Article
Multidisciplinary Sciences
Lara E. Zetzsche, Jessica A. Yazarians, Suman Chakrabarty, Meagan E. Hinze, Lauren A. M. Murray, April L. Lukowski, Leo A. Joyce, Alison R. H. Narayan
Summary: This study demonstrates the use of cytochrome P450 enzymes for biocatalytic cross-coupling reactions, enabling the formation of sterically hindered biaryl bonds through oxidative C-C bond formation. By engineering the substrate and atroposelectivity of the P450 enzyme, a highly efficient and selective process has been developed.
Article
Crystallography
Hui Wang, Tong Shu, Jingyi Chen, Ying Guo
Summary: This study investigates the characteristics of water in channels of blue-green beryl and its impact on color. Through various analytical methods, it is found that the water molecules are correlated with the types of metal ions and related peak values, thus affecting the coloration of beryl.
Article
Spectroscopy
Smita Verma, Velayutham Ravichandiran, Nihar Ranjan
Summary: A selective fluorescence sensor for carbonate ions has been developed in this study, which can rapidly detect low concentrations of carbonate ions. Experimental results demonstrate direct interaction between the sensor and carbonate ions, with potential implications for disease prevention and toxicity assessment.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2021)
Article
Geochemistry & Geophysics
Hui Wang, Qiyun Guan, Yuchong Liu, Ying Guo
Summary: This study investigates the effect of transition metal ions on the color of blue-green beryl using industrial cameras and various characterization methods. The results show that the d-d transition and charge transfer of Fe3+ in its sixfold coordination can cause a yellow tone, while the charge transfer of Fe2+/Fe3+ with sixfold coordination results in a blue-green tone. Additionally, the chroma of blue-green beryl is negatively influenced by the ratio of Cs+Mn to Fe contents, and the lightness is negatively correlated with the total content of transition metal ions.
Article
Chemistry, Multidisciplinary
Jie Xu, Samantha Grosslight, Kyle A. Mack, Sierra C. Nguyen, Kyle Clagg, Ngiap-Kie Lim, Jacob C. Timmerman, Jeff Shen, Nicholas A. White, Lauren E. Sirois, Chong Han, Haiming Zhang, Matthew S. Sigman, Francis Gosselin
Summary: An efficient asymmetric synthesis of a potent KRAS G12C covalent inhibitor, GDC-6036, was reported. The synthesis involved a highly selective Negishi coupling and a series of reaction sequences, leading to the desired compound with a 40% overall yield from the starting materials.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Organic
Hasrat Ali, Brigitte Guerin, Johan E. van Lier
Summary: This study reveals that the introduction of substituents at different positions of the pyrrole ring in BODIPY derivatives has a significant impact on their spectroscopic properties, with compounds featuring electron donating substituents showing larger red shifts. Additionally, some compounds exhibit remarkable pH-responsive changes in absorption and fluorescence emission spectra during protonation.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Applied
Wenhua Lin, Liping Zhang, Yanping Ma, Tongling Liang, Wen-Hua Sun
Summary: The sterically hindered 2-iminopyridine derivatives and their palladium chlorides complexes efficiently catalyze the Suzuki-Miyaura coupling reaction in aqueous solution, with good substrate scope and reusability for multiple batches. The spontaneous separation of coupling products in the aqueous medium adds to the process's appeal, while the catalytic performance can be significantly influenced by UV irradiation due to the photoisomerization of the catalysts' azo units. Overall, these titled palladium complexes offer a green, sustainable, cost-effective, and convenient method for synthesizing SMC products at a multi-gram scale.
APPLIED ORGANOMETALLIC CHEMISTRY
(2022)
Article
Materials Science, Ceramics
Seema Thakur, Vanita Thakur, Anumeet Kaur, Lakhwant Singh
Summary: The structural and optical properties of bismuth barium titanate glass-ceramics were studied, revealing that an increase in BaTiO3 content led to enhanced network compactness and higher optical band gap energy. The electronic polarizability values indicated that the glass-ceramic samples exhibited covalent character.
