Article
Chemistry, Multidisciplinary
Taeyang An, Hanseul Ryu, Tae-Lim Choi
Summary: This study presents a versatile approach to improve the alternation and degradability of 2,3-dihydrofuran (DHF) copolymers by carefully controlling the reactivity of both the Ru initiators and the monomers. The DHF copolymers showed outstanding A, B-alternation and could be broken down to a single repeat unit level under acidic conditions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Polymer Science
Wangmeng Hou, Xiuzhe Yin, Yao Chen, Jianzhong Du, Yongming Chen, Yi Shi
Summary: A novel aqueous ring-opening metathesis polymerization method named ME-ROMP is proposed. It involves injecting a small amount of a CH2Cl2 solution of the Grubbs' third-generation catalyst into the aqueous solution of water-soluble monomers, allowing high efficiency and controlled polymerization without deoxygenation. This method enables the synthesis of well-defined water-soluble polynorbornenes with various compositions and architectures.
Article
Chemistry, Organic
Sambasivarao Kotha, Gulazarahind Mehta
Summary: In this study, we report a novel method for the synthesis of a cage-like planar carbon framework. The key steps involve Diels-Alder cycloaddition and [2+2] photocycloaddition, and strain-driven regioselective tandem ring-opening cross-metathesis is successfully applied to introduce both bicyclo[2.2.1]heptene and bicyclo[2.2.2]octene units into the linearly fused cage system.
Article
Polymer Science
Ankita Mandal, Subhajit Pal, Andreas F. M. Kilbinger
Summary: A new heterocyclic monomer is synthesized via Diels-Alder reaction and exhibits reluctant polymerization in dichloromethane (DCM) but facile polymerization in tetrahydrofuran using Grubbs' third generation catalyst (G3), with excellent control over molecular weight and dispersities. The removal of tert-butoxycarbonyl group from the polymeric backbone yields a water-soluble ring opening metathesis polymerization (ROMP) polymer. In DCM, this monomer can also copolymerize with 2,3-dihydrofuran under catalytic living ROMP conditions to produce backbone degradable polymers. All synthesized polymers are characterized by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. This new method for preparing water-soluble ROMP homopolymers and cost-effective degradable copolymers and block-copolymers may have potential applications in biomedicine.
MACROMOLECULAR RAPID COMMUNICATIONS
(2023)
Article
Chemistry, Multidisciplinary
Kaoru Tashiro, Midori Akiyama, Kimiaki Kashiwagi, Takashi Okazoe
Summary: Fluoroalkenes are notoriously difficult substrates for olefin metathesis due to the formation of stable Fischer-type fluorocarbene intermediates. However, this study discovers that fluorine substitution on sp2 carbon can also suppress homopolymerization of norbornene derivatives. By utilizing this suppression effect, alternating ring-opening metathesis polymerization (ROMP) is achieved between dihydrofuran (DHF) and fluorinated norbornenes, resulting in a copolymer with a perfectly alternating structure. Moreover, the degradability of these copolymers can be predictably modulated by the number of fluorine atoms present, allowing for control over environmental degradation while maintaining desirable physical properties.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Polymer Science
Sarah E. Blosch, Mohammed Alaboalirat, Cabell B. Eades, Samantha J. Scannelli, John B. Matson
Summary: This study investigates the influence of solvent choice and purity on the propagation rate and termination reactions in ring-opening metathesis polymerization (ROMP) reactions. It was found that the choice of solvent and its purity level can significantly affect the propagation rate and termination reactions in ROMP reactions.
Article
Polymer Science
Huiqun Wang, Sebla Onbulak, Steven Weigand, Frank S. Bates, Marc A. Hillmyer
Summary: The researchers synthesized a series of polyethylene-graft-aPP graft copolymers and found that increasing aPP content led to decreased melting temperatures and glass transition temperatures of PE, as well as decreased crystallinity. Additionally, the linear viscoelastic behavior of the PE-g-aPP graft copolymers exhibited greatly enhanced dynamic modulus and complex viscosity, with the effect increasing as side chain number and/or length increased.
