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Oka T, Yamamura Y, Kutsumizu S, Saito K. Aggregation structure of chiral cubic liquid crystals revealed by X-ray diffraction utilizing a new algorithm. SOFT MATTER 2023; 19:1194-1201. [PMID: 36655785 DOI: 10.1039/d2sm01687g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Chiral aggregation structure spontaneously formed by achiral rodlike molecules, a long-time unsolved problem in liquid crystal science, has been clarified by applying a new crystallographic algorithm recently developed while utilizing aggregation characteristics of this type. Bicontinuously interwoven networks characterize it similarly to the neighboring Gyroid phase in a phase diagram against the alkyl chain length and temperature. However, the network connectivity is significantly different from the bicontinuous networks that have been either known for related compounds or assumed for this phase. The network is compatible with the homochiral arrangement of rodlike molecules with successive twists by a proper angle between adjacent junctions.
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Affiliation(s)
- Toshihiko Oka
- Department of Physics, Faculty of Science, and Nanomaterials Research Division, Research Institute of Electronics, Shizuoka University, Shizuoka 422-8529, Japan
| | - Yasuhisa Yamamura
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
| | - Shoichi Kutsumizu
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, Yanagido, Gifu 501-1193, Japan
| | - Kazuya Saito
- Department of Chemistry, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan.
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2
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Cao Y, Alaasar M, Zhang L, Zhu C, Tschierske C, Liu F. Supramolecular meso-Trick: Ambidextrous Mirror Symmetry Breaking in a Liquid Crystalline Network with Tetragonal Symmetry. J Am Chem Soc 2022; 144:6936-6945. [PMID: 35394276 DOI: 10.1021/jacs.2c01511] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Bicontinuous and multicontinuous network phases are among nature's most complex structures in soft matter systems. Here, a chiral bicontinuous tetragonal phase is reported as a new stable liquid crystalline intermediate phase at the transition between two cubic phases, the achiral double gyroid and the chiral triple network cubic phase with an I23 space group, both formed by dynamic networks of helices. The mirror symmetry of the double gyroid, representing a meso-structure of two enantiomorphic networks, is broken at the transition to this tetragonal phase by retaining uniform helicity only along one network while losing it along the other one. This leads to a conglomerate of enantiomorphic tetragonal space groups, P41212 and P43212. Phase structures and chirality were analyzed by small-angle X-ray scattering (SAXS), grazing-incidence small-angle X-ray scattering (GISAXS), resonant soft X-ray scattering (RSoXS) at the carbon K-edge, and model-dependent SAXS/RSoXS simulation. Our findings not only lead to a new bicontinuous network-type three-dimensional mesophase but also reveal a mechanism of mirror symmetry breaking in soft matter by partial meso-structure racemization at the transition from enantiophilic to enantiophobic interhelical self-assembly.
