Faculty Profiles - YAMAGUCHI, Shigehiro

Papers - YAMAGUCHI, Shigehiro

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Long-Lived Charge-Transfer State from B-N Frustrated Lewis Pairs Enchained in Supramolecular Copolymers

Beatrice Adelizzi, Pongphak Chidchob, Naoki Tanaka, Brigitte A. G. Lamers, Stefan C. J. Meskers, Soichiro Ogi, Anja R. A. Palmans, Shigehiro Yamaguchi, E. W. Meijer

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Vol. 142 ( 39 ) page： 16681 - 16689 2020.9

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

The field of supramolecular polymers is rapidly expanding; however, the exploitation of these systems as functional materials is still elusive. To become competitive, supramolecular polymers must display microstructural order and the emergence of new properties upon copolymerization. To tackle this, a greater understanding of the relationship between monomers' design and polymer microstructure is required as well as a set of functional monomers that efficiently interact with one another to synergistically generate new properties upon copolymerization. Here, we present the first implementation of frustrated Lewis pairs into supramolecular copolymers. Two supramolecular copolymers based on p-conjugated O-bridged triphenylborane and two different triphenylamines display the formation of B-N pairs within the supramolecular chain. The remarkably long lifetime and the circularly polarized nature of the resulting photoluminescence emission highlight the possibility to obtain an intermolecular B-N charge transfer. These results are proposed to be the consequences of the enchainment of B-N frustrated Lewis pairs within 1D supramolecular aggregates. Although it is challenging to obtain a precise molecular picture of the copolymer microstructure, the formation of random blocklike copolymers could be deduced from a combination of optical spectroscopic techniques and theoretical simulation.

DOI： 10.1021/jacs.0c06921

Phosphole-Oxide-Based Fluorescent Probe for Super-resolution Stimulated Emission Depletion Live Imaging of the Lysosome Membrane

Chenguang Wang, Masayasu Taki, Keiji Kajiwara, Junwei Wang, Shigehiro Yamaguchi

ACS MATERIALS LETTERS Vol. 2 ( 7 ) page： 705 - 711 2020.7

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Super-resolution imaging techniques have become increasingly important tools to visualize suborganelle structures and dynamic processes in living cells on the nanoscale. However, the utility of these imaging techniques is currently limited by the availability of advanced fluorescent probes that enable the specific labeling of the organelle of interest and provide the absorption/emission properties required for super-resolution imaging techniques. Herein, LysoPB Yellow is presented as a new small-molecule fluorescent probe that can selectivity stain the lysosomal membrane. Its outstandingly high photostability and long fluorescence lifetime are beneficial for its use in super-resolution stimulated emission depletion (STED) microscopy. A lysosomal membrane stained with LysoPB Yellow was successfully visualized by STED imaging in living cells with a full width at half maximum (FWHM) of 70 nm, which is substantially below the diffraction limit of light. Additionally, LysoPB Yellow displayed excellent retention ability and negligible cytotoxicity. Consequently, long-term time-lapse confocal imaging of living cells was successfully conducted, which demonstrates the practical utility of LysoPB Yellow in fluorescence imaging.

DOI： 10.1021/acsmaterialslett.0c00147

Effects of Amino Group Substitution on the Photophysical Properties and Stability of Near-Infrared Fluorescent P-Rhodamines

Marek Grzybowski, Masayasu Taki, Keiji Kajiwara, Shigehiro Yamaguchi

CHEMISTRY-A EUROPEAN JOURNAL Vol. 26 ( 35 ) page： 7912 - 7917 2020.6

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

A series of phosphine oxide-bridged rhodamines (P-rhodamines) bearing various acyclic and cyclic amine moieties, including dimethyl- and diethylamine, azetidine, pyrrolidine and 7-azabicyclo[2,2,1]heptane (7ABH), have been synthesized. The photophysical properties as well as chemical and photostability of these dyes have been studied in detail. Among these dyes, the 7ABH-substituted dye shows stronger fluorescence in the near-infrared (NIR) region, relative to the other P-rhodamines. This dye could be applied to live-cell imaging, wherein lysosomes were selectively stained in a pH-independent manner. It was also found that the ring fusion of the amine moieties gives rise to remarkably redshifted spectra, with absorption and emission maxima at 770 and 820 nm, respectively, spectrally close to that of indocyanine green (ICG). Importantly, the ring-fused P-rhodamines showed much higher photostability than ICG, indicative of their promising utility as the NIR-emissive dyes.

