Diarylethene Self-Assembled Monolayers: Cocrystallization and Mixing-Induced Cooperativity Highlighted by Scanning Tunneling Microscopy at the Liquid/Solid Interface

International audienceThe control over 2-D multi-component molecular orderings on surfaces is a key technology to realize advanced materials with stimuli-responsive properties. The fractional coverage (θ) at a given concentration can be determined from two parameters: the equilibrium constant (Ke) and the degree of cooperativity (σ). The parameters for the formation of self-assembled monolayer of pure diarylethene isomers were obtained by STM measurements on HOPG. These mono-component parameters were used as references to highlight a cocrystallization process between the open-and closed-ring isomers. Moreover it was observed that the presence of the closed-ring isomer induces cooperativity in the formation of the molecular ordering of the open-ring isomer. The quantitative analysis of the ordering formation process by using a model simulation presented in this work provides a better understanding of mixing of components in a molecular ordering and photoinduced interchanges at the liquid/solid interface

Cooperativity Analysis of the Open-, Closed-and Annulated-Isomers of Diarylethene that form 2-D Ordering at the Liquid/Solid Interface and their Photochemical Interchanges

International audienc

Diarylethene Self-Assembled Monolayers: Cocrystallization and Mixing-Induced Cooperativity Highlighted by Scanning Tunneling Microscopy at the Liquid/Solid Interface

International audienceThe control over 2-D multi-component molecular orderings on surfaces is a key technology to realize advanced materials with stimuli-responsive properties. The fractional coverage (θ) at a given concentration can be determined from two parameters: the equilibrium constant (Ke) and the degree of cooperativity (σ). The parameters for the formation of self-assembled monolayer of pure diarylethene isomers were obtained by STM measurements on HOPG. These mono-component parameters were used as references to highlight a cocrystallization process between the open-and closed-ring isomers. Moreover it was observed that the presence of the closed-ring isomer induces cooperativity in the formation of the molecular ordering of the open-ring isomer. The quantitative analysis of the ordering formation process by using a model simulation presented in this work provides a better understanding of mixing of components in a molecular ordering and photoinduced interchanges at the liquid/solid interface. (1) Sakano, T.; Imaizumi, Y.; Hirose, T.; Matsuda, K. Chem. Lett. 2013, 42, 1537. (2) Yokoyama, S.; Hirose, T.; Matsuda, K. Chem. Commun. 2014, 50, 5964. (3) Frath, D.; Sakano, T.; Imaizumi, Y.; Yokoyama, S.; Hirose, T.; Matsuda, K. Chem. Eur. J. 2015, 21, 11350

Bridging Pico-to-Nanonewtons with a Ratiometric Force Probe for Monitoring Nanoscale Polymer Physics Before Damage

Understanding the transmission of nanoscale forces in the pico-to-nanonewton range is important in polymer physics. While physical approaches have limitations in analyzing the local force distribution in condensed environments, chemical analysis using force probes is promising. However, there are stringent requirements for probing the local forces generated before structural damage. The magnitude of those forces corresponds to the range below covalent bond scission (from 200 pN to several nN) and above thermal fluctuation (several pN). Here, we report a conformationally flexible dual-fluorescence force probe with a theoretically estimated threshold of approximately 100 pN. This probe enables ratiometric analysis of the distribution of local forces in a stretched polymer chain network. Without changing the intrinsic properties of the polymer, the force distribution was reversibly monitored in real time. Chemical control of the probe location demonstrated that the local stress concentration is twice as biased at crosslinkers than at main chains, particularly in a strain-hardening region. Due to the high sensitivity, the percentage of stressed force probes was estimated to be more than 1000 times higher than the activation rate of a conventional mechanophore.Comment: 21 pages and 5 figures in the main text, and 73 pages and 68 figures in the supplementary material

Bridging pico-to-nanonewtons with a ratiometric force probe for monitoring nanoscale polymer physics before damage

ピンと張られた分子鎖を定量する「羽ばたき型蛍光Force Probe」の開発 --高分子材料の中で力のかかった分子鎖の比率を蛍光イメージングで計測する--. 京都大学プレスリリース. 2022-01-14.Understanding the transmission of nanoscale forces in the pico-to-nanonewton range is important in polymer physics. While physical approaches have limitations in analyzing the local force distribution in condensed environments, chemical analysis using force probes is promising. However, there are stringent requirements for probing the local forces generated before structural damage. The magnitude of those forces corresponds to the range below covalent bond scission (from 200 pN to several nN) and above thermal fluctuation (several pN). Here, we report a conformationally flexible dual-fluorescence force probe with a theoretically estimated threshold of approximately 100 pN. This probe enables ratiometric analysis of the distribution of local forces in a stretched polymer chain network. Without changing the intrinsic properties of the polymer, the force distribution was reversibly monitored in real time. Chemical control of the probe location demonstrated that the local stress concentration is twice as biased at crosslinkers than at main chains, particularly in a strain-hardening region. Due to the high sensitivity, the percentage of the stressed force probes was estimated to be more than 1000 times higher than the activation rate of a conventional mechanophore

Super responder of critical COVID-19 case

This report presents a case of a 74-year-old man who showed dramatic therapeutic response to treatment of coronavirus infectious disease-19 (COVID-19) pneumonia. He reported four-day history of sustained fever and acute progressive dyspnea. He developed severe respiratory failure, underwent urgent endotracheal intubation and showed marked elevation of inflammatory and coagulation markers such as c-reactive protein (CRP), ferritin, lactate dehydrogenase (LDH) and D-dimer. Chest computed tomography (CT) demonstrated diffuse consolidation and ground glass opacity (GGO). We diagnosed critical COVID-19 pneumonia with detailed sick contact history and naso-pharyngeal swab of a reverse-transcriptase-polymerase-chain reaction (RT-PCR) assay testing. He received anti-viral drug, anti-interleukin (IL-6) receptor antagonist and intravenous methylprednisolone. After commencing combined intensive therapy, he showed dramatic improvement of clinical condition, serum biomarkers and radiological findings. Early diagnosis and rapid critical care management may provide meaningful clinical benefit even if severe case

ナノデバイスに向けた二次元表面における光機能性分子の光反応と協同的組織化の研究

京都大学0048新制・課程博士博士(工学)甲第19318号工博第4115号新制||工||1634(附属図書館)32320京都大学大学院工学研究科合成・生物化学専攻(主査)教授 松田 建児, 教授 北川 進, 教授 杉野目 道紀学位規則第4条第1項該当Doctor of Philosophy (Engineering)Kyoto UniversityDGA