Chemistry Letters
Online ISSN : 1348-0715
Print ISSN : 0366-7022
ISSN-L : 0366-7022
Volume 50 , Issue 6
Showing 1-39 articles out of 39 articles from the selected issue
Letter
Vol. 50 Commemorative Highlight Review
  • Pallabi Sinha Roy, Gil Garnier, Florent Allais, Kei Saito
    2021 Volume 50 Issue 6 Pages 1123-1130
    Published: June 05, 2021
    Released: June 17, 2021
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    Considering the drawbacks associated with fossil-based molecules, polymers and materials, lignin has acquired immense popularity owing to its distinct advantages. However, to date it has not been widely commercialized to produce fossil replacements mainly due to its complex structure and purification hassle. Constant research is going on to discover ways to depolymerize lignin to produce various aromatic chemicals. This highlight review summarizes the key investigations carried out in the field of lignin valorization, purification and the valuable products generated from lignin.

    This review covers a brief discussion about the advantages and challenges associated with the current lignin depolymerization technologies, their separation techniques and the promising end-use applications of the lignin-derived compounds. Fullsize Image
     
  • Yoshitane Imai
    2021 Volume 50 Issue 6 Pages 1131-1141
    Published: June 05, 2021
    Released: June 17, 2021
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    Circularly polarized luminescence (CPL) has attracted significant attention in the fields of chiral photonics and optoelectronic materials science. In a CPL-emitting system, a chiral luminophore derived from chiral molecules is usually essential, and a pair of enantiomeric luminophores is indispensable for the typical selective-emission of right- and left-handed CPL. This review focuses on non-classical CPL systems that do not use pairs of enantiomers and introduces symmetry-breaking CPL systems that do not use optically active molecules, and covers photoexcited chiral-switching, spontaneous-resolution, cryptochirality, and magnetic CPL.

    Non-classical circularly polarized luminescence (NC-CPL) system is a method that uses no pair of enantiomeric molecules and symmetrybreaking CPL (SB-CPL) system is a method that uses no optically active molecules. These NC-CPL and SB-CPL systems produce photoexcited chiral-switching, spontaneous-resolution, cryptochiral, and magnetic CPL. Fullsize Image
     
Letter
  • Mayuko Fujitsuka, Kouta Araki, Tatsuhiro Kodama, Tran Thi Dieu Hien, M ...
    2021 Volume 50 Issue 6 Pages 1142-1145
    Published: June 05, 2021
    Released: June 17, 2021
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    The synthesis of biocompatible nanomaterials from synthetic organic molecules, as well as the spin state switching of spin crossover complexes, are presently of interest. However, in the case of labile Fe2+ complexes, it is challenging to induce dynamic transitions using supramolecular strategies. In the present work, highly organized structures made of glycyrrhetinic acid polyglycosides induced equilibrium between low and high spin states in an [Fe(TACN)2]2+ complex. Hybrids composed of these polyglycosides with this complex exhibited nanostructures such as nanosheets in addition to spin crossover phenomena and changes in oxidation state. Glycyrrhetinic acid polyglycoside derivatives also demonstrated an extremely low degree of change in spin crossover and resistance to oxidation state changes. The present technique of combining naturally occurring molecules with discrete coordination complexes is expected to allow the design of flexible, stimuli-responsive supramolecular coordination systems.

Vol. 50 Commemorative Highlight Review
  • Satoru Hiroto
    2021 Volume 50 Issue 6 Pages 1146-1155
    Published: June 05, 2021
    Released: June 17, 2021
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    Nowadays, exploring the chemistry of curved π-conjugated molecules is one of the big trends in organic chemistry. Recently, research interests have been shifted to heteroatom containing analogs. Among these, bowl-shaped π-conjugated molecules with heteroatoms included within their skeletons have gained interest due to their synthetic difficulty and have been developed dramatically as a motif for heteroatom-doped carbon materials. Here, this review highlights analogs based on polycyclic aromatic hydrocarbons, represented by triangulenes, sumanenes and corannulenes, with heteroatoms. These studies have disclosed the effect of heteroatoms in curved π-surfaces.

