Article
Chemistry, Multidisciplinary
Yueyao Chen, Jesse Ling, Angus B. Keto, Yun He, Kam-Hung Low, Elizabeth H. Krenske, Pauline Chiu
Summary: Epoxy and aziridinyl enolsilanes can react as oxyallylic cation equivalents in highly selective and stereoselective intramolecular (3+2) cycloadditions. Computational studies suggest that the stepwise reaction involves the conformational flexibility of the intermediate, which determines the formation of (3+2) cycloadducts. This method can be used for the synthesis of densely functionalized trans-hydrindane scaffolds.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Huan Hu, Xin Cheng, Zhimin Ma, Rint P. Sijbesma, Zhiyong Ma
Summary: This study reports the development of a mechanochromic mechanophore based on excited-state intramolecular proton transfer (ESIPT) for real-time strain sensing in polyurethane films. The mechanophore exhibited high sensitivity and excellent reversibility to stress, and the mechanochromism was attributed to chain-transduced force. Density function theory (DFT) calculation was performed to analyze the force-tuned ESIPT process. This research lays the foundation for practical applications in real-time stress/strain sensing.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Ankita Das, Ayan Datta
Summary: Mechanical force can release small molecules from macromolecular carriers in a predictable and precise manner. Using mechanochemical simulations, this study demonstrates that norborn-2-en-7-one (NEO) and its derivatives can selectively release CO, N-2, and SO2 to generate two distinct products A and B. The regioselectivity in the pulling points enables the exclusive formation of either A or B. Through changing the rigidity of the NEO scaffold and tuning the pulling groups, control over the selective formation of B is achieved. The diradical intermediate formed during the conversion of I to A is predicted to be persistent for approximately 150 fs. Structural design plays a crucial role in balancing the mechanochmeical rigidity and lability.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Multidisciplinary
Hajime Sugita, Yi Lu, Daisuke Aoki, Hideyuki Otsuka, Koichiro Mikami
Summary: In this study, the synthesis and characterization of two series of arylfluorene-based mechanophores were reported. Density functional theory (DFT) calculations revealed the importance of thermodynamic stability and oxygen tolerance for the functions and applicability of these materials. Furthermore, the mechanochromism of a polymer containing one of the mechanophores was demonstrated through ball-milling.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Hajime Sugita, Yi Lu, Daisuke Aoki, Hideyuki Otsuka, Koichiro Mikami
Summary: Radical-type mechanophores (RMs) can undergo homolytic cleavage of their central C-C bonds upon exposure to mechanical forces, which affords radical species. Understanding the characteristics of these radical species allows bespoke mechanoresponsive materials to be designed and developed. In this paper, the synthesis and characterization of arylfluorene-based RM derivatives, and the importance of thermodynamic stability and oxygen tolerance for their functions and applicability, are reported. Furthermore, the mechanochromism of a BTAF-centered polymer synthesized by ATRP was demonstrated.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Polymer Science
Xiaoying Wang, Yifeng Cao, Yanling Peng, Lewen Wang, Wangmeng Hou, Yecheng Zhou, Yi Shi, Huahua Huang, Yongming Chen, Yuanchao Li
Summary: This novel mechanophore undergoes a chemical reaction upon mechanical activation, resulting in the generation of two new substances with different fluorescent colors. It also exhibits sensitivity to solvents, enabling dual-color mechanochromism.
Article
Polymer Science
Kuniaki Ishizuki, Daisuke Aoki, Hideyuki Otsuka
Summary: Mechanochromic polymers can be used as sensors to detect stress and damage in polymeric materials by visualizing mechanical stimuli through color changes. By mixing white powders of two mechanochromic polystyrene samples with different mechanochromophores, the duration of mechanical stimulation can be detected through multicolor mechanochromism, allowing for distinguishing between short and long exposure to grinding.
