1
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Rehman Z, Franks WT, Nguyen B, Schmidt HF, Scrivens G, Brown SP. Discovering the Solid-State Secrets of Lorlatinib by NMR Crystallography: To Hydrogen Bond or not to Hydrogen Bond. J Pharm Sci 2023; 112:1915-1928. [PMID: 36868358 DOI: 10.1016/j.xphs.2023.02.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 02/22/2023] [Accepted: 02/22/2023] [Indexed: 03/05/2023]
Abstract
Lorlatinib is an active pharmaceutical ingredient (API) used in the treatment of lung cancer. Here, an NMR crystallography analysis is presented whereby the single-crystal X-ray diffraction structure (CSD: 2205098) determination is complemented by multinuclear (1H, 13C, 14/15N, 19F) magic-angle spinning (MAS) solid-state NMR and gauge-including projector augmented wave (GIPAW) calculation of NMR chemical shifts. Lorlatinib crystallises in the P21 space group, with two distinct molecules in the asymmetric unit cell, Z' = 2. Three of the four NH2 hydrogen atoms form intermolecular hydrogen bonds, N30-H…N15 between the two distinct molecules and N30-H…O2 between two equivalent molecules. This is reflected in one of the NH21H chemical shifts being significantly lower, 4.0 ppm compared to 7.0 ppm. Two-dimensional 1H-13C, 14N-1H and 1H (double-quantum, DQ)-1H (single-quantum, SQ) MAS NMR spectra are presented. The 1H resonances are assigned and specific HH proximities corresponding to the observed DQ peaks are identified. The resolution enhancement at a 1H Larmor frequency of 1 GHz as compared to 500 or 600 MHz is demonstrated.
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Affiliation(s)
- Zainab Rehman
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | - W Trent Franks
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK
| | | | | | | | - Steven P Brown
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK.
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2
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Pawlak T, Paluch P, Dolot R, Bujacz G, Potrzebowski MJ. New salts of teriflunomide (TFM) - Single crystal X-ray and solid state NMR investigation. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2022; 122:101820. [PMID: 36067621 DOI: 10.1016/j.ssnmr.2022.101820] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/02/2022] [Accepted: 08/09/2022] [Indexed: 06/15/2023]
Abstract
New salts of teriflunomide TFM (drug approved for Multiple Sclerosis treatment) with inorganic counterions: lithium (TFM_Li), sodium (TFM_Na), potassium (TFM_K), rubidium (TFM_Rb), caesium (TFM_Cs) and ammonium (TFM_NH4) were prepared and investigated employing solid state NMR Spectroscopy, Powder X-ray Diffraction PXRD and Single Crystal X-ray Diffraction (SC XRD). Crystal and molecular structures of three salts: TFM_Na (CCDC: 2173257), TFM_Cs (CCDC: 2165288) and TFM_NH4 (CCDC: 2165281) were determined and deposited. Compared to the native TFM, for all crystalline salt structures, a conformational change of the teriflunomide molecule involving about 180-degree rotation of the end group, forming an intramolecular hydrogen bond N-H⋯O is observed. By applying a complementary multi-technique approach, employing 1D and 2D solid state MAS NMR techniques, single and powder X-ray diffraction measurements, as well as the DFT-based GIPAW calculations of NMR chemical shifts for TFM_Na and TFM_Cs allowed to propose structural features of TFM_Li for which it was not possible to obtain adequate material for single crystal X-Ray measurement.
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Affiliation(s)
- Tomasz Pawlak
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland.
