51
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A Quantum-Chemical DFT Approach to Elucidation of the Chirality Transfer Mechanism of the Enantioselective Suzuki–Miyaura Cross-Coupling Reaction. J CHEM-NY 2017. [DOI: 10.1155/2017/3617527] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The DFT calculations of the simplified model of the asymmetric Suzuki–Miyaura coupling reaction were performed at the M062x/LANL2DZ theory level at first. It was found that enantioselective reactions mediated by the palladium complexes of chiral C,P-ligands follow a four-stage mechanism similar to that proposed previously as one of the most credible mechanisms. It should be underlined that the presence of substituents in the substrates and the chiral ligand at ortho positions determines the energies of possible diastereoisomeric transition states and intermediates in initial reaction steps. This suggests that, in practice, a sharp selection of theoretically possible paths of chirality transfer from the catalyst to the product should have a place and, therefore, the absolute configuration of the formed atropisomeric product is defined and can be predicted.
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52
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Ryabchun A, Raguzin I, Stumpe J, Shibaev V, Bobrovsky A. Cholesteric Polymer Scaffolds Filled with Azobenzene-Containing Nematic Mixture with Phototunable Optical Properties. ACS APPLIED MATERIALS & INTERFACES 2016; 8:27227-27235. [PMID: 27633069 DOI: 10.1021/acsami.6b09642] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The past two decades witnessed tremendous progress in the field of creation of different types of responsive materials. Cholesteric polymer networks present a very promising class of smart materials due to the combination of the unique optical properties of cholesteric mesophase and high mechanical properties of polymer networks. In the present work we demonstrate the possibility of fast and reversible photocontrol of the optical properties of cholesteric polymer networks. Several cholesteric photopolymerizable mixtures are prepared, and porous cholesteric network films with different helix pitches are produced by polymerization of these mixtures. An effective and simple method of the introduction of photochromic azobenzene-containing nematic mixture capable of isothermal photoinducing the nematic-isotropic phase transition into the porous polymer matrix is developed. It is found that cross-linking density and degree of polymer network filling with a photochromic nematic mixture strongly influence the photo-optical behavior of the obtained composite films. In particular, the densely cross-linked films are characterized by a decrease in selective light reflection bandwidth, whereas weakly cross-linked systems display two processes: the shift of selective light reflection peak and decrease of its width. It is noteworthy that the obtained cholesteric materials are shown to be very promising for the variety applications in optoelectronics and photonics.
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Affiliation(s)
- Alexander Ryabchun
- Fraunhofer Institute for Applied Polymer Research , Geiselbergstrasse 69, 14476 Potsdam-Golm, Germany
- Chemistry Department, Moscow State University , Lenin Hills 1, 119991 Moscow, Russia
| | - Ivan Raguzin
- Leibniz Institute of Polymer Research , Hohe Strasse 6, 01069 Dresden, Germany
| | - Joachim Stumpe
- University of Potsdam , Am Mühlenberg 11, 14476 Potsdam, Germany
| | - Valery Shibaev
- Chemistry Department, Moscow State University , Lenin Hills 1, 119991 Moscow, Russia
| | - Alexey Bobrovsky
- Chemistry Department, Moscow State University , Lenin Hills 1, 119991 Moscow, Russia
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53
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Růžička Š, Wensink HH. Simulating the pitch sensitivity of twisted nematics of patchy rods. SOFT MATTER 2016; 12:5205-5213. [PMID: 27184814 DOI: 10.1039/c6sm00727a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Stiff, elongated biomolecules such as filamentous viruses, DNA or cellulose nanocrystals are known to form liquid crystals often exhibiting a helical supramolecular organization. Little is known about the microscopic origin, size and handedness of the helical pitch in these, so-called cholesteric phases. Experimental observations in chiral lyotropics suggest that long-ranged chiral forces of electrostatic origin acting between the mesogens are responsible for such organization. Using large-scale computer simulation we study the sensitivity of the pitch imparted by soft microscopic helices and confirm that the helical sense is sensitive to a change of packing fraction, magnitude of the molecular pitch and amplitude of the chiral interactions. In particular, we find evidence that the cholesteric helix sense may change spontaneously upon variation of particle density, at fixed molecular chirality. These pitch inversions have been reported in recent theoretical studies but simulation evidence remains elusive. We rationalize these sudden changes in the supramolecular helical symmetry on the basis of detailed measurements of the mean-torque generated by the twisting of the helices. The simulation methodology employed does not require confining the twisted nematic in a slab geometry and allows for a simultaneous measurement of the pitch and the twist elastic constant. We find that the twist elastic constant increases almost linearly with density suggesting that twisted nematic shows no signs of anomalous stiffening due to pre-smectic fluctuations at higher packing fraction.