MACROMOLECULAR RAPID COMMUNICATIONS
(2021)
Article
Chemistry, Multidisciplinary
Ross W. Barber, Maxwell J. Robb
Summary: A novel mechanophore platform for mechanically gated photoswitching has been developed, allowing the mechanical history of a material to be recorded using light. Experimental results show that this platform can produce chromogenic responses under UV irradiation, and has been successfully applied to solid polymeric materials, demonstrating its wide range of potential applications.
Article
Chemistry, Multidisciplinary
Yan Sun, Molly E. Mcfadden, Skylar K. Osler, Ross W. Barber, Maxwell J. Robb
Summary: In contrast to angular naphthopyrans, linear naphthopyrans are typically not photochromic. However, the incorporation of a polarizing dialkylamine substituent enables photochromic and mechanochromic behavior in polymers containing a novel linear naphthopyran motif.
Article
Chemistry, Multidisciplinary
Sangmin Jung, Hyo Jae Yoon
Summary: This study reports the incorporation of cis-N-phthalimidoaziridine into a macromolecular backbone, leading to the migration of the N-phthalimido group to form an imine under mechanochemical conditions. The imine is then hydrolyzed by water to produce amine and aldehyde. Structural transformations are confirmed through H-1 NMR and FT-IR spectroscopic analyses, and computational simulations are used to propose the reaction mechanism and define the substrate scope.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Hang Shen, Michael B. Larsen, Allison G. Roessler, Paul M. Zimmerman, Andrew J. Boydston
Summary: A new flex-activated mechanophore has been discovered, which releases an N-heterocyclic carbene (NHC) under mechanical load. This design demonstrates a promising first step towards flex-activated designs with downstream reactivities, allowing for iterative activation increases in the material through non-destructive compression cycles. The potential modularity of the mechanophore design is highlighted by the demonstration of two different NHC structures.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Mingkai Zhang, Peilin Xu, Alex J. Vendola, Christophe Allais, Anne-Marie Dechert Schmitt, Robert A. Singer, James P. Morken
Summary: This paper describes an easily synthesized chiral diazaborolidine that is inexpensive, stable, and exhibits excellent stereoselection across multiple reaction classes. These versatile compounds have utility in four different classes of cycloaddition reactions, offering good yield and stereoselectivity. X-ray structure analysis provides insight into the origin of stereocontrol.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Polymer Science
Anatoly T. Ponomarenko, Alexey R. Tameev, Vitaliy G. Shevchenko
Summary: This review summarizes recent developments in the field of mechanochemistry of polymers, focusing on the consequences of mechanical forces and actions on polymers and polymer synthesis. Classical works on chemical reactions and polymerization processes under strong shear deformations are reviewed, followed by an analysis of two emerging directions of research in mechanochemistry - the role of mechanophores and new physical phenomena accompanying external impulse mechanical actions on polymers. These studies provide deeper insights into the mechanism of chemical reactions under shear deformations and pave the way for further research in modern technologies.
Article
Chemistry, Multidisciplinary
Raphael Hertel, Wafa Maftuhin, Michael Walter, Michael Sommer
Summary: In this study, we used a series of thiophene-flanked quinoxalines as molecular torsional springs for force sensing in bulk polymers at room temperature. Through detailed spectroscopy and calculations, we identified the thiophene ring flip as the major part of the overall mechanochromic response. The thiophene ring flip requires much smaller forces than planarization of the DAD spring, allowing for sensing of tiny forces and expanding the sensitivity and force range of conformational mechanochromophores.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Anton O. Razgoniaev, Logan M. Glasstetter, Tatiana B. Kouznetsova, Kacey C. Hall, Matias Horst, Stephen L. Craig, Katherine J. Franz
Summary: The experimental characterization of the mechanochemical scission of metal-NHC bonds in N-heterocyclic carbene mechanophores has been reported. The study reveals a force-coupled rate constant for ligand dissociation and supports a dissociative mechanism of ligand displacement, with the rate-limiting scission of Pd-NHC bond followed by rapid dissociation of the pyridine moiety from Pd.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Nanoscience & Nanotechnology
Sohyun Park, Hyo Jae Yoon
Summary: This study systematically investigates the thermal properties of self-assembled monolayer (SAM)-based molecular junctions and reveals that SAM plays a key role in creating a temperature differential across the junction. The new optimal condition, under a vacuum and with thermal grease, allows for more reliable thermoelectric performance data.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
Hungu Kang, Hyerim Jeong, Sicheon Seong, Seulki Han, Young Ji Son, Hiroyuki Tahara, Tomohiro Hayashi, Hyo Jae Yoon, Jaegeun Noh
Summary: The study investigates the formation and surface structures of cyclohexanethiolate (CYH-S) and cyclohexaneselenolate (CYH-Se) SAMs on gold electrodes, revealing significant differences in their formation and structures. Furthermore, it was found that both types of SAMs could be used for modifying the work function of the gold substrate through Kelvin probe force microscopy measurements.