    Nowadays, chemistry of curved π-conjugated molecules is one of the big trends in organic chemistry. Among these, bowl-shaped π-conjugated molecules containing heteroatoms have gained interest due to their synthetic difficulty and as a motif for heteroatom-doped carbon materials. This review highlights the analogs based on polycyclic aromatic hydrocarbons with heteroatoms. These researches have disclosed the effect of heteroatoms in curved π-surface. Fullsize Image
     
Letter
Vol. 50 Commemorative Highlight Review
  • Tomohiro Hayashi
    2021 Volume 50 Issue 6 Pages 1173-1180
    Published: June 05, 2021
    Released: June 17, 2021
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    Water at interfaces plays essential roles in many natural phenomena and engineering applications. However, the molecular behavior of interfacial water is still a matter of intense debate. Thus far, many experimental and theoretical methods have been employed to elucidate the real picture (structure, dynamics, hydrogen bonding states, etc.) of interfacial water and its relevance to interfacial phenomena and material functions. The author reviews these works and discusses the principles and limitations of the analytical methods. The significant representative findings on water-mediated interfacial phenomena are also introduced.

    In this review, the author introduces experimental and theoretical approaches to investigate water at interfaces. The principles and their limitations, and essential findings in this field are also discussed. Fullsize Image
     
Letter
Vol. 50 Commemorative Highlight Review
  • Soumyakanta Prusty, Yi-Tsu Chan
    2021 Volume 50 Issue 6 Pages 1202-1212
    Published: June 05, 2021
    Released: June 17, 2021
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    Coordination-driven self-assembly of metal ions and organic ligands has been extensively applied over the past few decades, towards construction of various functional two-dimensional (2D) and three-dimensional (3D) architectures. The majority of these structures are homoleptic in nature, consisting of one type of ligand. However, the functionality of self-assembled complexes can be potentially increased by increasing their complexity. To address this, recent efforts have been concentrated on synthesis of heteroleptic complexes composed of more than one type of ligand. This review article highlights the recent developments of 2,2′:6′,2′′-terpyridine (tpy)-based self-assembled heteroleptic coordination complexes. The first part of this review collects examples of heteroleptic tpy complexes constructed in a stepwise manner with metalloligands as primary components, and the one-pot strategies are described in the second part.

    Coordination-driven self-assembly has been widely used in construction of various functional two- and three-dimensional architectures. The functionality of self-assembled complexes can be potentially increased by increasing their complexity. Hence, the substantial efforts have been devoted to preparing heteroleptic complexes composed of more than one type of ligand. This review article highlights the recent developments of 2,2':6',2''-terpyridine (tpy)-based heteroleptic complexes. Fullsize Image
     
Letter
Editor's Choice
  • Sota Kato, Daisuke Aoki, Hideyuki Otsuka
    2021 Volume 50 Issue 6 Pages 1223-1225
    Published: June 05, 2021
    Released: June 17, 2021
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    In solvent freezing, polyurethane gels cross-linked with tetraarylsuccinonitrile (TASN) moieties which can be cleaved to afford pink-colored and yellow-fluorescent radicals by mechanical stress, show mechano-activated fluorescence based on dissociated TASN radicals and provide a consistent reaction field with vinyl monomers. We herein propose a toughening of a polymer network via freezing-induced mechanochemistry. Through the consistent reaction field, the toughness of resulting polymer networks can be changed by the number of repeated freeze-thaw cycles and the concentration of dissociated TASN radicals.

Vol. 50 Commemorative Highlight Review
  • Yuichiro Nishizawa, Kenshiro Honda, Daisuke Suzuki
    2021 Volume 50 Issue 6 Pages 1226-1235
    Published: June 05, 2021
    Released: June 17, 2021
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    Hydrogel microspheres (microgels) are water-swollen, soft colloidal particles composed of cross-linked hydrophilic or amphiphilic polymer chains. Due to their fascinating properties such as biocompatibility, colloidal stability, and rapid stimulus responsivity, microgels are expected to find numerous applications in a wide variety of fields. The understanding and development of microgels with colloidal-sized dimensions has been propelled in particular by visualization techniques. Their history and recent progress in microgel evaluation using such visualization techniques are summarized in this review.

