynamic and sequential structural deformation of internal cavities during the ligand migration process in Mb. Our method, the continuous illumination of native carbonmonoxy Mb crystals with pulsed laser at cryogenic temperatures, has revealed that the migration of the CO molecule into each cavity induces structural changes of the amino acid residues around the cavity, which results in the expansion of the cavity with a breathing motion. The sequential motion of the ligand and the cavity suggests a self-opening mechanism of the ligand migration channel arising by induced fit, which is further supported by computational geometry analysis by the Delaunay tessellation method. This result suggests a crucial role of the breathing motion of internal cavities as a general mechanism of ligand migration in a protein matrix.hydrophobic cavity ͉ molecular movie ͉ protein dynamics ͉ time-resolved crystallography L ocalized electronic excitation by photons often induces largescale structural modulations and novel physical properties in condensed matter (1, 2). Myoglobin (Mb), often referred to as the hydrogen atom of biology and a paradigm of complexity (3), has played a central role in research on the photo-induced response of proteins and migration of gases, solvents, and ligands in the protein matrix (3, 4). Despite the large number of details known about Mb dynamics, it remains unclear how a ligand molecule escapes from the protein matrix to the solvent and how the protein matrix responds to the ligand migration at the atomic level. A number of time-resolved spectroscopic measurements of Mb photoproducts have revealed a complex ligand-binding reaction with multiple kinetic intermediates (4-8). After dissociation from the heme iron atom, ligand gas molecules either rebind internally from the distal pocket (DP) (Fig. 1) or escape into the solvent. It has been deduced that the escape of the ligand is assisted by the thermal f luctuations that transiently open exit channels. Lowering the temperature slows down the thermal f luctuations, and the internal binding process becomes dominant (4, 5).The multiple kinetic intermediates scheme of Mb has motivated researchers to characterize the structural features of the the intermediates by using both time-resolved (9-14) and cryogenic crystallographic measurements (15)(16)(17)(18)(19)(20)(21)(22). A general picture emerging from these experiments is that Mb...

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mentioning

confidence: 99%

Visualizing breathing motion of internal cavities in concert with ligand migration in myoglobin

Tomita

Sato

Ichiyanagi

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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110

109

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“…Figure 6a shows the transient reflectivity spectrum ranging from 69 meV to 2.1 eV at 100 fs after photoexcitation together with the static spectra in the high-and low-temperature phases. The photon energy of the pump pulse was 1.58 eV, where one of the CT bands was located, and the excitation photon density was 7 × 10 20 photons/cm 3 . The density of the EDO-TTF molecule estimated from the crystal parameters was 3 × 10 21 molecules/cm 3 .…”

Section: Photoinduced Phase Transition In Strong Electron-lattice Intmentioning

confidence: 99%

“…Photoirradiation induces a transition between these phases and this phenomenon is called photoinduced phase transition (PIPT) [2,3]. Many types of interactions exist in the crystal between the constitutive atoms or molecules.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Phase Transition in Strongly Electron-Lattice and Electron–Electron Correlated Molecular Crystals

2012

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Strongly electron-lattice-and electron-electron-correlated molecular crystals, such as charge transfer (CT) complexes, are often sensitive to external stimuli, e.g., photoexcitation, due to the cooperative or competitive correlation of various interactions present in the crystals. These crystals are thus productive targets for studying photoinduced phase transitions (PIPTs). Recent advancements in research on the PIPT of CT complexes, especially Et 2 Me 2 Sb[Pd(dmit) 2 ] 2 and (EDO-TTF) 2 PF 6 , are reviewed in this report. The former exhibits a photoinduced insulator-to-insulator phase transition with clearly assigned spectral change. We demonstrate how to find the dynamics of PIPT using this system. The latter exhibits a photoinduced hidden state as an initial PIPT process. Wide energy ranged time-resolved spectroscopy can probe many kinds of photo-absorption processes, i.e., intra-molecular and inter-molecular electron excitations and intramolecular and electron-molecular vibrations. The photoinduced spectral changes in these photo-absorption processes reveal various aspects of the dynamics of PIPT, including electronic structural changes, lattice structural changes, and molecular deformations. The complexities of the dynamics of the latter system were revealed by our measurements. OPEN ACCESSCrystals 2012, 2 1068