DOI： 10.1002/chem.202000957

Multistep Photoisomerization of Dimesitylboron-Functionalized Stilbene Analogues

Yuxin Ge, Naoki Ando, Lijie Liu, Xiang Wang, Francoise Sauriol, Shigehiro Yamaguchi, Gang Wu, Suning Wang

ORGANIC LETTERS Vol. 22 ( 8 ) page： 3258 - 3262 2020.4

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

Dimesitylboron-functionalized stilbene derivatives have been found to undergo an unusual regioselective photoisomerization upon irradiation at 365 nm. Using NMR to follow the photoreaction, the structures of key reaction intermediates and the final products were established. This photoisomerization occurs in four steps: trans-cis isomerization, Diels-Alder reaction, di-pi-methane rearrangement, and ring opening with [1,3]-H migration. This results in the formation of a rare structure with three fused five-membered rings and a six-membered one.

DOI： 10.1021/acs.orglett.0c01042

Donor-Acceptor Materials Exhibiting Thermally Activated Delayed Fluorescence Using a Planarized N-Phenylbenzimidazole Acceptor

Ethan R. Sauve, Jaesuk Paeng, Shigehiro Yamaguchi, Zachary M. Hudson

JOURNAL OF ORGANIC CHEMISTRY Vol. 85 ( 1 ) page： 108 - 117 2020.1

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

An N-phenylbenzimidazole constrained in a coplanar fashion with a methylene tether (IMAC) was designed and used to prepare a series of emitters exhibiting thermally activated delayed fluorescence (TADF). Four novel TADF emitters using 9,9-dimethylacridine, phenoxazine, phenothiazine, and bis(di-ptolylamino)carbazole as the donor group were designed and synthesized using IMAC as the acceptor. Additionally, two deepblue fluorescent emitters were prepared with carbazole and tercarbazole as the donor moieties. The twisted conformation between donor and acceptor in these molecules resulted in effective spatial separation of the HOMO and LUMO and small singlet-triplet energy gaps. Crystallographic properties, electronic structures, thermal stabilities, photophysical properties, and energy levels were studied systematically. Ultimately, these findings provide a promising opportunity for the design and synthesis of highly efficient TADF materials based on IMAC derivatives.

DOI： 10.1021/acs.joc.9b02283

Hydrophobicity and CH/pi-interaction-driven self-assembly of amphiphilic aromatic hydrocarbons into nanosheets Reviewed

Tsuyoshi Nishikawa, Hiroki Narita, Soichiro Ogi, Yoshikatsu Sato, Shigehiro Yamaguchi

CHEMICAL COMMUNICATIONS Vol. 55 ( 99 ) page： 14950 - 14953 2019.12

Language：English Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

The hydrophobicity and CH/pi-interaction-driven self-assembly of an amphiphile that contains a biphenylanthracene group furnishes two-dimensional aggregates in dilute aqueous solution. A windmill-shaped molecular packing structure that arises from multiple intermolecular CH/pi interactions of the aromatic hydrocarbons is the key motif for the self-assembly into micrometer-scale nanosheets.

