Publications by authors named "Tomoki Ogoshi"

As the number of chiral ring molecules in chiral polyrotaxane increases, the number of possible stereoisomers exponentially increases. Consequently, the selective synthesis of a specific stereoisomer becomes much more challenging. To address this problem, we co-crystallized poly(ethylene glycol) and a diastereomeric ring molecule, pillar[5]arene, in the solid state.

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  • Organic dyes are widely used but their leakage into the environment is a global issue due to toxicity and nonbiodegradability, prompting the need for effective removal technologies.
  • This article discusses the synthesis of highly fluorinated conjugated microporous polymers that show promising adsorption properties, with a surface area of up to 1063 m²/g for removing cationic organic dyes from water.
  • The fluorinated polymers demonstrate a strong adsorption capacity of 313 mg/g for crystal violet, outperforming traditional adsorbents and also function as proton channels in lipid membranes.
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Supramolecular polymerization using two-dimensional π-conjugated chiral monomers has been mainly demonstrated because the supramolecular polymerization can be controlled by stereocommunication through π-π stacking between the two-dimensional chiral monomers. We herein report supramolecular copolymerization utilizing three-dimensional pentahedrons with twisted helical chirality through different combinations of helical-chiral acidic and basic pillar[5]arenes as comonomers. In this case, helical-sense matching is key to facilitating the supramolecular copolymerization.

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Metabolic abnormalities play a pivotal role in various pathological conditions, necessitating the quantification of specific metabolites for diagnosis. While mass spectrometry remains the primary method for metabolite measurement, its limited throughput underscores the need for biosensors capable of rapid detection. Previously, we reported that pillar[6]arene with 12 carboxylate groups (P6AC) forms host-guest complexes with 1-methylnicotinamide (1-MNA), which is produced in vivo by nicotinamide -methyltransferase (NNMT).

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  • Organic molecules can be chiral even without stereogenic carbon centers if they have high energy barriers for conformational changes.
  • The study analyzes the conformational behaviors of tricyclic propellane structures with 6-membered-ring groups attached to aromatic rings, revealing distinct properties between them.
  • The trinaphtho[3.3.3]propellane has no torsion and maintains stability while hexabenzo[4.4.4]propellane exhibits a significant twist with high activation energy, whereas the hybrid [4.3.3]propellane can quickly switch between twisted forms at low temperatures.
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  • Macrocyclic molecules like pillar[5]arenes exhibit unique properties such as high symmetry and the ability to trap guest molecules, which differs from linear compounds.
  • This study successfully introduced ten six-membered aromatic rings into pillar[5]arene, creating a stable cylindrical crystal structure while avoiding the complexities observed in previous variants with five-membered rings.
  • A significant increase in the dihedral angles between the core and outer benzene rings (from 38° to 66°) highlights the role of steric repulsion in shaping the structure and properties of these macrocyclic compounds.
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Self-inclusion complexes consisting of host-guest conjugates are one of the unique supramolecular structures because they form in-state and out-state depending on the external stimuli. Despite many reports of the stimuli-responsive self-inclusion complex formation, study of the structural relaxation from out-state to in-state by photoexcitation has been unexplored. Herein, we report that an electron-donating host and an electron-accepting guest conjugate exhibits the structural relaxation from out-state to in-state by photoexcitation.

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  • - Each nucleosome is made up of four types of histone proteins, and their tails are vital for regulating gene expression through modifications after protein synthesis (PTMs).
  • - Using high-speed atomic force microscopy, researchers studied nucleosome dynamics when histone tails were removed, finding that the absence of all tails caused significant structural changes and increased flexibility in nucleosome behavior.
  • - The study revealed that histone tails, especially from H2B and H3, stabilize nucleosomes and their post-translational modifications play a key role in how nucleosomes interact with DNA.
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We present a novel system, a liquid-state pillar[5]arene decorated with tri(ethylene oxide) chains, that brings electron-donor and electron-acceptor molecules into proximity for efficient exciplex formation. The electron-accepting guests exhibit a blue-purple emission from a localized excited state upon excitation in common solvents. However, directly dissolving the guests in the electron-donating pillar[5]arene liquid (a bulk system) results in visible green emission from the formed exciplexes.

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  • Macrocyclic arenes can adapt their shape to form complexes with specific guest molecules, but tend to have poor light emission in solid form due to self-absorption issues.* -
  • New derivatives of pillar[6]arene were synthesized, featuring a structure that alternates between methylene and nitrogen bridges, enhancing their light-emission properties by improving charge transfer dynamics.* -
  • One of these new nitrogen-containing pillar[6]arenes exhibits a high photoluminescence quantum yield and can detect nitrobenzene vapor through a fluorescence quenching effect, forming non-emissive complexes upon exposure.*
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Solid-state assembling modes are as crucial as the chemical structures of single molecules for real applications. In this work, solid-state structures and phase-transition temperatures are investigated for a series of fluoranthene-fused [3.3.