JOURNAL OF NON-CRYSTALLINE SOLIDS
(2021)
Article
Chemistry, Physical
Pavol Tisovsky, Klaudia Csicsai, Jana Donovalova, Robert Sandrik, Jozef Kozisek, Anton Gaplovsky
Summary: Zn(II) complexes were synthesized using L-a and L-b, with the Z-isomers isolated from the reaction mixture. The structure of these complexes was determined by NMR spectroscopy and X-ray diffraction analysis. The Z-isomers of complexes can undergo changes in the hydrazo = azo equilibrium through light-stimulated photoreactions.
JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Tatjana Wall, Marko Leist, Fabian Dietrich, Werner R. Thiel, Markus Gerhards
Summary: A concept for quantifying cooperative effects in transition-metal complexes is demonstrated through a series of novel mono- and binuclear complexes based on a specific ligand. These complexes containing iridium, platinum, and palladium were studied for their absorption and fluorescence spectra, with a focus on electronic absorptions and energetic shifts between mononuclear and dinuclear complexes. Fluorescence spectra were also analyzed in relation to the concept of cooperativity.
Article
Chemistry, Physical
Paul O. Peterson, Matthew Joannou, Eric M. Simmons, Steven R. Wisniewski, Junho Kim, Paul J. Chirik
Summary: The synthesis and characterization of phenoxy(imine) iron(II) alkyl precatalysts for C(sp2)-C(sp3) Suzuki-Miyaura cross-coupling reaction is reported. This method utilizes mild alkoxide bases and nonpolar solvents to achieve high efficiency C(sp2)-C(sp3) bond formation with various aryl boronic esters and alkyl bromides. The study also highlights the compatibility of the precatalysts with base-sensitive functionality and the role of boronate intermediates in transmetalation.
Review
Agronomy
Andres Perez-San Martin, Frutos C. Marhuenda-Egea, Maria Angeles Bustamante, Gustavo Curaqueo
Summary: This review critically analyzes and updates the chemical spectroscopy methods for evaluating the transformation of organic matter in composting, and discusses their potential applications in optimizing compost quality for agricultural use.
Article
Nanoscience & Nanotechnology
Priya Karna, Micheal Okeke, Debora Motta Meira, Zou Finfrock, Dong-Sheng Yang
Summary: This research reports the formation of Pd-nanocluster catalysts and their involvement in ligand-free Suzuki-Miyaura reactions. The catalysts are formed by leaching spherical Pd(0) nanoparticles with an average diameter of about 3 nm, and they are soluble in water. The reduction of Pd(II) is induced by ethanol and enhanced by potassium hydroxide.
ACS APPLIED NANO MATERIALS
(2022)
Article
Chemistry, Multidisciplinary
Yan-Long Zheng, Pei-Pei Xie, Omid Daneshfar, Kendall N. Houk, Xin Hong, Stephen G. Newman
Summary: A new method has been developed to convert alkyl esters into alkyl ketones, resulting in the synthesis of 65 different alkyl ketones with various functional groups and heterocyclic structures. The study found that catalyst-controlled chemoselectivity could activate the C(acyl)-O bond in the substrate, while density functional theory calculations supported the mechanism of the nickel catalytic cycle.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Junyi Han, Yuta Uetake, Yumi Yakiyama, Hidehiro Sakurai
Summary: A series of sumanenetrione derivatives were synthesized via Lewis acid-mediated Suzuki-Miyaura cross-coupling. The optical properties of these derivatives showed the strong electron-accepting ability of sumanenetrione. The ring-opening response adjacent to the substituent in the 2-hydroxyphenyl derivative occurred even at room temperature without the need for any activation, which typically requires harsh conditions.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Tomohiko Nishiuchi, Kazuki Kisaka, Takashi Kubo
Summary: This study discusses the synthesis and properties of anthracene-based cyclic pi-clusters with two and four anthracene units. The optimal cyclization conditions were determined through a nickel-mediated reaction, resulting in a cyclic anthracene dimer as the major product. The cyclic anthracene dimer showed red-shifted absorption and multi-stimuli responsiveness, such as photoisomerization and mechanochromism.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Takuya Kodama, Mitsuya Aoba, Yasukazu Hirao, Samara Medina Rivero, Juan Casado, Takashi Kubo
