Effortless Extraction of Structural and Orientational Information from 13C-1H Dipolar Couplings for Thiophene Mesogens
Five molecular mesogens containing phenyl rings and thiophene are subjected to a detailed 13C NMR investigation. The first mesogen contains only phenyl rings, while the other four have thiophene with substitution at position 2 or 3. Two of these also have a spacer inserted between the thiophene and the rest of the core unit. The mesophase properties evaluated by complementary techniques reveal an enantiotropic nematic phase for all the cases and smectic C as well as Crystal J for a few mesogens. In addition to solution 13C NMR, the samples were studied using 1D and 2D solid-state 13C NMR experiments in the liquid crystalline phase. The chemical shifts and 13C-1H dipolar couplings obtained in the mesophase provided cutting-edge information about the molecular structure and orientation of the thiophene mesogens. Accordingly, dramatic differences in these parameters are noted for the mesogens, and consequently, the identification of 2- and 3-substituted thiophene mesogens is accomplished by a simple visual examination of the 2D spectra. Furthermore, for mesogens with a spacer between thiophene and the rest of the core, 13C chemical shifts and 13C-1H dipolar couplings showed remarkable variation, which was directly reflected in the order parameters. For instance, the order parameter (Szz) of thiophene in 2- and 3-substituted mesogens in which the spacer is absent is ∼0.63 whereas for those with spacer, it is reduced to ∼0.14-0.18. In comparison, the mesogen in which the core unit is made up of phenyl rings alone that is used to benchmark the characteristics of thiophene ordering showed an order parameter of ∼0.85. The study unambiguously demonstrates the supremacy of 13C NMR in extracting the structural and orientational information on mesogens in which thiophene is a constituent of the core unit.
| Medienart: |
E-Artikel |
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| Erscheinungsjahr: |
2023 |
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| Erschienen: |
2023 |
| Enthalten in: |
Zur Gesamtaufnahme - year:2023 |
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| Enthalten in: |
The journal of physical chemistry. B - (2023) vom: 08. Dez. |
| Sprache: |
Englisch |
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| Beteiligte Personen: |
Veeraprakash, Bathini [VerfasserIn] |
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| Anmerkungen: |
Date Revised 08.12.2023 published: Print-Electronic Citation Status Publisher |
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| doi: |
10.1021/acs.jpcb.3c06176 |
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| funding: |
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| Förderinstitution / Projekttitel: |
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| PPN (Katalog-ID): |
NLM365542369 |
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| 245 | 1 | 0 | |a Effortless Extraction of Structural and Orientational Information from 13C-1H Dipolar Couplings for Thiophene Mesogens |
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| 500 | |a Date Revised 08.12.2023 | ||
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| 520 | |a Five molecular mesogens containing phenyl rings and thiophene are subjected to a detailed 13C NMR investigation. The first mesogen contains only phenyl rings, while the other four have thiophene with substitution at position 2 or 3. Two of these also have a spacer inserted between the thiophene and the rest of the core unit. The mesophase properties evaluated by complementary techniques reveal an enantiotropic nematic phase for all the cases and smectic C as well as Crystal J for a few mesogens. In addition to solution 13C NMR, the samples were studied using 1D and 2D solid-state 13C NMR experiments in the liquid crystalline phase. The chemical shifts and 13C-1H dipolar couplings obtained in the mesophase provided cutting-edge information about the molecular structure and orientation of the thiophene mesogens. Accordingly, dramatic differences in these parameters are noted for the mesogens, and consequently, the identification of 2- and 3-substituted thiophene mesogens is accomplished by a simple visual examination of the 2D spectra. Furthermore, for mesogens with a spacer between thiophene and the rest of the core, 13C chemical shifts and 13C-1H dipolar couplings showed remarkable variation, which was directly reflected in the order parameters. For instance, the order parameter (Szz) of thiophene in 2- and 3-substituted mesogens in which the spacer is absent is ∼0.63 whereas for those with spacer, it is reduced to ∼0.14-0.18. In comparison, the mesogen in which the core unit is made up of phenyl rings alone that is used to benchmark the characteristics of thiophene ordering showed an order parameter of ∼0.85. The study unambiguously demonstrates the supremacy of 13C NMR in extracting the structural and orientational information on mesogens in which thiophene is a constituent of the core unit | ||
| 650 | 4 | |a Journal Article | |
| 700 | 1 | |a Kesava Reddy, Malireddygari |e verfasserin |4 aut | |
| 700 | 1 | |a Das, Bibhuti B |e verfasserin |4 aut | |
| 700 | 1 | |a Lobo, Nitin P |e verfasserin |4 aut | |
| 700 | 1 | |a Ramanathan, Krishna V |e verfasserin |4 aut | |
| 700 | 1 | |a Narasimhaswamy, Tanneru |e verfasserin |4 aut | |
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| 856 | 4 | 0 | |u http://dx.doi.org/10.1021/acs.jpcb.3c06176 |3 Volltext |
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