APPLIED SURFACE SCIENCE
(2022)
Article
Polymer Science
Hong Diem Chau, Meenal Kataria, Na Yeon Kwon, Su Hong Park, Youngseo Kim, Hungu Kang, Amit Kumar Harit, Han Young Woo, Hyo Jae Yoon, Sungnam Park, Min Ju Cho, Dong Hoon Choi
Summary: Recently, there have been significant improvements in the power conversion efficiencies of all-polymer solar cells through the development of high-performance polymer donors and acceptors. This study synthesized a new low-bandgap polymer acceptor and introduced a ternary system to enhance light-harvesting properties and morphology, resulting in a high PCE of 8.03%.
MACROMOLECULAR RESEARCH
(2022)
Article
Chemistry, Multidisciplinary
Sohyun Park, Seohyun Kang, Hyo Jae Yoon
Summary: This study demonstrates the stability and thermoelectric effect of molecular junctions based on N-Heterocyclic carbene (NHC) at high temperatures, providing a roadmap for constructing efficient organic thermoelectric devices.
Article
Chemistry, Organic
Hee Jin Jeong, Ji Ho Kim, Jae Kyun Lee, Hyo Jae Yoon, Junwon Choi, Seo-Jung Han
Summary: An efficient and transition-metal-free three-component reaction was developed for the synthesis of benzoxaphosphole 1-oxides. This reaction is useful for preparing organophosphorus compounds encountered in natural products and materials.
Article
Nanoscience & Nanotechnology
Na Yeon Kwon, Su Hong Park, Yoonjoo Lee, Gyu Don Kong, Hong Diem Chau, Hyo Jae Yoon, Han Young Woo, Mai Ha Hoang, Min Ju Cho, Dong Hoon Choi
Summary: This study presents a new strategy for improving the adhesion and dispersion of AgNW electrodes by introducing a polymer on the plastic substrate and using specific coatings to improve surface roughness and achieve effective electrode patterns. Optimized AgNW electrodes demonstrated low sheet resistance and high transmittance. A fabricated polymer solar cell showed high power conversion efficiency and excellent mechanical stability.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Hungu Kang, Soo Jin Cho, Gyu Don Kong, Hyo Jae Yoon
Summary: This paper describes the effect of Li-ion intercalation into a pyrenyl-terminated self-assembled monolayer (SAM) on tunneling performance in a molecular junction. The rectification ratio increased with the concentration of the Li-ion precursor, while treatment with high concentrations of Li-ion resulted in the disappearance of rectification due to the formation of a solid electrolyte interphase (SEI) on the surface of the SAM.
Article
Biochemistry & Molecular Biology
Hee Jin Jeong, Hye Lim Lee, Sung Joon Kim, Jeong Hyun Jeong, Su Hyun Ji, Han Byeol Kim, Miso Kang, Hwan Won Chung, Chan Sun Park, Hyunah Choo, Hyo Jae Yoon, Nam-Jung Kim, Duck-Hyung Lee, Sang Hee Lee, Seo-Jung Han
Summary: In this study, novel ENPP1 inhibitors were designed and synthesized to stimulate the STING pathway and inhibit tumor growth. The compound 18p showed high potency against ENPP1 and activated the STING pathway, leading to the induction of cytokines and inhibition of tumor growth in a mouse model.