Summary: This study reports the preparation and characterization of a through-space conjugated multi-phenalenyl triradical. The investigation shows that the triradical can exist in two forms- an acute form in solution state and a preferred obtuse form in solid state, and these two forms can be reversibly interconverted by thermal energy.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Tomohiko Nishiuchi, Daisuke Ishii, Seito Aibara, Hiroyasu Sato, Takashi Kubo
Summary: In this study, a highly stable TAntM radical was successfully synthesized using a TIPS-ethynyl group, which effectively suppresses the reactivity of the radical. Chemical modification of the radical can be performed at room temperature, making it a versatile strategy for constructing unique spin-labelled molecules.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Multidisciplinary
Tomohiko Nishiuchi, Hikaru Sotome, Kazuto Shimizu, Hiroshi Miyasaka, Takashi Kubo
Summary: In this study, 1,2,3-tri(9-anthryl)benzene derivatives containing three radially arranged anthracenes in a pi-cluster were synthesized using Negishi coupling. The unique electronic properties and excited-state dynamic behavior of these derivatives, such as exciton localization/delocalization, were investigated.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Physical
Yasukazu Hirao, Keiji Ihara, Yukihide Ishibashi, Elisha Gabrielle Tiu, Tsuyoshi Asahi, Takashi Kubo
Summary: The ground-state electronic structure and excited-state dynamics of a fluorene-endcapped butatriene were investigated, and the unique photoluminescence properties of tetraphenyl-endcapped butatrienes were elucidated.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Organic
Yasukazu Hirao, Hajime Eto, Mitsuru Teraoka, Takashi Kubo
Summary: A 1,4-dihydropyridine derivative with bulky aryl substituents and no carbonyl groups was synthesized and found to possess high hydride donating ability, acid resistance, and reusability. Thermodynamic parameters for electron and hydride transfer in the redox system were determined, and the compound was shown to promote efficient, selective reduction reactions under mild conditions.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Tomohiko Nishiuchi, Seito Aibara, Takuya Yamakado, Ryo Kimura, Shohei Saito, Hiroyasu Sato, Takashi Kubo
Summary: This article investigates the characteristics of overcrowded ethylenes composed of 10-methyleneanthrone and two bulky aromatic rings. The crystals of these ethylenes exhibit various colors in different solvents due to their unique conformational features. Experimental studies reveal the relationships between the colors and the twist angles, fold angles, and dihedral angles of the ethylenes. Moreover, these conformations can be influenced by mechanical, pressure, and thermal stimuli.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Yasukazu Hirao, Yosuke Hamamoto, Takashi Kubo
Summary: The introduction of linear alkoxy chains into bianthrone promotes the aggregation of minor twisted conformers and competes with major folded conformers in the solid-state. Heating powders of substituted derivatives leads to isomerization reactions and color changes, indicating the convergence of alkyl chains to different conformers. These reactions involve only conformational isomerization without pyrolysis, as confirmed by FT-IR spectroscopy and powder XRD. Crystal structure analysis shows that twisted conformers with longer alkyl chains are stabilized in the solid-state by hydrophobic interactions and pi-pi stacking interactions.
CHEMISTRY-AN ASIAN JOURNAL
(2022)
Article
Chemistry, Physical
Yasukazu Hirao, Honami Inobe, Katsuma Hosoi, Takashi Kubo
Summary: In this study, a dyad consisting of a modified anthranol with enhanced electron-donating ability and a modified acridine with enhanced electron-accepting ability was found to form crystal polymorphs with different colors and hydrogen-bonding motifs. Structural and spectroscopic analyses revealed that the crystals with unusual colors exhibited stronger intermolecular hydrogen bonding and a red-shifted, enhanced charge-transfer absorption band. The combined experimental and theoretical results suggest a synergistic effect between hydrogen bonding and charge transfer in these crystals.