| | - Piotr Paluch
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
| | - Rafał Dolot
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
| | - Grzegorz Bujacz
- Institute of Molecular and Industrial Biotechnology, Lodz University of Technology, Stefanowskiego 4/10, 90-924, Lodz, Poland
| | - Marek J Potrzebowski
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363, Lodz, Poland
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3
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Pokorný V, Touš P, Štejfa V, Růžička K, Rohlíček J, Czernek J, Brus J, Červinka C. Anisotropy, segmental dynamics and polymorphism of crystalline biogenic carboxylic acids. Phys Chem Chem Phys 2022; 24:25904-25917. [PMID: 36260017 DOI: 10.1039/d2cp03698c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Carboxylic acids of the Krebs cycle possess invaluable biochemical significance. Still, there are severe gaps in the availability of thermodynamic and crystallographic data, as well as ambiguities prevailing in the literature on the thermodynamic characterization and polymorph ranking. Providing an unambiguous description of the structure, thermodynamics and polymorphism of their neat crystalline phases requires a complex multidisciplinary approach. This work presents results of an extensive investigation of the structural anisotropy of the thermal expansion and local dynamics within these crystals, obtained from a beneficial cooperation of NMR crystallography and ab initio calculations of non-covalent interactions. The observed structural anisotropy and spin-lattice relaxation times are traced to large spatial variations in the strength of molecular interactions in the crystal lattice, especially in the orientation of the hydrogen bonds. A completely resolved crystal structure for oxaloacetic acid is reported for the first time. Thanks to multi-instrumental calorimetric effort, this work clarifies phase behavior, determines third-law entropies of the crystals, and states definitive polymorph ranking for succinic and fumaric acids. These thermodynamic observations are then interpreted in terms of first-principles quasi-harmonic calculations of cohesive properties. A sophisticated model capturing electronic, thermal, and configurational-entropic effects on the crystal structure approaches captures the subtle Gibbs energy differences governing polymorph ranking for succinic and fumaric acids, representing another success story of computational chemistry.
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Affiliation(s)
- Václav Pokorný
- Department of Physical Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic.
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, CZ-162 06 Prague 6, Czech Republic
| | - Petr Touš
- Department of Physical Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic.
| | - Vojtěch Štejfa
- Department of Physical Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic.
| | - Květoslav Růžička
- Department of Physical Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic.
| | - Jan Rohlíček
- Institute of Physics, Czech Academy of Sciences, Na Slovance 2, CZ-182 21 Prague 8, Czech Republic
| | - Jiří Czernek
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, CZ-162 06 Prague 6, Czech Republic
| | - Jiří Brus
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovského nám. 2, CZ-162 06 Prague 6, Czech Republic
| | - Ctirad Červinka
- Department of Physical Chemistry, University of Chemistry and Technology Prague, Technická 5, CZ-166 28 Prague 6, Czech Republic.
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4
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Al-Ani A, Szell PMJ, Rehman Z, Blade H, Wheatcroft HP, Hughes LP, Brown SP, Wilson CC. Combining X-ray and NMR Crystallography to Explore the Crystallographic Disorder in Salbutamol Oxalate. CRYSTAL GROWTH & DESIGN 2022; 22:4696-4707. [PMID: 35971412 PMCID: PMC9374327 DOI: 10.1021/acs.cgd.1c01093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 06/30/2022] [Indexed: 06/15/2023]
Abstract
Salbutamol is an active pharmaceutical ingredient commonly used to treat respiratory distress and is listed by the World Health Organization as an essential medicine. Here, we establish the crystal structure of its oxalate form, salbutamol oxalate, and explore the nature of its crystallographic disorder by combined X-ray crystallography and 13C cross-polarization (CP) magic-angle spinning (MAS) solid-state NMR. The *C-OH chiral center of salbutamol (note that the crystal structures are a racemic mixture of the two enantiomers of salbutamol) is disordered over two positions, and the tert-butyl group is rotating rapidly, as revealed by 13C solid-state NMR. The impact of crystallization conditions on the disorder was investigated, finding variations in the occupancy ratio of the *C-OH chiral center between single crystals and a consistency across samples in the bulk powder. Overall, this work highlights the contrast between investigating crystallographic disorder by X-ray diffraction and solid-state NMR experiment, and gauge-including projector-augmented-wave (GIPAW) density functional theory (DFT) calculations, with their combined use, yielding an improved understanding of the nature of the crystallographic disorder between the local (i.e., as viewed by NMR) and longer-range periodic (i.e., as viewed by diffraction) scale.