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Affiliation(s)
- Yu Cao
- Shaanxi International Research Center for Soft Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, P. R. China.,MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Mohamed Alaasar
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt Mothes Str. 2, Halle (Saale) D-06120, Germany.,Department of Chemistry, Cairo University, Giza 12613, Egypt
| | - Lei Zhang
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, China
| | - Chenhui Zhu
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
| | - Carsten Tschierske
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt Mothes Str. 2, Halle (Saale) D-06120, Germany
| | - Feng Liu
- Shaanxi International Research Center for Soft Matter, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, P. R. China
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3
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Alaasar M, Cai X, Kraus F, Giese M, Liu F, Tschierske C. Controlling ambidextrous mirror symmetry breaking in photosensitive supramolecular polycatenars by alkyl-chain engineering. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118597] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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4
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Alaasar M, Darweesh AF, Cai X, Liu F, Tschierske C. Mirror Symmetry Breaking and Network Formation in Achiral Polycatenars with Thioether Tail. Chemistry 2021; 27:14921-14930. [PMID: 34542201 PMCID: PMC8596804 DOI: 10.1002/chem.202102226] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Indexed: 11/20/2022]
Abstract
Mirror symmetry breaking in systems composed of achiral molecules is of importance for the design of functional materials for technological applications as well as for the understanding of the mechanisms of spontaneous emergence of chirality. Herein, we report the design and molecular self-assembly of two series of rod-like achiral polycatenar molecules derived from a π-conjugated 5,5'-diphenyl-2,2'-bithiophene core with a fork-like triple alkoxylated end and a variable single alkylthio chain at the other end. In both series of liquid crystalline materials, differing in the chain length at the trialkoxylated end, helical self-assembly of the π-conjugated rods in networks occurs, leading to wide temperature ranges (>200 K) of bicontinuous cubic network phases, in some cases being stable even around ambient temperatures. The achiral bicontinuous cubic Ia 3 ‾ d phase (gyroid) is replaced upon alkylthio chain elongation by a spontaneous mirror symmetry broken bicontinuous cubic phase (I23) and a chiral isotropic liquid phase (Iso1 [ *] ). Further chain elongation results in removing the I23 phase and the re-appearance of the Ia 3 ‾ d phase with different pitch lengths. In the second series an additional tetragonal phase separates the two cubic phase types.
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Affiliation(s)
- Mohamed Alaasar
- Institute of ChemistryMartin Luther University Halle-WittenbergKurt Mothes Str. 206120Halle (Saale)Germany
- Department of Chemistry Faculty of ScienceCairo UniversityGizaEgypt
| | | | - Xiaoqian Cai
- State Key Laboratory for Mechanical Behavior of Materials Shaanxi International Research Center for Soft MatterXi'an Jiaotong UniversityXi'an710049P. R. China
| | - Feng Liu
- State Key Laboratory for Mechanical Behavior of Materials Shaanxi International Research Center for Soft MatterXi'an Jiaotong UniversityXi'an710049P. R. China
| | - Carsten Tschierske
- Institute of ChemistryMartin Luther University Halle-WittenbergKurt Mothes Str. 206120Halle (Saale)Germany
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5
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Kwon O, Cai X, Saeed A, Liu F, Poppe S, Tschierske C. 2,6-Dibromogallates as a new building block for controlling π-stacking, network formation and mirror symmetry breaking. Chem Commun (Camb) 2021; 57:6491-6494. [PMID: 34100483 DOI: 10.1039/d1cc01922h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Achiral multi-chain (polycatenar) compounds based on the 2,7-diphenyl substituted [1]benzothieno[3,2-b]benzothiophene (BTBT) unit and a 2,6-dibromo-3,4,5-trialkoxybenzoate end group lead to materials forming bicontinuous cubic liquid crystalline phases with helical network structures over wide temperature ranges.
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Affiliation(s)
- Ohjin Kwon
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle (Saale), Germany.
| | - Xiaoqian Cai
- State Key Laboratory for Mechanical Behaviour of Materials, Shaanxi International Research Center for Soft Matter, Xi'an Jiaotong University, Xi'an 710049, P. R. China.
| | - Azhar Saeed
- State Key Laboratory for Mechanical Behaviour of Materials, Shaanxi International Research Center for Soft Matter, Xi'an Jiaotong University, Xi'an 710049, P. R. China.
| | - Feng Liu
- State Key Laboratory for Mechanical Behaviour of Materials, Shaanxi International Research Center for Soft Matter, Xi'an Jiaotong University, Xi'an 710049, P. R. China.
| | - Silvio Poppe
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle (Saale), Germany.
| | - Carsten Tschierske
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt-Mothes Str. 2, 06120 Halle (Saale), Germany.
