1
|
Martínez D, Schlossarek T, Würthner F, Soberats B. Isothermal Phase Transitions in Liquid Crystals Driven by Dynamic Covalent Chemistry. Angew Chem Int Ed Engl 2024; 63:e202403910. [PMID: 38635375 DOI: 10.1002/anie.202403910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 04/18/2024] [Accepted: 04/18/2024] [Indexed: 04/20/2024]
Abstract
The dynamic nature of calamitic liquid crystals is exploited to perform isothermal phase transitions driven by dynamic covalent chemistry. For this purpose, nematic (N) arrays based on aldehyde 1 were treated with different amines (A-E) in an on-surface process, which resulted in different isothermal phase transitions. These phase transformations were caused by in situ imination reactions and are dependent on the nature of the added amine. Transitions from the N to crystal (1A, 1E), isotropic (1B), and smectic (Sm) (1C, 1D) phases were achieved, while the resulting materials feature thermotropic liquid crystal behavior. A sequential transformation from the N 1 to the Sm 1C and then to the N 1B was achieved by coupling an imination to a transimination processes and adjusting the temperature. All of these processes were well characterized by microscopic, spectroscopic, and X-ray techniques, unlocking not only the constitutional but also the structural aspects of the phase transitions. This work provides new insights into designing constitutionally and structurally adaptable liquid crystal systems, paving the way toward the conception of programable evolutive pathways and adaptive materials.
Collapse
Affiliation(s)
- Daniel Martínez
- Department of Chemistry, Universitat de les Illes Balears, Cra. Valldemossa, Km. 7.5, 07122, Palma de Mallorca, Spain
| | - Tim Schlossarek
- Institut für Organische Chemie, Center for Nanosystems Chemistry (CNC), and Bavarian Polymer Institute (BPI), Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Frank Würthner
- Institut für Organische Chemie, Center for Nanosystems Chemistry (CNC), and Bavarian Polymer Institute (BPI), Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Bartolome Soberats
- Department of Chemistry, Universitat de les Illes Balears, Cra. Valldemossa, Km. 7.5, 07122, Palma de Mallorca, Spain
| |
Collapse
|
2
|
Wang Y, Li YX, Cseh L, Chen YX, Yang SG, Zeng X, Liu F, Hu W, Ungar G. Enantiomers Self-Sort into Separate Counter-Twisted Ribbons of the Fddd Liquid Crystal─Antiferrochirality and Parachirality. J Am Chem Soc 2023; 145:17443-17460. [PMID: 37523689 PMCID: PMC10416214 DOI: 10.1021/jacs.3c06164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Indexed: 08/02/2023]
Abstract
The recently discovered orthorhombic liquid crystal (LC) phase of symmetry Fddd is proving to be widespread. In this work, a chiral hydroxybutyrate linkage is inserted into the molecular core of hexacatenar rodlike compounds, containing a thienylfluorenone fluorophore. In addition to more usual tools, the methods used include grazing-incidence X-ray scattering, modulated differential scanning calorimetry (DSC), flash DSC with rates up to 6000 K/s, and chiro-optical spectroscopies using Mueller matrix method, plus conformational mapping. Although pure R and S enantiomers form only a strongly chiral hexagonal columnar LC phase (Colh*), the racemic mixture forms a highly ordered Fddd phase with 4 right- and 4 left-handed twisted ribbon-like columns traversing its large unit cell. In that structure, the two enantiomers locally deracemize and self-sort into the columns of their preferred chirality. The twisted ribbons in Fddd, with a 7.54 nm pitch, consist of stacked rafts, each containing ∼2 side-by-side molecules, the successive rafts rotated by 17°. In contrast, an analogous achiral compound forms only the columnar phase. The multiple methods used gave a comprehensive picture and helped in-depth understanding not only of the Fddd phase but also of the "parachiral" Colh* in pure enantiomers with irregular helicity, whose chirality is compared to the magnetization of a paramagnet in a field. Unusual short-range ordering effects are also described. An explanation of these phenomena is proposed based on conformational analysis. Surprisingly, the isotropic-columnar transition is extremely fast, completing within ∼20 ms. A clear effect of phase on UV-vis absorption and emission is observed.
Collapse
Affiliation(s)
- Yan Wang
- Shaanxi
International Research Centre for Soft Matter, State Key Laboratory
for Mechanical Behaviour of Materials, Xi’an
Jiaotong University, Xi’an 710049, China
| | - Ya-Xin Li
- School
of Chemistry and Chemical Engineering, Henan
University of Technology, Zhengzhou 450001, China
| | - Liliana Cseh
- Romanian
Academy, Coriolan Dragulescu Institute of Chemistry, Timisoara 300223, Romania
| | - Yong-Xuan Chen
- State
Key Laboratory of Coordinate Chemistry, School of Chemistry and Chemical
Engineering, Nanjing University, Nanjing 210093, China
| | - Shu-Gui Yang
- Shaanxi
International Research Centre for Soft Matter, State Key Laboratory
for Mechanical Behaviour of Materials, Xi’an
Jiaotong University, Xi’an 710049, China
| | - Xiangbing Zeng
- Department
of Materials Science and Engineering, University
of Sheffield, Sheffield S1 3JD, U.K.