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Affiliation(s)
- Aneesa
J. Al-Ani
- Centre
for Sustainable and Circular Technologies (CSCT), University of Bath, Claverton Down, Bath BA2
7AY, U.K.
| | | | - Zainab Rehman
- Department
of Physics, University of Warwick, Coventry CV4 7AL, U.K.
| | - Helen Blade
- Oral
Product Development, Pharmaceutical Technology & Development,
Operations, AstraZeneca, Macclesfield SK10 2NA, U.K.
| | - Helen P. Wheatcroft
- Chemical
Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield SK10 2NA, U.K.
| | - Leslie P. Hughes
- Oral
Product Development, Pharmaceutical Technology & Development,
Operations, AstraZeneca, Macclesfield SK10 2NA, U.K.
| | - Steven P. Brown
- Department
of Physics, University of Warwick, Coventry CV4 7AL, U.K.
| | - Chick C. Wilson
- Centre
for Sustainable and Circular Technologies (CSCT), University of Bath, Claverton Down, Bath BA2
7AY, U.K.
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5
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Kolganov AA, Gabrienko A, Stepanov AG. DFT approach to predict 13C NMR chemical shifts of hydrocarbon species adsorbed on Zn-modified zeolite. Phys Chem Chem Phys 2022; 24:22241-22249. [DOI: 10.1039/d2cp02468c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
13C MAS NMR spectroscopy is a powerful technique to study the mechanisms of hydrocarbon transformations on heterogeneous catalysts. It can reliably identify the surface intermediates and the adsorbed products based...
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6
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Szell PMJ, Nilsson Lill SO, Blade H, Brown SP, Hughes LP. A toolbox for improving the workflow of NMR crystallography. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2021; 116:101761. [PMID: 34736104 DOI: 10.1016/j.ssnmr.2021.101761] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/04/2021] [Accepted: 10/04/2021] [Indexed: 06/13/2023]
Abstract
NMR crystallography is a powerful tool with applications in structural characterization and crystal structure verification, to name two. However, applying this tool presents several challenges, especially for industrial users, in terms of consistency, workflow, time consumption, and the requirement for a high level of understanding of experimental solid-state NMR and GIPAW-DFT calculations. Here, we have developed a series of fully parameterized scripts for use in Materials Studio and TopSpin, based on the .magres file format, with a focus on organic molecules (e.g. pharmaceuticals), improving efficiency, robustness, and workflow. We separate these tools into three major categories: performing the DFT calculations, extracting & visualizing the results, and crystallographic modelling. These scripts will rapidly submit fully parameterized CASTEP jobs, extract data from the calculations, assist in visualizing the results, and expedite the process of structural modelling. Accompanied with these tools is a description on their functionality, documentation on how to get started and use the scripts, and links to video tutorials for guiding new users. Through the use of these tools, we hope to facilitate NMR crystallography and to harmonize the process across users.
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Affiliation(s)
| | - Sten O Nilsson Lill
- Early Product Development and Manufacturing, Pharmaceutical Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Helen Blade
- Oral Product Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield, UK
| | - Steven P Brown
- Department of Physics, University of Warwick, Coventry, CV4 7AL, UK.
| | - Leslie P Hughes
- Oral Product Development, Pharmaceutical Technology & Development, Operations, AstraZeneca, Macclesfield, UK.
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7
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Duong NT, Aoyama Y, Kawamoto K, Yamazaki T, Nishiyama Y. Structure Solution of Nano-Crystalline Small Molecules Using MicroED and Solid-State NMR Dipolar-Based Experiments. Molecules 2021; 26:4652. [PMID: 34361806 PMCID: PMC8347922 DOI: 10.3390/molecules26154652] [Citation(s) in RCA: 6] [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: 07/01/2021] [Revised: 07/24/2021] [Accepted: 07/27/2021] [Indexed: 11/16/2022] Open
Abstract
Three-dimensional electron diffraction crystallography (microED) can solve structures of sub-micrometer crystals, which are too small for single crystal X-ray crystallography. However, R factors for the microED-based structures are generally high because of dynamic scattering. That means R factor may not be reliable provided that kinetic analysis is used. Consequently, there remains ambiguity to locate hydrogens and to assign nuclei with close atomic numbers, like carbon, nitrogen, and oxygen. Herein, we employed microED and ssNMR dipolar-based experiments together with spin dynamics numerical simulations. The NMR dipolar-based experiments were 1H-14N phase-modulated rotational-echo saturation-pulse double-resonance (PM-S-RESPDOR) and 1H-1H selective recoupling of proton (SERP) experiments. The former examined the dephasing effect of a specific 1H resonance under multiple 1H-14N dipolar couplings. The latter examined the selective polarization transfer between a 1H-1H pair. The structure was solved by microED and then validated by evaluating the agreement between experimental and calculated dipolar-based NMR results. As the measurements were performed on 1H and 14N, the method can be employed for natural abundance samples. Furthermore, the whole validation procedure was conducted at 293 K unlike widely used chemical shift calculation at 0 K using the GIPAW method. This combined method was demonstrated on monoclinic l-histidine.