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Affiliation(s)
- Štěpán Růžička
- Laboratoire de Physique des Solides, CNRS, Université Paris-Sud, Université Paris-Saclay, UMR 8502 - 91405 Orsay Cedex, France.
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54
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Bisoyi HK, Li Q. Light‐Directed Dynamic Chirality Inversion in Functional Self‐Organized Helical Superstructures. Angew Chem Int Ed Engl 2016; 55:2994-3010. [DOI: 10.1002/anie.201505520] [Citation(s) in RCA: 190] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 08/10/2015] [Indexed: 12/13/2022]
Affiliation(s)
- Hari Krishna Bisoyi
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State University Kent OH 44242 USA
| | - Quan Li
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State University Kent OH 44242 USA
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55
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Bisoyi HK, Li Q. Lichtgesteuerte dynamische Chiralitätsumkehr in funktionalen selbstorganisierten helikalen Überstrukturen. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201505520] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Hari Krishna Bisoyi
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State University Kent OH 44242 USA
| | - Quan Li
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program Kent State University Kent OH 44242 USA
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56
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Vlatković M, Feringa BL, Wezenberg SJ. Dynamic Inversion of Stereoselective Phosphate Binding to a Bisurea Receptor Controlled by Light and Heat. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201509479] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Matea Vlatković
- Stratingh Institute for Chemistry; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Ben L. Feringa
- Stratingh Institute for Chemistry; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Sander J. Wezenberg
- Stratingh Institute for Chemistry; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
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57
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Vlatković M, Feringa BL, Wezenberg SJ. Dynamic Inversion of Stereoselective Phosphate Binding to a Bisurea Receptor Controlled by Light and Heat. Angew Chem Int Ed Engl 2015; 55:1001-4. [DOI: 10.1002/anie.201509479] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Matea Vlatković
- Stratingh Institute for Chemistry; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Ben L. Feringa
- Stratingh Institute for Chemistry; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Sander J. Wezenberg
- Stratingh Institute for Chemistry; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
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58
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Lee YH, Wang L, Yang H, Wu ST. Photo-induced handedness inversion with opposite-handed cholesteric liquid crystal. OPTICS EXPRESS 2015; 23:22658-22666. [PMID: 26368234 DOI: 10.1364/oe.23.022658] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Cholesteric liquid crystals (CLCs) are self-organized helical nano-structures that selectively reflect certain wavelength of a circularly polarized light. For most CLCs, the handedness is fixed once a chiral dopant is employed. Here, we report a handedness-invertible CLC through opposite-handed doping of a photo-sensitive chiral azobenzene dopant and a photo-stable chiral dopant. With high solubility of the photo-sensitive chiral dopant, the Bragg reflection can be tailored from right-handed to left-handed upon UV exposure. The reversed process can be easily carried out through heating.
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59
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Orlova T, Aßhoff SJ, Yamaguchi T, Katsonis N, Brasselet E. Creation and manipulation of topological states in chiral nematic microspheres. Nat Commun 2015; 6:7603. [PMID: 26145716 PMCID: PMC4506501 DOI: 10.1038/ncomms8603] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 05/25/2015] [Indexed: 12/26/2022] Open
Abstract
Topology is a universal concept that is encountered in daily life and is known to determine many static and dynamical properties of matter. Taming and controlling the topology of materials therefore constitutes a contemporary interdisciplinary challenge. Building on the controllable spatial properties of soft matter appears as a relevant strategy to address the challenge, in particular, because it may lead to paradigmatic model systems that allow checking theories experimentally. Here we report experimentally on a wealth of complex free-standing metastable topological architectures at the micron scale, in frustrated chiral nematic droplets. These results support recent works predicting the formation of free-standing knotted and linked disclination structures in confined chiral nematic fluids. We also demonstrate that various kinds of external fields (thermal, electrical and optical) can be used to achieve topological remote control. All this may foster the development of new devices based on topologically structured soft media.