Article
Polymer Science
Francis O. Boadi, Nicole S. Sampson
Summary: Bicyclo[4.2.0]oct-6-ene-7-carboxamide can form an alternating copolymer with cyclohexene in the presence of N-heterocyclic carbene-ruthenium catalyst. By creating a gradient copolymer with two different monomers, specific surface hydrophobicity, topology, and thermal properties can be controlled.
Article
Polymer Science
Mohammad Yasir, Andreas F. M. Kilbinger
Summary: Norbornene and cyclohexene show different polymerization behaviors using Grubbs' catalysts due to their varying ring strain energy levels; a sequence-selective cascade polymerization of a monomer containing both rings resulted in polymers with moderate molecular weight dispersities and good control over molecular weight.
Article
Chemistry, Multidisciplinary
Changxia Shi, Ryan W. Clarke, Michael L. McGraw, Eugene Y-X Chen
Summary: By creating an LCT/LCT hybrid monomer, orthogonal polymerization of gamma-BL and cyclohexene can be achieved, and reversible depolymerization can be conducted under mild conditions. This approach enables the production of thermally robust but recyclable polymeric materials, with the potential for flexible tuning of material properties.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Multidisciplinary
Francis O. Boadi, Nicole S. Sampson
Summary: This study investigates the rates of ruthenium-catalyzed alternating ring opening metathesis (AROM) of cyclohexene using two different Ru-cyclohexylidenecarbenes derived from bicyclo[4.2.0]oct-6-ene-7-carboxamides with different side chains. The substitution of the amide directly affects the rate of ring opening of the bicyclo[4.2.0]oct-6-ene-7-carboxamide and the reaction rate of the resulting carbene with cyclohexene. Different factors, such as the stability of ligated complexes and the relative rates of ring opening reactions, are considered to determine the kinetics and gradient copolymer structures.
ACS ORGANIC & INORGANIC AU
(2023)
Article
Polymer Science
Hongyuan Bai, Li Han, Xuefei Wang, Hong Yan, Haitao Leng, Siwei Chen, Hongwei Ma
Summary: In this study, a strategy to synthesize unique C7 and C8 skeleton polymers through living anionic polymerization was proposed. The polymerization behavior of two diene monomers with high ring strain substituents was investigated. It was found that the content of C4 and C7/C8 skeleton structures in the chain can be controlled by adjusting the mode of monomer additions.
Article
Polymer Science
Sebla Onbulak, Marc A. Hillmyer
Summary: The synthesis of sequence-controlled poly(ethylene-co-styrene) copolymers is challenging due to limitations in catalytic olefin polymerizations. An alternative method using ROMP of cyclic olefins followed by hydrogenation can generate ethylene copolymers with regioregularity. Investigating the ROMP of low-strain cyclododecenes provided useful information for mechanistic aspects of polymerization.
Article
Chemistry, Physical
Rubina Troiano, Chiara Costabile, Fabia Grisi
Summary: Grubbs- and Hoveyda-Grubbs-type olefin metathesis catalysts with N-cyclopentyl/N'-mesityl backbone-substituted N-heterocyclic carbene (NHC) ligands were synthesized and their ability to promote the alternating ring-opening metathesis copolymerization (ROMP) of norbornene (NBE) with cyclooctene (COE) or cyclopentene (CPE) was evaluated. High degrees of chemoselectivity were achieved in both copolymerizations, with up to 98% and 97% of alternating diads for NBE-COE and NBE-CPE copolymers, respectively, at low comonomer ratios. Density functional theory (DFT) studies showed that both the sterical and electronic effects of NHC ligands influence catalyst selectivity.