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Affiliation(s)
- Nghia Tuan Duong
- RIKEN-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan;
| | | | | | - Toshio Yamazaki
- RIKEN Center for Biosystems Dynamics Research, RIKEN, Yokohama, Kanagawa 230-0045, Japan;
| | - Yusuke Nishiyama
- RIKEN-JEOL Collaboration Center, RIKEN, Yokohama, Kanagawa 230-0045, Japan;
- JEOL RESONANCE Inc., Akishima, Tokyo 196-8558, Japan
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8
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Scarperi A, Barcaro G, Pajzderska A, Martini F, Carignani E, Geppi M. Structural Refinement of Carbimazole by NMR Crystallography. Molecules 2021; 26:molecules26154577. [PMID: 34361730 PMCID: PMC8347463 DOI: 10.3390/molecules26154577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 11/16/2022] Open
Abstract
The characterization of the three-dimensional structure of solids is of major importance, especially in the pharmaceutical field. In the present work, NMR crystallography methods are applied with the aim to refine the crystal structure of carbimazole, an active pharmaceutical ingredient used for the treatment of hyperthyroidism and Grave’s disease. Starting from previously reported X-ray diffraction data, two refined structures were obtained by geometry optimization methods. Experimental 1H and 13C isotropic chemical shift measured by the suitable 1H and 13C high-resolution solid state NMR techniques were compared with DFT-GIPAW calculated values, allowing the quality of the obtained structure to be experimentally checked. The refined structure was further validated through the analysis of 1H-1H and 1H-13C 2D NMR correlation experiments. The final structure differs from that previously obtained from X-ray diffraction data mostly for the position of hydrogen atoms.
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Affiliation(s)
- Andrea Scarperi
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.S.); (F.M.)
| | - Giovanni Barcaro
- Institute For Chemical And Physical Processes, Italian National Council for Research, CNR/IPCF, Via G. Moruzzi 1, 56124 Pisa, Italy;
| | - Aleksandra Pajzderska
- Department of Radiospectroscopy, Faculty of Physics, Adam Mickiewicz University, Uniwersytetu Poznanskiego 2, 61-614 Poznan, Poland;
| | - Francesca Martini
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.S.); (F.M.)
- Center for Instrument Sharing, University of Pisa (CISUP), 56126 Pisa, Italy
| | - Elisa Carignani
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.S.); (F.M.)
- Institute for the Chemistry of OrganoMetallic Compounds, Italian National Council for Research, CNR/ICCOM, Via G. Moruzzi 1, 56124 Pisa, Italy
- Correspondence: (E.C.); (M.G.); Tel.: +39-050-2219353 (E.C.); +39-050-2219289 (M.G.)
| | - Marco Geppi
- Department of Chemistry and Industrial Chemistry, University of Pisa, Via G. Moruzzi 13, 56124 Pisa, Italy; (A.S.); (F.M.)
- Center for Instrument Sharing, University of Pisa (CISUP), 56126 Pisa, Italy
- Institute for the Chemistry of OrganoMetallic Compounds, Italian National Council for Research, CNR/ICCOM, Via G. Moruzzi 1, 56124 Pisa, Italy
- Correspondence: (E.C.); (M.G.); Tel.: +39-050-2219353 (E.C.); +39-050-2219289 (M.G.)