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6
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Nicosia A, Vento F, Marletta G, Messina GML, Satriano C, Villari V, Micali N, De Martino MT, Schotman MJG, Mineo PG. Porphyrin-Based Supramolecular Flags in the Thermal Gradients' Wind: What Breaks the Symmetry, How and Why. NANOMATERIALS 2021; 11:nano11071673. [PMID: 34202150 PMCID: PMC8305271 DOI: 10.3390/nano11071673] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 06/21/2021] [Accepted: 06/23/2021] [Indexed: 01/04/2023]
Abstract
The Spontaneous Symmetry Breaking (SSB) phenomenon is a natural event in which a system changes its symmetric state, apparently reasonless, in an asymmetrical one. Nevertheless, this occurrence could be hiding unknown inductive forces. An intriguing investigation pathway uses supramolecular aggregates of suitable achiral porphyrins, useful to mimic the natural light-harvesting systems (as chlorophyll). Using as SSB probe supramolecular aggregates of 5,10,15,20-tetrakis[p(ω-methoxypolyethyleneoxy)phenyl]porphyrin (StarP), a non-ionic achiral PEGylated porphyrin, we explore here its interaction with weak asymmetric thermal gradients fields. The cross-correlation of the experimental data (circular dichroism, confocal microscopy, atomic force microscopy, and cryo-transmission electron microscopy) revealed that the used building blocks aggregate spontaneously, organizing in flag-like structures whose thermally-induced circular dichroism depends on their features. Finally, thermal gradient-induced enantioselectivity of the supramolecular flag-like aggregates has been shown and linked to their size-dependence mesoscopic deformation, which could be visualized as waving flags in the wind.
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Affiliation(s)
- Angelo Nicosia
- Department of Chemical Sciences and INSTM UdR of Catania, University of Catania, Viale A. Doria 6, I-95125 Catania, Italy; (F.V.); (G.M.); (G.M.L.M.); (C.S.)
- Correspondence: (A.N.); (P.G.M.)
| | - Fabiana Vento
- Department of Chemical Sciences and INSTM UdR of Catania, University of Catania, Viale A. Doria 6, I-95125 Catania, Italy; (F.V.); (G.M.); (G.M.L.M.); (C.S.)
| | - Giovanni Marletta
- Department of Chemical Sciences and INSTM UdR of Catania, University of Catania, Viale A. Doria 6, I-95125 Catania, Italy; (F.V.); (G.M.); (G.M.L.M.); (C.S.)
- LAMSUN-CSGI Unit of the Interuniversity Consortium for the Development of Large Interphases Systems (CSGI), Università di Catania, Viale A. Doria, 6, I-95125 Catania, Italy
| | - Grazia M. L. Messina
- Department of Chemical Sciences and INSTM UdR of Catania, University of Catania, Viale A. Doria 6, I-95125 Catania, Italy; (F.V.); (G.M.); (G.M.L.M.); (C.S.)
- LAMSUN-CSGI Unit of the Interuniversity Consortium for the Development of Large Interphases Systems (CSGI), Università di Catania, Viale A. Doria, 6, I-95125 Catania, Italy
| | - Cristina Satriano
- Department of Chemical Sciences and INSTM UdR of Catania, University of Catania, Viale A. Doria 6, I-95125 Catania, Italy; (F.V.); (G.M.); (G.M.L.M.); (C.S.)
- Consorzio Interuniversitario di Ricerca in Chimica dei Metalli nei Sistemi Biologici (CIRCMSB), Università Degli Studi di Bari Aldo Moro, I-70121 Bari, Italy
| | - Valentina Villari
- Institute for Chemical and Physical Processes, National Research Council (IPCF-CNR), Viale F. Stagno d’Alcontres 37, I-98158 Messina, Italy; (V.V.); (N.M.)
| | - Norberto Micali
- Institute for Chemical and Physical Processes, National Research Council (IPCF-CNR), Viale F. Stagno d’Alcontres 37, I-98158 Messina, Italy; (V.V.); (N.M.)
| | - Maria Teresa De Martino
- Department of Chemistry & Chemical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands;
- Institute for Complex Molecular Systems, Laboratory of Chemical Biology, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands;
| | - Maaike J. G. Schotman
- Institute for Complex Molecular Systems, Laboratory of Chemical Biology, Eindhoven University of Technology, 5612 AZ Eindhoven, The Netherlands;
| | - Placido Giuseppe Mineo
- Department of Chemical Sciences and INSTM UdR of Catania, University of Catania, Viale A. Doria 6, I-95125 Catania, Italy; (F.V.); (G.M.); (G.M.L.M.); (C.S.)