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Affiliation(s)
- Tetiana Orlova
- Laboratoire Ondes et Matière d'Aquitaine, University of Bordeaux, CNRS, 351 cours de la Libération, Talence F-33400, France
| | - Sarah Jane Aßhoff
- Laboratory for Biomolecular Nanotechnology, MESA+ Institute for Nanotechnology, University of Twente, PO Box 207, Enschede 7500AE, The Netherlands
| | - Tadatsugu Yamaguchi
- Laboratory for Biomolecular Nanotechnology, MESA+ Institute for Nanotechnology, University of Twente, PO Box 207, Enschede 7500AE, The Netherlands
| | - Nathalie Katsonis
- Laboratory for Biomolecular Nanotechnology, MESA+ Institute for Nanotechnology, University of Twente, PO Box 207, Enschede 7500AE, The Netherlands
| | - Etienne Brasselet
- Laboratoire Ondes et Matière d'Aquitaine, University of Bordeaux, CNRS, 351 cours de la Libération, Talence F-33400, France
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60
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Wang L, Dong H, Li Y, Liu R, Wang YF, Bisoyi HK, Sun LD, Yan CH, Li Q. Luminescence-driven reversible handedness inversion of self-organized helical superstructures enabled by a novel near-infrared light nanotransducer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2015; 27:2065-9. [PMID: 25675908 DOI: 10.1002/adma.201405690] [Citation(s) in RCA: 137] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 01/09/2015] [Indexed: 05/27/2023]
Abstract
Nanotransducer-impregnated self-organized helical superstructures are found to exhibit unprecedented reversible handedness inversion upon irradiation by the dual-wavelength near-infrared light. Upon near-infrared laser irradiation at 808 nm, the helical twist sense changes from right-handed to left-handed through an achiral liquid-crystal phase, whereas its reverse process occurs upon the near-infrared laser irradiation at 980 nm.
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Affiliation(s)
- Ling Wang
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH, 44242, USA
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61
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Dussi S, Belli S, van Roij R, Dijkstra M. Cholesterics of colloidal helices: Predicting the macroscopic pitch from the particle shape and thermodynamic state. J Chem Phys 2015; 142:074905. [DOI: 10.1063/1.4908162] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Simone Dussi
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Simone Belli
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
| | - René van Roij
- Institute for Theoretical Physics, Center for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
| | - Marjolein Dijkstra
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
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Ryabchun A, Bobrovsky A, Gritsai Y, Sakhno O, Shibaev V, Stumpe J. Stable selective gratings in LC polymer by photoinduced helix pitch modulation. ACS APPLIED MATERIALS & INTERFACES 2015; 7:2554-2560. [PMID: 25541812 DOI: 10.1021/am507499p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A cholesteric mixture based on the nematic liquid crystalline side-chain polymer doped with a chiral-photochromic compound was prepared and used as an active medium for creation of stable polarization selective gratings by phototunable modulation of the helix pitch. Such modulation was fabricated in the polymer mixture by a nonpolarized UV-irradiation with spatially modulated intensity that causes E-Z isomerization of a chiral-photochromic dopant, decreasing its helical twisting power. It was shown that the gratings recorded by UV-exposure through a mask are strongly selective to the handedness of circular polarized light. The studied polymer film forms a right-handed helical structure and, correspondingly, the diffraction of only the right-circularly polarized light was found in the transmittance mode. The maximum diffraction efficiencies were found for the wavelength values between the maxima of selective light reflection. The films obtained open very interesting possibilities for further development of materials with stable gratings operating in the entire visible spectral range. Both the position and the width of the spectral range of an efficient diffraction can be easily controlled by the UV exposure and concentration of the dopant. The materials obtained and methods developed can be used for creation of specific diffraction elements for optics and photonics.