    Hydrogel microspheres (microgels) are water-swollen, soft colloidal particles composed of cross-linked hydrophilic or amphiphilic polymer chains. The understanding and development of microgels with colloidal-sized dimensions has been propelled in particular by visualization techniques. Their history and recent progress in microgel evaluation using such visualization techniques are summarized in this review. Fullsize Image
     
Letter
Vol. 50 Commemorative Highlight Review
  • Hiromi Takahashi, Takao Yasui, Yoshinobu Baba
    2021 Volume 50 Issue 6 Pages 1244-1253
    Published: June 05, 2021
    Released: June 17, 2021
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    Methods that can rapidly and accurately extract or isolate nucleic acids would facilitate the capability for scientists to access key information regarding nucleic acid molecular signatures. Knowing these molecular signatures could contribute to development of strategies for detecting, treating, and diagnosing diseases based on nucleic acids. However, major impediments to accessing nucleic acids are their natural characteristics, including concentration and size. Here we review the development of nanomaterial-based devices to isolate circulating nucleic acids from biological samples, including blood, urine, cell, and virus; these devices enable enhancement of isolation and extraction efficiency compared to conventional methods.

    In this review, we summarize the recent development of nanomaterial-based devices to isolate circulating nucleic acids from biological samples, including blood, urine, cell, and virus as powerful alternatives to conventional tools, which would facilitate the capability for scientists to access key information regarding the nucleic acid molecular signatures used in molecular diagnostic. Fullsize Image
     
Letter
Vol. 50 Commemorative Highlight Review
  • Yoshinori Yamanoi, Toyotaka Nakae, Hiroshi Nishihara
    2021 Volume 50 Issue 6 Pages 1263-1270
    Published: June 05, 2021
    Released: June 17, 2021
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    This review discusses methods for increasing the efficiency of photoelectric conversion systems using photosystem I (PSI) and photosystem II (PSII) isolated from thermophilic cyanobacteria. The structure and electron transfer pathways for PSI and PSII are described, followed by a description of a new type of photoelectric conversion system and its application in light-sensing devices using PSI or PSII. Photoelectron transfer is demonstrated by spectroscopic and electrochemical measurements. A strategy to enhance photocurrent intensity is described, involving wiring photosynthetic reaction centers onto a self-assembled monolayer on an electrode. We review the fundamental concept behind these semi-artificial photosynthetic systems, as well as representative examples from published papers, including those from our laboratory.

    This review discusses methods for increasing the efficiency of photoelectric conversion systems using photosystem I (PSI) and photosystem II (PSII) isolated from thermophilic cyanobacteria. Fabrication of photoelectric conversion systems and their applications in light-sensing devices using PSI or PSII are described. A strategy to enhance photocurrent intensity is also described, involving wiring photosynthetic reaction centers onto a self-assembled monolayer on an electrode. Fullsize Image
     
Letter
  • Yuki Yoshihara, Shintaro Fujii, Shuhei Higashibayashi, Manabu Kiguchi, ...
    2021 Volume 50 Issue 6 Pages 1271-1273
    Published: June 05, 2021
    Released: June 17, 2021
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    Electric switches are one of the most fundamental electric circuitries. Recent developments in single-molecule techniques allow us to study various electric-switching phenomena on the single-molecule scale. In this study, the switch of the current through a single molecule of a biphenothiazine derivative was investigated using the break junction technique. The biphenothiazine derivative undergoes acid-base reaction-induced electronic modulation due to the reversible structural transformation between a closed shell and an open shell, resulting in a change in the electronic gap and effective tunneling barrier height. We succeeded in controlling the single-molecule electric conductivity of the biphenothiazine derivative wired to two Au electrodes by allowing the reaction to proceed reversibly on the electrode.