JOURNAL OF PHYSICAL CHEMISTRY C
(2022)
Article
Chemistry, Multidisciplinary
Tomohiko Nishiuchi, Shino Takeuchi, Yuta Makihara, Ryo Kimura, Shohei Saito, Hiroyasu Sato, Takashi Kubo
Summary: A Negishi coupling based synthesis of 1,2,4,5-tetra(9-anthryl)benzene derivatives with X-shaped molecular structures is described. X-ray crystallographic analysis reveals that the two-dimensional highly ordered packing structure of the unsubstituted derivative is a result of intermolecular interactions between anthracene units. Photoirradiation of the unsubstituted derivative promotes intramolecular [4+4] photocycloaddition reactions, leading to the formation of a crystalline polycyclic product featuring a unique long carbon-carbon single bond. Additionally, charge-transfer complexes exhibiting near-infrared absorption and emission are formed by co-crystallization with electron acceptor molecules.
BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN
(2022)
Article
Chemistry, Multidisciplinary
Shinya Sugiura, Takashi Kubo, Yohei Haketa, Yuta Hori, Yasuteru Shigeta, Hayato Sakai, Taku Hasobe, Hiromitsu Maeda
Summary: Quinoidal molecules based on dipyrrolyldiketone boron complexes (QPBs) with partially conjugated pyrrole units as spin coupler were synthesized. The introduction of a benzo unit at the pyrrole beta-positions stabilized QPB, forming a closed-shell tautomer conformation with near-infrared absorption. By adding bases, the deprotonated species monoanion QPB- and dianion QPB2- were formed, showing over 1000 nm absorption and ion pairs with countercations. Ion-pairing with pi -electronic and aliphatic cations modulated the diradical properties of QPB2-, characterized by cation-dependent hyperfine coupling constants. VT NMR, ESR, and theoretical study revealed the higher stability of the singlet diradical compared to the triplet diradical.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Takashi Kubo
Summary: Unlike triplet diradicals, singlet diradicals can have variable diradical character and exhibit closed-shell or open-shell behavior depending on the external environment. This paper summarizes the progress in understanding the electronic structure and reactivity of pi-conjugated singlet diradical molecules with closed-shell and open-shell dual nature.
PURE AND APPLIED CHEMISTRY
(2023)
Article
Materials Science, Multidisciplinary
Akane Sawa, Shota Shimada, Neeti Tripathi, Claire Heck, Hiroaki Tachibana, Emiko Koyama, Toshiko Mizokuro, Yasukazu Hirao, Takashi Kubo, Naoto Tamai, Daiki Kuzuhara, Hiroko Yamada, Kenji Kamada
Summary: By introducing bulky substituents to the rubrene backbone and decreasing the sensitizer concentrations, both singlet fission and back energy transfer were suppressed, leading to a high upconversion emission efficiency of eta(UC) = (4.0 +/- 0.3)% in the cast films from the mixed solution of the sensitizer and the rubrene derivatives with tert-butyl and alkoxy groups.
JOURNAL OF MATERIALS CHEMISTRY C
(2023)
Article
Chemistry, Multidisciplinary
Tomohiko Nishiuchi, Kazuyuki Uchida, Takashi Kubo
Summary: We synthesized and characterized hexabenzo[5.6.7]quinarene, a compound composed of anthraquinodimethane (AQD) core with fluorenyl and dibenzosuberenyl end-caps. The compound exists as a stable folded form due to strong intramolecular spin-spin interaction through the central AQD unit. By oxidation and reduction of the dication, a twisted triplet species is obtained, which thermally reverts to the folded form. This is a spin-switching system using a combination of chemical oxidation/reduction and thermal stimulation.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Tomohiko Nishiuchi, Hikaru Sotome, Kazuto Shimizu, Hiroshi Miyasaka, Takashi Kubo
Summary: This study reported the synthesis of 1,2,3-tri(9-anthryl)benzene derivatives with unique electronic properties via Negishi coupling. In the crystalline state, interactions between anthracene units facilitated the formation of a two-dimensional packing structure. Understanding the excited-state dynamic behavior revealed insights into exciton localization/delocalization processes.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