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Affiliation(s)
- Alexander Ryabchun
- Fraunhofer Institute for Applied Polymer Research , Geiselbergstr. 69, Potsdam/Golm, 14476 Germany
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63
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Matt B, Pondman KM, Asshoff SJ, Ten Haken B, Fleury B, Katsonis N. Soft magnets from the self-organization of magnetic nanoparticles in twisted liquid crystals. Angew Chem Int Ed Engl 2014; 53:12446-50. [PMID: 25196652 DOI: 10.1002/anie.201404312] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 06/25/2014] [Indexed: 11/06/2022]
Abstract
Organizing magnetic nanoparticles into long-range and dynamic assemblies would not only provide new insights into physical phenomena but also open opportunities for a wide spectrum of applications. In particular, a major challenge consists of the development of nanoparticle-based materials for which the remnant magnetization and coercive field can be controlled at room temperature. Our approach consists of promoting the self-organization of magnetic nanoparticles in liquid crystals (LCs). Using liquid crystals as organizing templates allows us to envision the design of tunable self-assemblies of magnetic nanoparticles, because liquid crystals are known to reorganize under a variety of external stimuli. Herein, we show that twisted liquid crystals can be used as efficient anisotropic templates for superparamagnetic nanoparticles and demonstrate the formation of hybrid soft magnets at room temperature.
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Affiliation(s)
- Benjamin Matt
- MESA+ Institute for Nanotechnology (BNT), University of Twente, PO Box 207, 7500 AE Enschede (The Netherlands)
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64
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Bisoyi HK, Li Q. Light-directing chiral liquid crystal nanostructures: from 1D to 3D. Acc Chem Res 2014; 47:3184-95. [PMID: 25181560 DOI: 10.1021/ar500249k] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Endowing external, remote, and dynamic control to self-organized superstructures with desired functionalities is a principal driving force in the bottom-up nanofabrication of molecular devices. Light-driven chiral molecular switches or motors in liquid crystal (LC) media capable of self-organizing into optically tunable one-dimensional (1D) and three-dimensional (3D) superstructures represent such an elegant system. As a consequence, photoresponsive cholesteric LCs (CLCs), i.e., self-organized 1D helical superstructures, and LC blue phases (BPs), i.e., self-organized 3D periodic cubic lattices, are emerging as a new generation of multifunctional supramolecular 1D and 3D photonic materials in their own right because of their fundamental academic interest and technological significance. These smart stimuli-responsive materials can be facilely fabricated from achiral LC hosts by the addition of a small amount of a light-driven chiral molecular switch or motor. The photoresponsiveness of these materials is a result of both molecular interaction and geometry changes in the chiral molecular switch upon light irradiation. The doped photoresponsive CLCs undergo light-driven pitch modulation and/or helix inversion, which has many applications in color filters, polarizers, all-optical displays, optical lasers, sensors, energy-saving smart devices, and so on. Recently, we have conceptualized and rationally synthesized different light-driven chiral molecular switches that have very high helical twisting powers (HTPs) and exhibit large changes in HTP in different states, thereby enabling wide phototunability of the systems by the addition of very small amounts of the molecular switches into commercially available achiral LCs. The light-driven chiral molecular switches are based on well-recognized azobenzene, dithienylcyclopentene, and spirooxazine derivatives. We have demonstrated high-resolution and lightweight photoaddressable displays without patterned electronics on flexible substrates. The wide tunability of the HTP furnishes reflection colors encompassing the whole visible spectrum and beyond in a reversible manner. Photomodulation of the helical pitch of the CLCs has been achieved by UV, visible, and near-infrared (NIR) light irradiation. NIR-light-induced red, green, and blue (RGB) reflections have been leveraged only by varying the power density of the IR laser. Some chiral switches are found to confer helix inversion to the cholesteric systems, which qualifies the CLCs for applications where circularly polarized light is involved. Dynamic and static primary RGB reflection colors have been achieved in a single film. LC BPs have been fabricated and investigated in the context of self-organized 3D photonic band gap (PBG) materials, and dynamic phototuning of the PBG over the visible region has been achieved. Omnidirectional lasing and tuning of the laser emission wavelength have also been attained in monodisperse photoresponsive CLC microshells fabricated by a capillary-based microfluidic technique. This Account covers the research and development in our laboratory starting from the design concepts and synthesis of photodynamic chiral molecular switches to their applications in the fabrication of photoresponsive CLCs and BPs. Potential and demonstrated practical applications of photoresponsive CLCs, microshells, and BPs are discussed, and the Account concludes with a brief forecast of what lies beyond the horizon in this rapidly expanding and fascinating field.