JOURNAL OF ENZYME INHIBITION AND MEDICINAL CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Sohyun Park, Jeong Woo Jo, Jiung Jang, Tatsuhiko Ohto, Hirokazu Tada, Hyo Jae Yoon
Summary: This paper investigates the Seebeck effect in molecular epitaxy films and finds that the Seebeck coefficient increases linearly with the molecular length. Experimental and theoretical studies indicate that this change is attributed to a transition from tunneling to hopping.
Article
Nanoscience & Nanotechnology
Gyu Don Kong, Hyunsun Song, Hungu Kang, Junji Jin, Sahar Ayachi, Hyo Jae Yoon
Summary: This paper describes charge tunneling across mixed self-assembled monolayers (SAMs) and investigates the effect of the bottom electrode on molecular dilution and tunneling function in large-area molecular junctions. The study found that the effect of molecular dilution on tunneling can be reversed by varying the bottom electrode.
ADVANCED ELECTRONIC MATERIALS
(2022)
Article
Chemistry, Physical
Hungu Kang, Soo Jin Cho, Gyu Don Kong, Sohyun Park, Hyo Jae Yoon
Summary: The rectification performance of pyrene-terminated alkanethiolate in large-area tunneling junction was investigated, and it was found that the identity of the bottom electrode (Ag, Au, Pt, Pd) significantly affected the rectification ratio. The analysis revealed that the bottom electrode's effect on the supramolecular structure dominated the trend of rectification performance.
SURFACES AND INTERFACES
(2022)
Article
Chemistry, Physical
Sicheon Seong, Hungu Kang, Seulki Han, Young Ji Son, Jiung Jang, Hyo Jae Yoon, Shoichi Maeda, Subin Song, Debabrata Palai, Tomohiro Hayashi, Jaegeun Noh
Summary: The formation and surface structure of pentafluorobenzeneselenolate (PFB-Se) self-assembled monolayers (SAMs) on Au(111) were examined by scanning tunneling microscopy (STM). Results showed that the structural order of the SAMs was improved by vapor deposition compared to solution deposition. Kelvin probe force microscopy measurements exhibited a significant difference in the work function between pentafluorobenzenethiolate and PFB-Se SAMs due to their different domain and packing structures.
SURFACES AND INTERFACES
(2022)
Article
Chemistry, Multidisciplinary
Sohyun Park, Eunchan Kim, Youngjin Choi, Jiung Jang, Kyungwon Kwak, Minhaeng Cho, Hyo Jae Yoon
Summary: This study investigated the thermoresponse of odd-even effect in self-assembled monolayers (SAMs) of n-alkanethiolates on template-stripped gold using contact angle goniometry and vibrational sum frequency generation spectroscopy. The results showed that the odd-even effect disappeared upon heating in liquid-like SAMs, indicating increased structural disorder. However, in wax- and solid-like SAMs, opposite thermoresponse was observed for odd and even molecules, mitigating the odd-even effect.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Physical
Yuan Li, Samuel E. Root, Lee Belding, Junwoo Park, Hyo Jae Yoon, Cancan Huang, Mostafa Baghbanzadeh, George M. Whitesides
Summary: This paper describes measurements of charge transport through molecular junctions in different external environments. The results show that the current density decreases when the junctions are immersed in organic liquids, suggesting the formation of liquid films at the interface. The study highlights the use of EGaIn junction and tunneling current measurements as a new surface analysis method.
JOURNAL OF PHYSICAL CHEMISTRY B
(2023)
Article
Chemistry, Multidisciplinary
Sohyun Park, Jiung Jang, Yuya Tanaka, Hyo Jae Yoon
Summary: This paper describes the thermoelectric properties of molecular junctions incorporating multinuclear ruthenium alkynyl complexes. High Seebeck coefficients and thermal stability were observed, providing important insights into the development of molecular-scale devices for efficient thermoregulation and heat-to-electricity conversion.