- Institute for Chemical and Physical Processes, National Research Council (IPCF-CNR), Viale F. Stagno d’Alcontres 37, I-98158 Messina, Italy; (V.V.); (N.M.)
- Institute of Polymers, Composites and Biomaterials, National Research Council (IPCB-CNR), Via P. Gaifami 18, I-95126 Catania, Italy
- Correspondence: (A.N.); (P.G.M.)
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Alaasar M, Schmidt JC, Cai X, Liu F, Tschierske C. Controlling liquid and liquid crystalline network formation by core-fluorination of hydrogen bonded supramolecular polycatenars. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115870] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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8
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Buhse T, Cruz JM, Noble-Terán ME, Hochberg D, Ribó JM, Crusats J, Micheau JC. Spontaneous Deracemizations. Chem Rev 2021; 121:2147-2229. [DOI: 10.1021/acs.chemrev.0c00819] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Thomas Buhse
- Centro de Investigaciones Químicas−IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, 62209 Cuernavaca, Morelos Mexico
| | - José-Manuel Cruz
- Facultad de Ciencias en Física y Matemáticas, Universidad Autónoma de Chiapas, Tuxtla Gutiérrez, Chiapas 29050, Mexico
| | - María E. Noble-Terán
- Centro de Investigaciones Químicas−IICBA, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, 62209 Cuernavaca, Morelos Mexico
| | - David Hochberg
- Department of Molecular Evolution, Centro de Astrobiología (CSIC-INTA), Carretera Ajalvir, Km. 4, 28850 Torrejón de Ardoz, Madrid Spain
| | - Josep M. Ribó
- Institut de Ciències del Cosmos (IEEC-ICC) and Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Catalunya Spain
| | - Joaquim Crusats
- Institut de Ciències del Cosmos (IEEC-ICC) and Departament de Química Inorgànica i Orgànica, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Catalunya Spain
| | - Jean-Claude Micheau
- Laboratoire des IMRCP, UMR au CNRS No. 5623, Université Paul Sabatier, F-31062 Toulouse Cedex, France
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9
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Reppe T, Poppe S, Tschierske C. Controlling Mirror Symmetry Breaking and Network Formation in Liquid Crystalline Cubic, Isotropic Liquid and Crystalline Phases of Benzil-Based Polycatenars. Chemistry 2020; 26:16066-16079. [PMID: 32652801 PMCID: PMC7756378 DOI: 10.1002/chem.202002869] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Indexed: 12/25/2022]
Abstract
Spontaneous development of chirality in systems composed of achiral molecules is important for new routes to asymmetric synthesis, chiral superstructures and materials, as well as for the understanding of the mechanisms of emergence of prebiotic chirality. Herein, it is shown that the 4,4'-diphenylbenzil unit is a universal transiently chiral bent building block for the design of multi-chained (polycatenar) rod-like molecules capable of forming a wide variety of helically twisted network structures in the liquid, the liquid crystalline (LC) and the crystalline state. Single polar substituents at the apex of tricatenar molecules support the formation of the achiral (racemic) cubic double network phase with Ia 3 ‾ d symmetry and relatively small twist along the networks. The combination of an alkyl chain with fluorine substitution leads to the homogeneously chiral triple network phase with I23 space group, and in addition, provides a mirror symmetry broken liquid. Replacing F by Cl or Br further increases the twist, leading to a short pitch double gyroid Ia 3 ‾ d phase, which is achiral again. The effects of the structural variations on the network structures, either leading to achiral phases or chiral conglomerates are analyzed.