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  • Methylene-bridged macrocyclic arenes have limitations in electronic conjugation due to disrupted π orbital communication, affecting their use in supramolecular chemistry.
  • A series of silapillar[]arenes were synthesized using silylene bridging, showing improved electronic properties through σ*-π* conjugation, enhancing their performance compared to traditional pillar[]arenes.
  • The introduction of silylene-bridging increases structural flexibility and leads to unique size-dependent structural and optical characteristics in silapillar[]arenes.
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  • Pillar[n]arenes can be made through a process called Friedel-Crafts alkylation, but this results in a mix of sizes, making purification hard for larger versions.
  • Using an irreversible Friedel-Crafts acylation instead allows for a more controlled production of these compounds, where the size of the pillar[n]arenes is directly linked to the length of the starting materials.
  • This method not only simplifies the creation process by avoiding unwanted side products, but it also enables the addition of reactive carbonyl groups on the bridges, leading to new functionalized structures that aren’t possible with the alkylation method.
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Artificial water channels (AWCs) that selectively transport water and reject ions through bilayer membranes have potential to act as synthetic Aquaporins (AQPs). AWCs can have a similar osmotic permeability, better stability, with simpler manufacture on a larger-scale and have higher functional density and surface permeability when inserted into the membrane. Here, we report the screening of combinatorial libraries of symmetrical and unsymmetrical rim-functionalized PAs A-D that are able to transport ca.

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  • Pillar[n]arenes are macrocyclic compounds made of benzene panels linked by methylene groups, known for their chirality and ability to form optically active materials.
  • Their dynamic chirality allows them to interact with chiral guests and respond to environmental changes, making them useful in chiroptical applications.
  • By incorporating additional chiral structures, these compounds can also act as molecular sensors that detect not only chiral guests but also signals from achiral substances.
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  • - Chiral rotaxanes, known for their unique interlocked structures, have gained interest for their chirality, prompting the development of selective synthesis methods, particularly focusing on creating diastereomers through chiral substituents.
  • - The new synthesis approach presented hinges on solid-phase diastereoselective formation of [3]pseudorotaxanes, allowing for a 92% diastereomeric excess due to enhanced effective molarity and larger energy differences between the diastereomers in a solid state.
  • - In contrast, the synthesis in solution only achieved a 10% diastereomeric excess due to closer energy levels between diastereomers; however, solid-phase reactions successfully produced rot
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Ca/calmodulin-dependent protein kinase II (CaMKII) plays a pivotal role in synaptic plasticity. It is a dodecameric serine/threonine kinase that has been highly conserved across metazoans for over a million years. Despite the extensive knowledge of the mechanisms underlying CaMKII activation, its behavior at the molecular level has remained unobserved.

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A three-dimensional skeleton, π-fused [4.3.3]propellane, was constructed and derivatized by selective π-extension at the two naphthalene units.

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  • Chirality of host molecules can change based on the guest molecules, but adapting the chirality of hosts to -alkane lengths is difficult due to -alkanes being neutral and linear.
  • A new pillar[5]arene-based macrocyclic host was developed, which has five stereogenic carbons and responds to the lengths of complexed -alkanes, leading to changes in its chirality.
  • Experimental results and theoretical analyses suggest that short -alkanes prefer a certain chirality form at lower temperatures, while longer -alkanes favor a different form, showing that temperature affects the adaptive chirality of the host.
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Invited for the cover of this issue is the group of Hiromu Kashida and Hiroyuki Asanuma at Nagoya University and co-workers. The image depicts the orientation dependence of circularly polarized luminescent. Read the full text of the article at 10.

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Installation of various substituents is a reliable and versatile way to alter the properties of macrocyclic molecules, but high-yield and controlled methods are not always available especially for multifold reactions. Herein, we report 10- and 12-fold introduction of aryl substituents onto both rims of cylinder-shaped pillar[]arenes, which usually have alkoxy substituents slanting to the cylinder axes. Although alkoxy pillar[5]arenes exist as -symmetric enantiomeric pairs, arylated pillar[5]arenes provide crushed single-crystal structures and stereoisomerism including -symmetric conformations depending on the aryl groups.

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Controlling dynamic chirality and memorizing the controlled chirality are important. Chirality memory has mainly been achieved using noncovalent interactions. However, in many cases, the memorized chirality arising from noncovalent interactions is erased by changing the conditions such as the solvent and temperature.

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We have investigated the chiroptical activities of pyrene clusters incorporated within a DNA duplex. Three pyrene derivatives were prepared on d-threoninol linkers to allow incorporation within a DNA strand. DNA scaffolds containing dimers, tetramers, and hexamers of the pyrene derivatives were prepared.

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