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Affiliation(s)
- Hari Krishna Bisoyi
- Liquid Crystal
Institute
and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, United States
| | - Quan Li
- Liquid Crystal
Institute
and Chemical Physics Interdisciplinary Program, Kent State University, Kent, Ohio 44242, United States
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65
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Matt B, Pondman KM, Asshoff SJ, ten Haken B, Fleury B, Katsonis N. Soft Magnets from the Self-Organization of Magnetic Nanoparticles in Twisted Liquid Crystals. Angew Chem Int Ed Engl 2014. [DOI: 10.1002/ange.201404312] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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66
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67
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Frezza E, Ferrarini A, Bindu Kolli H, Giacometti A, Cinacchi G. Left or right cholesterics? A matter of helix handedness and curliness. Phys Chem Chem Phys 2014; 16:16225-32. [DOI: 10.1039/c4cp01816h] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Using an Onsager-like theory, we have investigated the relationship between the morphology of hard helical particles and the features (pitch and handedness) of the cholesteric phase that they form.
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Affiliation(s)
- Elisa Frezza
- Dipartimento di Scienze Chimiche
- Università di Padova
- 35131 Padova, Italy
| | - Alberta Ferrarini
- Dipartimento di Scienze Chimiche
- Università di Padova
- 35131 Padova, Italy
| | - Hima Bindu Kolli
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- 30123 Venezia, Italy
| | - Achille Giacometti
- Dipartimento di Scienze Molecolari e Nanosistemi
- Università Ca' Foscari di Venezia
- 30123 Venezia, Italy
| | - Giorgio Cinacchi
- Departamento de Física Teórica de la Materia Condensada and Instituto de Física de la Materia Condensada
- Universidad Autónoma de Madrid
- Campus de Cantoblanco
- 28049 Madrid, Spain
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68
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Li Y, Xue C, Wang M, Urbas A, Li Q. Photodynamic chiral molecular switches with thermal stability: from reflection wavelength tuning to handedness inversion of self-organized helical superstructures. Angew Chem Int Ed Engl 2013; 52:13703-7. [PMID: 24150899 DOI: 10.1002/anie.201306396] [Citation(s) in RCA: 115] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Indexed: 11/10/2022]
Abstract
A good turn: Three compounds that bear two axially chiral bridged binaphthyl units were developed as photodynamic chiral dopants for nematic liquid crystals. For compounds with suitable bridge lengths, a change in the dihedral angle induced a switch of the binaphthyl units from the cisoid to the transoid form upon UV irradiation, which led to an inversion of the handedness of the helices.
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Affiliation(s)
- Yannian Li
- Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242 (USA)
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69
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Li Y, Xue C, Wang M, Urbas A, Li Q. Photodynamic Chiral Molecular Switches with Thermal Stability: From Reflection Wavelength Tuning to Handedness Inversion of Self-Organized Helical Superstructures. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201306396] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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70
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Li Y, Wang M, White TJ, Bunning TJ, Li Q. Azoarenes with Opposite Chiral Configurations: Light-Driven Reversible Handedness Inversion in Self-Organized Helical Superstructures. Angew Chem Int Ed Engl 2013; 52:8925-9. [DOI: 10.1002/anie.201303786] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Indexed: 11/10/2022]
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71
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Li Y, Wang M, White TJ, Bunning TJ, Li Q. Azoarenes with Opposite Chiral Configurations: Light-Driven Reversible Handedness Inversion in Self-Organized Helical Superstructures. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201303786] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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72
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Pietropaolo A, Nakano T. Molecular mechanism of polyacrylate helix sense switching across its free energy landscape. J Am Chem Soc 2013; 135:5509-12. [PMID: 23551335 DOI: 10.1021/ja4002508] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Helical polymers with switchable screw sense are versatile frameworks for chiral functional materials. In this work, we reconstructed the free energy landscape of helical poly(2,7-bis(4-tert-butylphenyl)fluoren-9-yl acrylate) [poly(BBPFA)], as its racemization is selectively driven by light without any rearrangement of chemical bonds. The chirality inversion was enforced by atomistic free energy simulations using chirality indices as reaction coordinates. The free energy landscape reproduced the experimental electronic circular dichroism spectra. We propose that the chirality inversion of poly(BBPFA) proceeds from a left-handed 31 helix via multistate free energy pathways to reach the right-handed 31 helix. The inversion is triggered by the rotation of biphenyl units with an activation barrier of 38 kcal/mol. To the best of our knowledge, this is the first report on the chiral inversion mechanism of a helical polymer determined in a quantitative way in the framework of atomistic free energy simulations.