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Affiliation(s)
- Tino Reppe
- Institute of ChemistryMartin Luther University Halle-WittenbergKurt-Mothes-Straße 206120HalleGermany
| | - Silvio Poppe
- Institute of ChemistryMartin Luther University Halle-WittenbergKurt-Mothes-Straße 206120HalleGermany
| | - Carsten Tschierske
- Institute of ChemistryMartin Luther University Halle-WittenbergKurt-Mothes-Straße 206120HalleGermany
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Reddy MG, Lobo NP, Roy A, Ramanathan KV, Narasimhaswamy T. Strikingly different molecular organization and molecular order of tetracatenar mesogens in columnar mesophases revealed by XRD and 13C NMR. Phys Chem Chem Phys 2020; 22:23986-23997. [PMID: 33073796 DOI: 10.1039/d0cp03933k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
For a successful design of functional mesogens, it is paramount to understand factors that contribute to molecular organisation such as molecular shape, the non-covalent interactions of the constituent moieties as well as nanosegregation of incompatible molecular parts. In this study on four tetracatenar mesogens, we show that by a slight change in the length of the terminal chain, the molecular organization changes from lamellar to columnar phase and that the orientational order experiences profound change between the lamellar, the center rectangular columnar and the hexagonal columnar mesophases. We consider here, mesogens that exhibit lamellar and columnar mesophases with five phenyl rings in the central rod-like core which are subjected to XRD and high resolution solid state 13C NMR investigations in their mesophases. The XRD studies indicate that the lower homologs exhibit a lamellar mesophase while the higher homologs show either a centre rectangular columnar phase or a 2D hexagonal columnar mesophase. 13C NMR investigations reveal interesting and strikingly different molecular orientations in each of these phases. For example, values of order parameters of one of the phenyl rings in the core region of the mesogens vary from 0.75 and 0.77 for the lamellar mesogens to 0.45 and 0.17 for the centre rectangular columnar and the hexagonal columnar mesogens respectively. While these values indicate that the mesogenic molecules are oriented along the magnetic field as expected in the lamellar phases, the very low order parameter in the hexagonal columnar phase arises due to molecules distributed azimuthally in layers and undergoing motion about the columnar axis which itself is oriented orthogonal to the magnetic field. Such cutting edge information extracted from the combined use of XRD and 13C NMR studies on tetracatenar mesogens is expected to be of significant use for the study of π-conjugated polycatenar systems where functional properties depend on the molecular orientation and order.
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Affiliation(s)
- M Guruprasad Reddy
- Polymer Science and Technology, CSIR-Central Leather Research Institute, Adyar, Chennai 600020, India.
| | - Nitin P Lobo
- Centre for Analysis, Testing, Evaluation & Reporting Services (CATERS), CSIR-Central Leather Research Institute, Adyar, Chennai 600020, India
| | - Arun Roy
- Soft Condensed Matter, Raman Research Institute, Bangalore, 560080, India.
| | - K V Ramanathan
- NMR Research Centre, Indian Institute of Science, Bangalore, 560012, India.
| | - T Narasimhaswamy
- Polymer Science and Technology, CSIR-Central Leather Research Institute, Adyar, Chennai 600020, India.