  • Shinichiro Kano, Yui Tsunekawa, Syuji Fujii, Yoshinobu Nakamura, Shin- ...
    2021 Volume 50 Issue 6 Pages 1274-1277
    Published: June 05, 2021
    Released: June 17, 2021
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    Liquid marble (LM) can be prepared by the adsorption of hydrophobic powder on the gas–liquid interface of a water droplet. Generally, LM is prepared using hydrophobic powder with a size of >100 nm. LM is opaque and the inside of LMs cannot be observed because the surface powder adsorbs and scatters the visible light. In this study, a pH-responsive clear LM (CLM) is prepared using tertiary amino groups containing hydrophobic silica particles with a diameter of ∼20 nm. The shape of CLM changed under acidic conditions, because the tertiary amino groups on the silica particles became hydrophilic under these conditions.

  • China Okamoto, Atsuya Momotake, Masami Kobayashi, Yasuhiko Yamamoto
    2021 Volume 50 Issue 6 Pages 1278-1281
    Published: June 05, 2021
    Released: June 17, 2021
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    Pheophorbide a (Phed-a), a naturally occurring chlorophyll catabolite, has been receiving much attention as a biologically-derived photosensitizer in photodynamic therapy (PDT) because of its high phototoxicity even in anoxic environments. Interaction of phed-a with G-quadruplex DNAs possessing a variety of folding topologies has been investigated to elucidate the molecular recognition of G-quadruplex DNA by phed-a, which is crucial to determine its PDT efficacy in tumor hypoxia. We found that phed-a binds selectively to the 3′-terminal G-quartet of parallel G-quadruplex DNAs.

Vol. 50 Commemorative Highlight Review
Award Highlight Review
Letter
Vol. 50 Commemorative Highlight Review
  • Wataru Sugimoto, Daisuke Takimoto
    2021 Volume 50 Issue 6 Pages 1304-1312
    Published: June 05, 2021
    Released: June 17, 2021
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    Advancement in synthetic materials chemistry has brought about a new family of two-dimensional nanostructures (nanosheets) which have a variety of promising applications. In particular, synthesis of platinum group metal (PGM) oxide nanosheets such as RuO2 and IrO2 and PGM nanosheets (Pt, Ru, Rh, Pd, etc) have attracted researchers owing to the advantages of nanosheets versus nanoparticles, and the wide range of applications that PGM materials may realize. This highlight review will provide a summary of state-of-the-art PGM nanosheets and a critical assessment on the possible applications of the innovative nanomaterials.

    Nanosheets represent a new family of two-dimensional nanostructures with a variety of promising applications. Platinum group metal and metal oxide nanosheets have attracted particular interest owing to the advantageous contrasted with nanoparticles. Here, we will provide a summary of nanosheets based on platinum group metal and some conceivable applications of the innovative nanomaterials. Fullsize Image
     
  • Shinsuke Inuki, Hiroaki Ohno
    2021 Volume 50 Issue 6 Pages 1313-1324
    Published: June 05, 2021
    Released: June 17, 2021
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    Natural sphingosine analogues containing a β, β′-dihydroxy α-amino acid framework demonstrate potent antifungal or immunosuppressive activity and are potential candidates for the development of chemical tools or pharmaceuticals. This Highlight Review presents the total syntheses of sphingosine analogues, myriocin, mycestericins and sphingofungin E, focusing on the strategies used for stereoselective construction of the quaternary α-amino acid motif embedded in these sphingosine analogues. Various methods have been developed, including C–C/C–N bond formation and desymmetrization strategies, leading to the development of efficient and divergent synthetic routes.

    This Highlight Review sheds light on the total syntheses of myriocin, mycestericins and sphingofungin E, focusing on the strategies for stereoselective construction of the quaternary α-amino acid motifs embedded in these sphingosine analogues. Various methodologies have been developed, including the C-C/C-N bond formation and desymmetrization strategies. These efforts have led to the development of efficient and divergent synthetic routes to these sphingosine analogues. Fullsize Image
     
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