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Affiliation(s)
- Adriana Pietropaolo
- Dipartimento di Scienze della Salute, Università di Catanzaro, Viale Europa, 88100 Catanzaro, Italy.
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73
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Rossi M, Zanchetta G, Klussmann S, Clark NA, Bellini T. Propagation of chirality in mixtures of natural and enantiomeric DNA oligomers. PHYSICAL REVIEW LETTERS 2013; 110:107801. [PMID: 23521299 DOI: 10.1103/physrevlett.110.107801] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Indexed: 06/01/2023]
Abstract
Concentrated solutions of ultrashort duplex-forming DNA oligomers may develop various forms of liquid crystal ordering among which is the chiral nematic phase, characterized by a macroscopic helical precession of molecular orientation. The specifics of how chirality propagates from the molecular to the mesoscale is still unclear, both in general and in the case of DNA-based liquid crystals. We have here investigated the onset of nematic ordering and its chiral character in mixtures of natural D-DNA oligomers forming right-handed duplex helices and of mirror symmetric (L-DNA) molecules, forming left-handed helices. Since the nematic ordering of DNA duplexes is mediated by their end-to-end aggregation into linear columns, by controlling the terminals of both enantiomers we could study the propagation of chirality in solutions where the D and L species form mixtures of homochiral columns, and in solutions of heterochiral columns. The two systems behave in markedly different fashion. By adopting a simple model based on nearest-neighbor interactions, we account for the different observed dependence of the chirality of these two systems on the enantiomeric ratio.
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Affiliation(s)
- Marina Rossi
- Dipartimento di Biotecnologie Mediche e Medicina Traslazionale, Università degli Studi di Milano, via Fratelli Cervi 93, I-20090 Segrate, MI, Italy
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Wezenberg SJ, Ferroni F, Pieraccini S, Schweizer WB, Ferrarini A, Spada GP, Diederich F. Effective cholesteric liquid crystal inducers based on axially chiral alleno-acetylenes. RSC Adv 2013. [DOI: 10.1039/c3ra44883e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Asshoff SJ, Iamsaard S, Bosco A, Cornelissen JJLM, Feringa BL, Katsonis N. Time-programmed helix inversion in phototunable liquid crystals. Chem Commun (Camb) 2012; 49:4256-8. [PMID: 23230570 DOI: 10.1039/c2cc37161h] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Doping cholesteric liquid crystals with photo-responsive molecules enables controlling the colour and polarisation of the light they reflect. However, accelerating the rate of relaxation of these photo-controllable liquid crystals remains challenging. Here we show that the relaxation rate of the cholesteric helix is fully determined by helix inversion of the molecular dopants.
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Affiliation(s)
- Sarah J Asshoff
- Laboratory for Biomolecular Nanotechnology, MESA+ Institute for Nanotechnology, University of Twente, PO Box 207, 7500 AE Enschede, The Netherlands
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Ito H, Tsukube H, Shinoda S. A chirality rewriting cycle mediated by a dynamic cyclen–calcium complex. Chem Commun (Camb) 2012; 48:10954-6. [DOI: 10.1039/c2cc35350d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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