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“…In fact, the uniaxial strain perpendicular to the conducting layer of (EDO-TTF) 2 PF 6 increased the metal-insulator transition temperature markedly (>60 K at 4 kbar) [18]. The susceptibility to an instantaneous stimulus was proved by the examination of the photo-induced phase transition (PIPT) [9,10]. By irradiating laser light with a pulse width of 0.12 ps, the low-temperature phase of the complex showed an abrupt change in reflectivity.…”

Section: Photo-induced Phase Transition Of (Edo-ttf) 2 Pfmentioning

confidence: 99%

“…Among them, the metal-insulator transition observed for (EDO-TTF) 2 PF 6 demonstrates the multi-instability of the metallic state [8]. Furthermore, the low-temperature insulator state exhibits an ultra-fast and highly efficient photo-induced phase transition [9,10]. In these transitions, the correlation between the electric state and lattice (and/or molecular) vibration is important.…”

Section: Introductionmentioning

confidence: 99%

Organic metal (EDO-TTF)₂PF₆with multi-instability

Yamochi

Koshihara

2009

Science and Technology of Advanced Materials

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The multi-instability of the electronic structure of (EDO-TTF) 2 PF 6 , where EDO-TTF means ethylene-dioxytetrathiafulvalene, is reviewed. This complex showed the metal-insulator transition at 280 K associated with distinct molecular deformations. The mechanism is interpreted as the cooperation of Peierls transition, charge ordering, and the order-disorder transition of the countercomponent. The charge ordering pattern in the low-temperature phase is of the novel [0, 0, 1, 1] type. The sensitivity of the electronic state to external perturbations is demonstrated applying not only static but also instantaneous stimuli. In the latter case, the photo-induced phase transition is ultrafast and highly efficient. One photon causes the transition of several hundreds of donor molecules in the low-temperature phase to relax into a highly conducting metastable state within about 1.5 ps. In the early stage of the transient state, the charge ordering of the [1, 0, 1, 0] type occurs. As for the chemical modifications of this material, the partial deuteration of this complex increases the metal-insulator transition temperature. The introduction of a methyl group greatly modulates the electronic structure of the complex, i.e. (methyl-EDO-TTF) 2 X (X = BF 4 , ClO 4 ) shows a two-dimensional electronic structure. The working hypotheses for developing the systems with multi-instability are described.

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Photo-Induced Phase Transition in an Electron–Lattice Correlated System –Future Role of a Time-Resolved X-ray Measurement for Materials Science–

Cited by 54 publications

References 45 publications

Visualizing breathing motion of internal cavities in concert with ligand migration in myoglobin

Visualizing breathing motion of internal cavities in concert with ligand migration in myoglobin

Photoinduced Phase Transition in Strongly Electron-Lattice and Electron–Electron Correlated Molecular Crystals

Organic metal (EDO-TTF)₂PF₆with multi-instability

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Photo-Induced Phase Transition in an Electron–Lattice Correlated System –Future Role of a Time-Resolved X-ray Measurement for Materials Science–

Cited by 54 publications

References 45 publications

Visualizing breathing motion of internal cavities in concert with ligand migration in myoglobin

Visualizing breathing motion of internal cavities in concert with ligand migration in myoglobin

Photoinduced Phase Transition in Strongly Electron-Lattice and Electron–Electron Correlated Molecular Crystals

Organic metal (EDO-TTF)2PF6with multi-instability

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Product

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Organic metal (EDO-TTF)₂PF₆with multi-instability