Article
Chemistry, Multidisciplinary
Gue Seon Lee, Hyo Won Lee, Hyun Sub Lee, Taeyang Do, Jean-Louis Do, Jeewoo Lim, Gregory Peterson, Tomislav Friscic, Jeung Gon Kim
Summary: Ruthenium-alkylidene initiated ring-opening metathesis polymerization has been successfully achieved under solid-state conditions using a mechanochemical ball milling method. This method offers a green approach and expands the range of mechano-exclusive products. The Grubbs 3(rd)-generation complex based on carbene and pyridine catalysts outperforms other catalysts and retains similar mechanistic features as solution-phase reactions. High-speed ball milling provides sufficient mixing and energy to minimize or eliminate the use of solvents. The addition of a small amount of liquid additive enables the synthesis of high-molecular-weight polymers by minimizing chain-degradation.
Article
Biochemistry & Molecular Biology
John E. Gadbery, James W. Round, Tianao Yuan, Matthew F. Wipperman, Keith T. Story, Adam M. Crowe, Israel Casabon, Jie Liu, Xinxin Yang, Lindsay D. Eltis, Nicole S. Sampson
Article
Polymer Science
Francis O. Boadi, Jingling Zhang, Xiaoxi Yu, Surita R. Bhatia, Nicole S. Sampson
Article
Chemistry, Medicinal
Amber C. Bonds, Tianao Yuan, Joshua M. Werman, Jungwon Jang, Rui Lu, Natasha M. Nesbitt, Miguel Garcia-Diaz, Nicole S. Sampson
ACS INFECTIOUS DISEASES
(2020)
Article
Biochemistry & Molecular Biology
Gyusaang Youn, Jakob Cervin, Xiaoxi Yu, Surita R. Bhatia, Ulf Yrlid, Nicole S. Sampson
Article
Chemistry, Medicinal
Tianao Yuan, Joshua M. Werman, Xingyu Yin, Meng Yang, Miguel Garcia-Diaz, Nicole S. Sampson
Summary: The study identified and characterized two genes involved in cholesterol catabolism in Mtb, shedding light on the unique metabolic pathway utilized by the bacterium. The protein products of these genes play crucial roles in the beta-oxidation of cholesterol, with distinct stereospecific hydration and dehydrogenation steps that differ from other species. The structural analysis of the enzymes reveals potential targets for therapeutic development against Mtb infection.
ACS INFECTIOUS DISEASES
(2021)
Article
Immunology
Thabatta L. S. A. Rosa, Maria Angela M. Marques, Zachary DeBoard, Kelly Hutchins, Carlos Adriano A. Silva, Christine R. Montague, Tianao Yuan, Julio J. Amaral, Georgia C. Atella, Patricia S. Rosa, Katherine A. Mattos, Brian C. VanderVen, Ramanuj Lahiri, Nicole S. Sampson, Patrick J. Brennan, John T. Belisle, Maria Cristina Pessolani, Marcia Berredo-Pinho
Summary: Upon infection, Mycobacterium leprae induces accumulation of cholesterol in Schwann cells, which is potentially delivered to the intracellular bacterium. Cholesterol oxidation is an essential catabolic pathway for M. leprae pathogenicity, with 3 beta-HSD as a potential drug target for leprosy treatment.
FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY
(2021)
Article
Infectious Diseases
Xinxin Yang, Matthew F. Wipperman, Sharon Nachman, Nicole S. Sampson
Summary: Current TB diagnostic methods developed for adults are not suitable for children, especially those who are co-infected with HIV. This study established an ELISA assay to detect modified lipoprotein in plasma, which showed lower levels of TLP in active TB patients. This suggests that TLP has potential as a biomarker for TB detection in children.