| | - Feng Liu
- Shaanxi
International Research Centre for Soft Matter, State Key Laboratory
for Mechanical Behaviour of Materials, Xi’an
Jiaotong University, Xi’an 710049, China
| | - Wenbing Hu
- State
Key Laboratory of Coordinate Chemistry, School of Chemistry and Chemical
Engineering, Nanjing University, Nanjing 210093, China
| | - Goran Ungar
- Shaanxi
International Research Centre for Soft Matter, State Key Laboratory
for Mechanical Behaviour of Materials, Xi’an
Jiaotong University, Xi’an 710049, China
- Department
of Materials Science and Engineering, University
of Sheffield, Sheffield S1 3JD, U.K.
| |
Collapse
|
3
|
Hockey-Stick Polycatenars: Network formation and transition from one dimensional to three-dimensional liquid crystalline phases. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118613] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
4
|
Alaasar M, Cai X, Cao Y, Liu F. Transition from lamellar to nanostructure mesophases in azobenzene-based hockey-stick polycatenars. NEW J CHEM 2022. [DOI: 10.1039/d2nj03255d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Tuning from 1D to 3D mesophases by alkyl chain engineering. Multichain π-conjugated hockey-stick molecules form lamellar SmA and meso-structure Ia3̄d with continuous networks. The effect of the position of the central bent-core unit on helical self-assembly is discussed.
Collapse
Affiliation(s)
- Mohamed Alaasar
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, Kurt Mothes Str. 2, D-06120, Halle, Saale, Germany
- Department of Chemistry, Faculty of Science, Cairo University, Giza, Egypt
| | - Xiaoqian Cai
- 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
| | - 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
| | - 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
| |
Collapse
|
5
|
Reppe T, Poppe S, Cai X, Cao Y, Liu F, Tschierske C. Spontaneous mirror symmetry breaking in benzil-based soft crystalline, cubic liquid crystalline and isotropic liquid phases. Chem Sci 2020; 11:5902-5908. [PMID: 32874512 PMCID: PMC7446726 DOI: 10.1039/d0sc01396j] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 04/29/2020] [Indexed: 01/06/2023] Open
Abstract
Benzil (diphenylethane-1,2-dione), which is a long known example for an achiral molecule crystallizing in a chiral space group, can also show mirror symmetry breaking in the fluid state if it is suitably functionalized. For some of the new benzil derivatives even three different subsequent mirror symmetry broken soft matter states with a chiral conglomerate structure can be observed. One is an isotropic liquid, the second one a cubic liquid crystal with a complex network structure and the third is a soft crystalline solid. Chirality develops by helical self-assembly combined with dynamic network formation, thus allowing macroscopic chirality synchronization. These achiral molecules, combining a transiently chiral bent core with multiple alkyl chains, provide a unique link between the mirror symmetry breaking phenomena observed for polycatenar and bent-core mesogens. The homogeneously chiral networks are of interest for application as chiral materials, and as templates for chiral recognition, separation and enantioselective catalysis.
Collapse
Affiliation(s)
- Tino Reppe
- Institute of Chemistry , Martin Luther University Halle-Wittenberg , Kurt-Mothes-Straße 2 , 06120 Halle , Germany .
| | - Silvio Poppe
- Institute of Chemistry , Martin Luther University Halle-Wittenberg , Kurt-Mothes-Straße 2 , 06120 Halle , 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 .
| | - Yu Cao
- 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 .
| | - Carsten Tschierske
- Institute of Chemistry , Martin Luther University Halle-Wittenberg , Kurt-Mothes-Straße 2 , 06120 Halle , Germany .
| |
Collapse
|
6
|
Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry. CRYSTALS 2019. [DOI: 10.3390/cryst9030178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this work, we report a study of two thermotropic liquid crystalline samples showing a not common mesophase behavior. The samples, namely a di-benzyloxy biphenyl derivative labelled 9/2 RS/RS, and a bimesogenic liquid crystal labelled L1, show a direct transition between two isotropic phases followed, at lower temperatures, by the optically isotropic, 3D structured, cubic phase. These systems have been investigated by means of 1H NMR diffusometry and 1H NMR relaxometry in order to characterize their isotropic–isotropic’–cubic mesophase behavior, mainly on the dynamic point of view. In particular, the temperature trend of the self-diffusion coefficients measured for both samples allowed us to significantly distinguish between the two isotropic phases, while the temperature dependence of the 1H spin-lattice relaxation time (T1) did not show significant discontinuities at the isotropic–isotropic’ phase transition. A preliminary analysis of the frequency-dependence of 1H T1 at different temperatures gives information about the main motional processes active in the isotropic mesophases.
Collapse
|
7
|
Wolska JM, Topnani N, Gorecka E, Mieczkowski J, Pociecha D. Polycatenar Mesogens with Various Degree of Flexibility of Molecular Structure. Chemphyschem 2016; 17:2686-90. [DOI: 10.1002/cphc.201600330] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Joanna M. Wolska
- Department of Chemistry; Warsaw University; Pasteura 1 02-093 Warsaw Poland
| | - Neha Topnani
- Department of Chemistry; Warsaw University; Pasteura 1 02-093 Warsaw Poland
| | - Ewa Gorecka
- Department of Chemistry; Warsaw University; Pasteura 1 02-093 Warsaw Poland
| | - Jozef Mieczkowski
- Department of Chemistry; Warsaw University; Pasteura 1 02-093 Warsaw Poland
| | - Damian Pociecha
- Department of Chemistry; Warsaw University; Pasteura 1 02-093 Warsaw Poland
| |
Collapse
|