DOI： 10.1039/c9cc08070h

[eta(5)-Cp*B-Mes](+): A Masked Potent Boron Lewis Acid

Hsi-Ching Tseng, Chao-Tang Shen, Kentaro Matsumoto, Ding-Nan Shih, Yi-Hung Liu, Shie-Ming Peng, Shigehiro Yamaguchi, Ya-Fan Lin, Ching-Wen Chiu

ORGANOMETALLICS Vol. 38 ( 22 ) page： 4516 - 4521 2019.11

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：AMER CHEMICAL SOC

The chemistry of the boron cation has been revitalized in the past decade due to its newfound application in stoichiometric and catalytic organic reactions. To extend the frontier of boron cation catalysis, we came to discover that a mesityl-substituted eta(5)-Cp*-coordinated boron cation could serve as a powerful Lewis acid for organic catalytic transformations. The boron cation [Cp*B-Mes][B(C6F5)(4)] ([1] [B(C6F5)(4)]) stabilized in a boronium-like electronic structure binds to Et3PO readily and displays an acceptor number exceeding that of B(C6F5)(3) on the Gutmann-Beckett acidity scale. The steric and electronic stabilization exerted by the electron-donating Cp* renders the highly Lewis acidic boron cation an easy-to-handle catalyst for hydrodeoxygenation of aryl ketones at ambient temperature. The exceptional catalytic performance of [1](+) implies that the incorporation of a coordinatively flexible substituent at boron is critical in bringing catalytic activity and stability to boron cation catalysts.

DOI： 10.1021/acs.organomet.9b00671

The Effect of Branching on the One- and Two-Photon Absorption, Cell Viability, and Localization of Cationic Triarylborane Chromophores with Dipolar versus Octupolar Charge Distributions for Cellular Imaging Reviewed

Stefanie Griesbeck, Evripidis Michail, Florian Rauch, Hiroaki Ogasawara, Chenguang Wang, Yoshikatsu Sato, Robert M. Edkins, Zuolun Zhang, Masayasu Taki, Christoph Lambert, Shigehiro Yamaguchi, Todd B. Marder

CHEMISTRY-A EUROPEAN JOURNAL Vol. 25 ( 57 ) page： 13164 - 13175 2019.10

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

Two different chromophores, namely a dipolar and an octupolar system, were prepared and their linear and nonlinear optical properties as well as their bioimaging capabilities were compared. Both contain triphenylamine as the donor and a triarylborane as the acceptor, the latter modified with cationic trimethylammonio groups to provide solubility in aqueous media. The octupolar system exhibits a much higher two-photon brightness, and also better cell viability and enhanced selectivity for lysosomes compared with the dipolar chromophore. Furthermore, both dyes were applied in two-photon excited fluorescence (TPEF) live-cell imaging.

DOI： 10.1002/chem.201902461

Near-infrared fluorescein dyes containing a tricoordinate boron atom

Naoki Ando, Hiroki Soutome, Shigehiro Yamaguchi

CHEMICAL SCIENCE Vol. 10 ( 33 ) page： 7816 - 7821 2019.9

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

Bora-fluoresceins (BFs), fluorescein analogues containing a tricoordinate boron atom instead of an oxygen atom at the 10-position of the fluorescein skeleton, were synthesized as a new family of fluorescein analogues. The deprotonated BFs exhibited absorption and fluorescence in the near-infrared region, which were significantly red-shifted relative to those of hitherto-known heteroatom-substituted fluorescein analogues on account of the orbital interaction between the tricoordinate boron atom and the fluorescein skeleton. BFs also showed multi-stage changes resulting from a Lewis acid-base equilibrium at the boron center in combination with a Bronsted acid-base equilibrium at the phenolic hydroxy group.