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Wang F, Gan F, Shen C, Qiu H. Amplifiable Symmetry Breaking in Aggregates of Vibrating Helical Molecules. J Am Chem Soc 2020; 142:16167-16172. [DOI: 10.1021/jacs.0c06932] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Fang Wang
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Fuwei Gan
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chengshuo Shen
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Huibin Qiu
- School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China
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12
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Tortora C, Mai C, Cascella F, Mauksch M, Seidel‐Morgenstern A, Lorenz H, Tsogoeva SB. Speeding up Viedma Deracemization through Water-catalyzed and Reactant Self-catalyzed Racemization. Chemphyschem 2020; 21:1775-1787. [PMID: 32519414 PMCID: PMC7497082 DOI: 10.1002/cphc.202000493] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Indexed: 01/23/2023]
Abstract
Viedma deracemization is based on solution phase racemization, dissolution of racemic or scalemic conglomerates and crystal growth through autocatalytic cluster formation. With rate limiting racemization, its acceleration by appropriate catalysts may result in speeding up deracemization. A conglomerate-forming chiral compound may principally racemize directly, or via reverse of its formation reaction. For a hydrazine derivative, we investigated available racemization pathways in presence of pyrrolidine or thiourea amine as base catalysts: via Mannich or aza-Michael reaction steps and their reverse, or by enolization. Racemization by enolization was computationally found to dominate, both under water-free conditions and in presence of water, involving a multitude of different pathways. Faster racemization in presence of water resulted indeed in more rapid deracemization, when the base was pyrrolidine. Under water-free conditions, the role of water as enolization catalyst is assumed by chiral hydrazine itself - in autocatalytic racemization and in which both reactant and product are catalysts.
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Affiliation(s)
- Carola Tortora
- Organic Chemistry Chair I and Interdisciplinary Center for Molecular Materials (ICMM)Friedrich-Alexander University of Erlangen-NürnbergNikolaus-Fiebiger-Strasse 1091058ErlangenGermany
| | - Christina Mai
- Organic Chemistry Chair I and Interdisciplinary Center for Molecular Materials (ICMM)Friedrich-Alexander University of Erlangen-NürnbergNikolaus-Fiebiger-Strasse 1091058ErlangenGermany
| | - Francesca Cascella
- Max Planck Institute for Dynamics of Complex Technical SystemsSandtorstraße 139106MagdeburgGermany
- Otto von Guericke University MagdeburgUniversitätsplatz 239106MagdeburgGermany
| | - Michael Mauksch
- Computer Chemistry CenterFriedrich-Alexander University of Erlangen-NürnbergNägelsbachstrasse 25a91052ErlangenGermany
| | - Andreas Seidel‐Morgenstern
- Max Planck Institute for Dynamics of Complex Technical SystemsSandtorstraße 139106MagdeburgGermany
- Otto von Guericke University MagdeburgUniversitätsplatz 239106MagdeburgGermany
| | - Heike Lorenz
- Max Planck Institute for Dynamics of Complex Technical SystemsSandtorstraße 139106MagdeburgGermany
| | - Svetlana B. Tsogoeva
- Organic Chemistry Chair I and Interdisciplinary Center for Molecular Materials (ICMM)Friedrich-Alexander University of Erlangen-NürnbergNikolaus-Fiebiger-Strasse 1091058ErlangenGermany
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Mirror Symmetry Breaking in Liquids and Their Impact on the Development of Homochirality in Abiogenesis: Emerging Proto-RNA as Source of Biochirality? Symmetry (Basel) 2020. [DOI: 10.3390/sym12071098] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Recent progress in mirror symmetry breaking and chirality amplification in isotropic liquids and liquid crystalline cubic phases of achiral molecule is reviewed and discussed with respect to its implications for the hypothesis of emergence of biological chirality. It is shown that mirror symmetry breaking takes place in fluid systems where homochiral interactions are preferred over heterochiral and a dynamic network structure leads to chirality synchronization if the enantiomerization barrier is sufficiently low, i.e., that racemization drives the development of uniform chirality. Local mirror symmetry breaking leads to conglomerate formation. Total mirror symmetry breaking requires either a proper phase transitions kinetics or minor chiral fields, leading to stochastic and deterministic homochirality, respectively, associated with an extreme chirality amplification power close to the bifurcation point. These mirror symmetry broken liquids are thermodynamically stable states and considered as possible systems in which uniform biochirality could have emerged. A model is hypothesized, which assumes the emergence of uniform chirality by chirality synchronization in dynamic “helical network fluids” followed by polymerization, fixing the chirality and leading to proto-RNA formation in a single process.
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