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Dorn RW, Wall BJ, Ference SB, Norris SR, Lubach JW, Rossini AJ, VanVeller B. Attached Nitrogen Test by 13C- 14N Solid-State NMR Spectroscopy for the Structure Determination of Heterocyclic Isomers. Org Lett 2022; 24:5635-5640. [PMID: 35731042 PMCID: PMC9933616 DOI: 10.1021/acs.orglett.2c01576] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Differentiation of heterocyclic isomers by solution 1H, 13C, and 15N NMR spectroscopy is often challenging due to similarities in their spectroscopic signatures. Here, 13C{14N} solid-state NMR spectroscopy experiments are shown to operate as an "attached nitrogen test", where heterocyclic isomers are easy to distinguish based on one-dimensional nitrogen-filtered 13C solid-state NMR. We anticipate that these NMR experiments will facilitate the assignment of heterocyclic isomers during synthesis and natural product discovery.
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Affiliation(s)
- Rick W. Dorn
- Iowa State University, Department of Chemistry, Ames, IA, USA, 50011.,US Department of Energy, Ames Laboratory, Ames, IS, USA, 50011
| | - Brendan J. Wall
- Iowa State University, Department of Chemistry, Ames, IA, USA, 50011
| | - Sarah B. Ference
- Iowa State University, Department of Chemistry, Ames, IA, USA, 50011
| | - Sean R. Norris
- Iowa State University, Department of Chemistry, Ames, IA, USA, 50011
| | | | - Aaron J. Rossini
- Iowa State University, Department of Chemistry, Ames, IA, USA, 50011.,US Department of Energy, Ames Laboratory, Ames, IS, USA, 50011.,Corresponding Author, 515-294-8952 , 515-294-7613
| | - Brett VanVeller
- Iowa State University, Department of Chemistry, Ames, IA, USA, 50011.,Corresponding Author, 515-294-8952 , 515-294-7613
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van der Wel PCA. Dihedral Angle Measurements for Structure Determination by Biomolecular Solid-State NMR Spectroscopy. Front Mol Biosci 2021; 8:791090. [PMID: 34938776 PMCID: PMC8685456 DOI: 10.3389/fmolb.2021.791090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 11/22/2021] [Indexed: 11/13/2022] Open
Abstract
In structural studies of immobilized, aggregated and self-assembled biomolecules, solid-state NMR (ssNMR) spectroscopy can provide valuable high-resolution structural information. Among the structural restraints provided by magic angle spinning (MAS) ssNMR the canonical focus is on inter-atomic distance measurements. In the current review, we examine the utility of ssNMR measurements of angular constraints, as a complement to distance-based structure determination. The focus is on direct measurements of angular restraints via the judicious recoupling of multiple anisotropic ssNMR parameters, such as dipolar couplings and chemical shift anisotropies. Recent applications are highlighted, with a focus on studies of nanocrystalline polypeptides, aggregated peptides and proteins, receptor-substrate interactions, and small molecule interactions with amyloid protein fibrils. The review also examines considerations of when and where ssNMR torsion angle experiments are (most) effective, and discusses challenges and opportunities for future applications.
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Affiliation(s)
- Patrick C. A. van der Wel
- Solid-state NMR Group, Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
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Tang D, Shao C, Jiang S, Sun C, Song S. Graphitic C 2N 3: An Allotrope of g-C 3N 4 Containing Active Azide Pentagons as Metal-Free Photocatalyst for Abundant H 2 Bubble Evolution. ACS NANO 2021; 15:7208-7215. [PMID: 33871961 DOI: 10.1021/acsnano.1c00477] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
A g-C3N4 allotrope, a curved leaf-like graphitic C2N3 (g-C2N3) with an intrinsic spontaneous polarization electric field (ISPEF), has been constructed for efficient solar energy conversion into H2 energy via photocatalytic H2O splitting. The curved leaf-like π-delocalization g-C2N3 was composed of aromatic azide pentagons and normal triazine hexagons obtained by cycloaddition between -C≡N groups from dicyandiamide polymerization and azide from the heat-treated polypyrrole fibers. Under light irradiation (λ > 420 nm), photo-generated charges are driven to separate efficiently and transfer from bulk to active sites of the surface under ISPEF that is opposite to the Coulomb field. Consequently, without any cocatalyst, g-C3N4 allotrope demonstrates a very high H2-production activity of 14.9 mmol g-1 h-1 accompanied by a lot of H2 bubbles, which is 2.6 times of g-C3N4 loading with Pt. In comparison with the reported metal-free photocatalysts or those supported with noble metals, g-C3N4 allotrope (i.e., leaf-like g-C2N3) is confirmed to be the best metal-free photocatalyst for H2O splitting into H2 fuel so far. The contructed leaf-like g-C2N3 with SPEF supplies a suitable platform for solar energy conversion into H2 fuel, which actively contributes to clean energy production.
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Affiliation(s)
- Dongmei Tang
- School of Material Science and Chemical Engineering, Ningbo University, Fenghua Road 818, Ningbo 315211, People's Republic of China
| | - Chengtian Shao
- Department of Chemistry, Chung Yuan Christian University, Taoyuan City 32033, Taiwan
| | - Shujuan Jiang
- School of Material Science and Chemical Engineering, Ningbo University, Fenghua Road 818, Ningbo 315211, People's Republic of China
| | - Chuanzhi Sun
- College of Chemistry, Chemical Engineering and Materials Science, Shandong Provincial Key Laboratory of Clean Production of Fine Chemicals, Shandong Normal University, Jinan 250014, People's Republic of China
| | - Shaoqing Song
- School of Material Science and Chemical Engineering, Ningbo University, Fenghua Road 818, Ningbo 315211, People's Republic of China
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Hodgkinson P. NMR crystallography of molecular organics. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 118-119:10-53. [PMID: 32883448 DOI: 10.1016/j.pnmrs.2020.03.001] [Citation(s) in RCA: 70] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 02/25/2020] [Accepted: 03/13/2020] [Indexed: 06/11/2023]
Abstract
Developments of NMR methodology to characterise the structures of molecular organic structures are reviewed, concentrating on the previous decade of research in which density functional theory-based calculations of NMR parameters in periodic solids have become widespread. With a focus on demonstrating the new structural insights provided, it is shown how "NMR crystallography" has been used in a spectrum of applications from resolving ambiguities in diffraction-derived structures (such as hydrogen atom positioning) to deriving complete structures in the absence of diffraction data. As well as comprehensively reviewing applications, the different aspects of the experimental and computational techniques used in NMR crystallography are surveyed. NMR crystallography is seen to be a rapidly maturing subject area that is increasingly appreciated by the wider crystallographic community.
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Affiliation(s)
- Paul Hodgkinson
- Department of Chemistry, Durham University, Stockton Road, Durham DH1 3LE, UK.
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