DOI： 10.1039/c9sc02314c

Monitoring Fluorescence Response of Amphiphilic Flapping Molecules in Compressed Monolayers at the Air-Water Interface Reviewed

Waka Nakanishi, Shohei Saito, Naoki Sakamoto, Akihiro Kashiwagi, Shigehiro Yamaguchi, Hideki Sakai, Katsuhiko Ariga

CHEMISTRY-AN ASIAN JOURNAL Vol. 14 ( 16 ) page： 2869 - 2876 2019.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

The air-water interface, which is the boundary of two phases with a large difference in polarity, gives a distinct environment compared with bulk water or air. Since the interface provides a field for various biomolecules to work, it is important to understand the molecular behaviors at the interface. Here, polarity-independent flapping viscosity probes (FLAP) equipped with hydrophobic/hydrophilic substituents have been synthesized and studied at the air-water interface. In situ fluorescence (FL), which is related to the internal motion and orientation, of three different FLAPs were investigated at the interface, and the internal motion of the molecule was indicated to be suppressed at the interface. In addition, the molecular response was compared with that of conventional viscosity probes (molecular rotors), which indicates the different behaviors of FLAP probably due to the distinct molecular orientation as well as molecular motion.

DOI： 10.1002/asia.201900769

A photostable fluorescent marker for the superresolution live imaging of the dynamic structure of the mitochondrial cristae Reviewed International journal

Chenguang Wang, Masayasu Taki, Yoshikatsu Sato, Yasushi Tamura, Hideyuki Yaginuma, Yasushi Okada, Shigehiro Yamaguchi

PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Vol. 116 ( 32 ) page： 15817 - 15822 2019.8

Language：English Publishing type：Research paper (scientific journal) Publisher：NATL ACAD SCIENCES

Stimulation emission depletion (STED) microscopy enables ultrastructural imaging of organelle dynamics with a high spatiotemporal resolution in living cells. For the visualization of the mitochondria! membrane dynamics in STED microscopy, rationally designed mitochondrial fluorescent markers with enhanced photostability are required. Herein, we report the development of a superphotostable fluorescent labeling reagent with long fluorescence lifetime, whose design is based on a structurally reinforced naphthophosphole fluorophore that is conjugated with an electron-donating diphenylamino group. The combination of long-lived fluorescence and superphotostable features of the fluorophore allowed us to selectively capture the ultrastructures of the mitochondria! cristae with a resolution of similar to 60 nm when depleted at 660 nm. This chemical tool provides morphological information of the cristae, which has so far only been observed in fixed cells using electron microscopy. Moreover, this method gives information about the dynamic ultrastructures such as the intermembrane fusion in different mitochondria as well as the intercristae mergence in a single mitochondrion during the apoptosis-like mitochondrial swelling process.

DOI： 10.1073/pnas.1905924116

Structurally Constrained Boron-, Nitrogen-, Silicon-, and Phosphorus-Centered Polycyclic pi-Conjugated Systems

Masato Hirai, Naoki Tanaka, Mika Sakai, Shigehiro Yamaguchi

CHEMICAL REVIEWS Vol. 119 ( 14 ) page： 8291 - 8331 2019.7

Language：Japanese Publisher：AMER CHEMICAL SOC

Incorporation of main group elements into the it-conjugated frameworks is a sophisticated strategy to alter the fundamental nature of the parent conjugated pi systems, giving rise to attractive electronic and photophysical properties that are otherwise inaccessible with classic carbon- or metal-based materials. Out of all irconjugated heterocycles, those that are structurally constrained by tethered aryl substituents surrounding the main group center deserve a great deal of attention because not only do they commonly possess the maximum efficiency of it -conjugation and intermolecular interaction, but they also enjoy remarkable thermal and morphological stabilities that are especially crucial for solid-state performances. In certain cases, elucidation of the behavior of such compounds may additionally provide sufficient perspective toward graphene materials doped with main group elements, which are widely considered as potential next -generation optoelectronic materials. In this review, we will specifically focus on historical developments of structurally constrained polycyclic it -electron systems particularly of those with boron, nitrogen, silicon, or phosphorus atoms annulated directly into the center of 2r -conjugated systems.