BMC INFECTIOUS DISEASES
(2022)
Correction
Immunology
Thabatta L. S. A. Rosa, Maria Angela M. Marques, Zachary DeBoard, Kelly Hutchins, Carlos Adriano A. Silva, Christine R. Montague, Tianao Yuan, Julio J. Amaral, Georgia C. Atella, Patricia S. Rosa, Katherine A. Mattos, Brian C. VanderVen, Ramanuj Lahiri, Nicole S. Sampson, Patrick J. Brennan, John T. Belisle, Maria Cristina V. Pessolani, Marcia Berredo-Pinho
FRONTIERS IN CELLULAR AND INFECTION MICROBIOLOGY
(2021)
Article
Polymer Science
Xiaoxi Yu, Guofang Li, Bingqian Zheng, Gyusaang Youn, Ting Jiang, Suan P. Quah, Scott T. Laughlin, Nicole S. Sampson, Surita R. Bhatia
Summary: This study investigates the interfacial rheology of sequence-controlled copolymers and finds that an increase in microblock size enhances the interfacial storage modulus, thereby tuning surface and interfacial properties. The research indicates that microblock size can be utilized to control the interfacial rheology of amphiphilic copolymers, providing a new strategy for controlling the dynamics of fluid interfaces through precision sequence-controlled polymers.
MACROMOLECULAR CHEMISTRY AND PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Francis O. Boadi, Nicole S. Sampson
Summary: This study investigates the rates of ruthenium-catalyzed alternating ring opening metathesis (AROM) of cyclohexene using two different Ru-cyclohexylidenecarbenes derived from bicyclo[4.2.0]oct-6-ene-7-carboxamides with different side chains. The substitution of the amide directly affects the rate of ring opening of the bicyclo[4.2.0]oct-6-ene-7-carboxamide and the reaction rate of the resulting carbene with cyclohexene. Different factors, such as the stability of ligated complexes and the relative rates of ring opening reactions, are considered to determine the kinetics and gradient copolymer structures.
ACS ORGANIC & INORGANIC AU
(2023)
Article
Chemistry, Medicinal
Joshua M. Werman, Yu-Ching Chen, Tianao Yuan, Xinxin Yang, Nicole S. Sampson
Summary: By studying the effects of 6-azasteroid analogs on Mycobacterium tuberculosis and Mycobacterium marinum, we can enhance the antimycobacterial activity and gain a better understanding of the mechanism behind the potentiation of the antituberculosis drug bedaquiline.
ACS INFECTIOUS DISEASES
(2023)
Article
Polymer Science
Francis O. Boadi, Nicole S. Sampson
Summary: Bicyclo[4.2.0]oct-6-ene-7-carboxamide can form an alternating copolymer with cyclohexene in the presence of N-heterocyclic carbene-ruthenium catalyst. By creating a gradient copolymer with two different monomers, specific surface hydrophobicity, topology, and thermal properties can be controlled.
Article
Chemistry, Multidisciplinary
Gyusaang Youn, Nicole S. Sampson
Summary: This study reveals the unexpected reactivity of bicyclo[4.2.0] oct-6-ene substrates containing an alpha,ss-unsaturated amide moiety in ruthenium-catalyzed alternating ring-opening metathesis polymerization reactions. H-1 NMR and IR spectral analyses, as well as principal component analysis, are used to understand the reaction mechanism and identify key contributors to the fast ring-opening metathesis of the substrates.
ACS ORGANIC & INORGANIC AU
(2021)
Review
Biochemistry & Molecular Biology
Tianao Yuan, Joshua M. Werman, Nicole S. Sampson
Summary: Whole cell-based phenotypic screens have become the primary mode of hit generation in tuberculosis drug discovery over the past two decades, with different drug screening models developed to mimic the complexity of TB disease in the lab. Understanding the mechanism of action of TB drugs is essential for successful drug delivery due to the complex interactions between Mycobacterium tuberculosis and the drugs used for treatment.
RSC CHEMICAL BIOLOGY
(2021)
Article
Polymer Science
Jingling Zhang, Xiaoxi Yu, Bingqian Zheng, Jiachun Shen, Surita R. Bhatia, Nicole S. Sampson