DOI： 10.1021/acs.chemrev.8b00637

Planarized B,N-phenylated dibenzoazaborine with a carbazole substructure: electronic impact of the structural constraint

Mikinori Ando, Mika Sakai, Naoki Ando, Masato Hirai, Shigehiro Yamaguchi

ORGANIC & BIOMOLECULAR CHEMISTRY Vol. 17 ( 22 ) page： 5500 - 5504 2019.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：ROYAL SOC CHEMISTRY

A B,N-diphenyl-5,10-dihydro-dibenzo-1,4-azaborine, in which both phenyl groups on the boron and nitrogen atoms are planarized to generate a carbazole substructure, was synthesized. The structral constraint around the boron and nitrogen atoms alters the pi-conjugation mode and thus the photophysical and electrochemical properties. Specifically, this structurally constrained dibenzoazaborine showed an intense blue emission with a narrow full width at half maximum. One of its derivatives exhibited near infrared absorption in the one-electron-oxidized state.

DOI： 10.1039/c9ob00934e

Optimization of Aqueous Stability versus pi-Conjugation in Tetracationic Bis(triarylborane) Chromophores: Applications in Live-Cell Fluorescence Imaging

Stefanie Griesbeck, Matthias Ferger, Corinna Czernetzi, Chenguang Wang, Ruediger Bertermann, Alexandra Friedrich, Martin Haehnel, Daniel Sieh, Masayasu Taki, Shigehiro Yamaguchi, Todd B. Marder

CHEMISTRY-A EUROPEAN JOURNAL Vol. 25 ( 32 ) page： 7679 - 7688 2019.6

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

The stability of tetracationic triarylboranes in dilute aqueous solution was investigated by tuning the steric demand of the linker in a (para-(N,N,N-trimethylammonio)xylyl)(2)B-(linker)-B(para-(N,N,N-trimethylammonio)xylyl)(2) structure. With increasing steric bulk of the linker, namely 1,4-phenylene, 2,2 '''-(3,3 '''-dimethyl)-5,2 ':5 ',2 '':5 '',5 '''-quaterthiophene, 9,10-anthracenylene, and 4,4 '''-(5 '-(3,5-dimethylphenyl))(5 ''-(3 ''',5 '''-dimethylphenyl))-2 ',2 ''-bithiophene, the stability of the compounds increased. The anthracene-based chromophore, compound 3M is water-stable for at least 48 h, is nontoxic to cells and exhibits an exceedingly high fluorescence quantum yield of 0.86 in water making it an ideal candidate for confocal live-cell imaging of lysosomes.

DOI： 10.1002/chem.201900723

Tuning the pi-bridge of quadrupolar triarylborane chromophores for one- and two-photon excited fluorescence imaging of lysosomes in live cells

Griesbeck Stefanie, Michail Evripidis, Wang Chenguang, Ogasawara Hiroaki, Lorenzen Sabine, Gerstner Lukas, Zang Theresa, Nitsch Joern, Sato Yoshikatsu, Bertermann Ruediger, Taki Masayasu, Lambert Christoph, Yamaguchi Shigehiro, Marder Todd B.

CHEMICAL SCIENCE Vol. 10 ( 20 ) page： 5405 - 5422 2019.5

Seeded Polymerization of an Amide-Functionalized Diketopyrrolopyrrole Dye in Aqueous Media

Soichiro Ogi, Natsumi Fukaya, Arifin, Bastian Bjerkem Skjelstad, Yuh Hijikata, Shigehiro Yamaguchi

CHEMISTRY-A EUROPEAN JOURNAL Vol. 25 ( 30 ) page： 7303 - 7307 2019.5

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

The self-assembly of an amide-functionalized dithienyldiketopyrrolopyrrole (DPP) dye in aqueous media was achieved through seed-initiated supramolecular polymerization. Temperature- and time-dependent studies showed that the spontaneous polymerization of the DPP derivative was temporally delayed upon cooling the monomer solution in a methanol/water mixture. Theoretical calculations revealed that an amide-functionalized DPP derivative adopts an energetically favorable folded conformation in the presence of water molecules due to hydration. This conformational change is most likely responsible for the trapping of monomers in the initial stage of the cooperative supramolecular polymerization in aqueous media. However, the monomeric species can selectively interact with externally added fragmented aggregates as seeds through concerted pi-stacking and hydrogen-bonding interactions. Consequently, the time course of the supramolecular polymerization and the morphology of the aggregated state can be controlled, and one-dimensional fibers that exhibit a J-aggregate-like bathochromically shifted absorption band can be obtained.

DOI： 10.1002/chem.201901382

Organic Letters 2.0: A New Beginning

Erick M. Carreira, Kuiling Ding, Margaret Brimble, Hung-wen Liu, Pauline Chiu, Nuno Maulide, Kavirayani R. Prasad, Zhenfeng Xi, Sarah E. Reisman, Shigehiro Yamaguchi, Tobias Ritter, Jin-Quan Yu

ORGANIC LETTERS Vol. 21 ( 1 ) page： 1 - 4 2019.1

Negative fluorescence anisotropy of phosphole oxide-based dyes in nematic liquid crystals Reviewed

Takuya Ohzono, Tetsuo Yatabe, Chenguang Wang, Aiko Fukazawa, Shigehiro Yamaguchi

COMMUNICATIONS CHEMISTRY Vol. 1 page： 52 2018.9

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：NATURE PUBLISHING GROUP

It is important to understand how solute molecules align in anisotropic media such as liquid crystals and biological membranes. Alignment of fluorescent probes used in polarised fluorescence microscopy is of interest because anisotropy of the medium is indirectly estimated through the fluorescence intensity originating from the transition dipole moments fixed on the molecule. Here we report fluorescence anisotropies of a series of phosphole oxide-based dyes with an elongated pi-conjugated system, along which the transition dipole moment lies, in nematic liquid crystals. We observe that as the number, size and rigidity of substituents protruding from the pi-conjugated plane increase, the transition dipole moment tends to tilt away from the nematic director over the magic angle, similar to 54.7 degrees, showing conspicuous negative fluorescence anisotropy. Analysis of molecular shapes suggests that the substitutions modulate the interaction with the nematic mean field, impacting the direction of the principal molecular axis aligned with the nematic director.

DOI： 10.1038/s42004-018-0055-6

Phosphorus-containing fluorophores for bio-imaging

Yamaguchi Shigehiro

ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY Vol. 256 2018.8

End-Capping pi-Conjugated Systems with Medium-Sized Sulfur-Containing Rings: A Route Towards Solution-Processable Air-Stable Semiconductors Reviewed

Aiko Fukazawa, Yusuke Toda, Masahiro Hayakawa, Anna Sekioka, Hiroyuki Ishii, Toshihiro Okamoto, Jun Takeya, Yuh Hijikata, Shigehiro Yamaguchi

CHEMISTRY-A EUROPEAN JOURNAL Vol. 24 ( 44 ) page： 11503 - 11510 2018.8

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：WILEY-V C H VERLAG GMBH

The sulfur-containing nine-membered heterocycle thiacyclononene (TN) was evaluated as a new type of end-capping group for pi-conjugated systems. A systematic study on TN-capped -oligothiophenes (TNnTs; n=4-7) revealed that the capping with TN, which adopts a bent conformation, imparts the resulting oligothiophenes with drastically increased solubility at approximately 140 degrees C and high electrochemical stability, whereas the electronic structure remains virtually unperturbed. The even-numbered oligothiophenes TN4T and TN6T form characteristic offset herringbone-type packing structures on account of the steric repulsion between the TN rings and the presence of intermolecular nonbonding S center dot center dot center dot S interactions. This packing mode in combination with the high solubility enabled the solution-process fabrication of field-effect transistors based on TN6T, which exhibited a high performance without degradation even upon exposure to air.

DOI： 10.1002/chem.201802656

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