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9
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Analyzing Discrepancies in Chemical-Shift Predictions of Solid Pyridinium Fumarates. Molecules 2021; 26:molecules26133857. [PMID: 34202841 PMCID: PMC8270278 DOI: 10.3390/molecules26133857] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 06/21/2021] [Accepted: 06/21/2021] [Indexed: 01/29/2023] Open
Abstract
Highly accurate chemical-shift predictions in molecular solids are behind the success and rapid development of NMR crystallography. However, unusually large errors of predicted hydrogen and carbon chemical shifts are sometimes reported. An understanding of these deviations is crucial for the reliability of NMR crystallography. Here, recently reported large deviations of predicted hydrogen and carbon chemical shifts of a series of solid pyridinium fumarates are thoroughly analyzed. The influence of the geometry optimization protocol and of the computational level of NMR calculations on the accuracy of predicted chemical shifts is investigated. Periodic calculations with GGA, meta-GGA and hybrid functionals are employed. Furthermore, molecular corrections at the coupled-cluster singles-and-doubles (CCSD) level are calculated. The effect of nuclear delocalization on the structure and NMR shielding is also investigated. The geometry optimization with a computationally demanding hybrid functional leads to a substantial improvement in proton chemical-shift predictions.
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10
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Pawlak T, Sudgen I, Bujacz G, Iuga D, Brown SP, Potrzebowski MJ. Synergy of Solid-State NMR, Single-Crystal X-ray Diffraction, and Crystal Structure Prediction Methods: A Case Study of Teriflunomide (TFM). CRYSTAL GROWTH & DESIGN 2021; 21:3328-3343. [PMID: 34267599 PMCID: PMC8273857 DOI: 10.1021/acs.cgd.1c00123] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 04/27/2021] [Indexed: 06/13/2023]
Abstract
In this work, for the first time, we present the X-ray diffraction crystal structure and spectral properties of a new, room-temperature polymorph of teriflunomide (TFM), CSD code 1969989. As revealed by DSC, the low-temperature TFM polymorph recently reported by Gunnam et al. undergoes a reversible thermal transition at -40 °C. This reversible process is related to a change in Z' value, from 2 to 1, as observed by variable-temperature 1H-13C cross-polarization (CP) magic-angle spinning (MAS) solid-state NMR, while the crystallographic system is preserved (triclinic). Two-dimensional 13C-1H and 1H-1H double-quantum MAS NMR spectra are consistent with the new room-temperature structure, including comparison with GIPAW (gauge-including projector augmented waves) calculated NMR chemical shifts. A crystal structure prediction procedure found both experimental teriflunomide polymorphs in the energetic global minimum region. Differences between the polymorphs are seen for the torsional angle describing the orientation of the phenyl ring relative to the planarity of the TFM molecule. In the low-temperature structure, there are two torsion angles of 4.5 and 31.9° for the two Z' = 2 molecules, while in the room-temperature structure, there is disorder that is modeled with ∼50% occupancy between torsion angles of -7.8 and 28.6°. These observations are consistent with a broad energy minimum as revealed by DFT calculations. PISEMA solid-state NMR experiments show a reduction in the C-H dipolar coupling in comparison to the static limit for the aromatic CH moieties of 75% and 51% at 20 and 40 °C, respectively, that is indicative of ring flips at the higher temperature. Our study shows the power of combining experiments, namely DSC, X-ray diffraction, and MAS NMR, with DFT calculations and CSP to probe and understand the solid-state landscape, and in particular the role of dynamics, for pharmaceutical molecules.
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Affiliation(s)
- Tomasz Pawlak
- Centre
of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland
| | - Isaac Sudgen
- Molecular
Systems Engineering Group, Centre for Process Systems Engineering,
Department of Chemical Engineering, Imperial
College London, London SW7 2AZ, U.K.
| | - Grzegorz Bujacz
- Institute
of Molecular and Industrial Biotechnology, Lodz University of Technology, Stefanowskiego 4/10, 90-924, Lodz, Poland
| | - Dinu Iuga
- Department
of Physics, University of Warwick, Coventry CV4 7AL, U.K.
| | - Steven P. Brown
- Department
of Physics, University of Warwick, Coventry CV4 7AL, U.K.
| | - Marek J. Potrzebowski
- Centre
of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Lodz, Poland
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11
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Czernek J, Brus J. Parametrizing the Spatial Dependence of 1H NMR Chemical Shifts in π-Stacked Molecular Fragments. Int J Mol Sci 2020; 21:E7908. [PMID: 33114411 PMCID: PMC7662755 DOI: 10.3390/ijms21217908] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 10/20/2020] [Accepted: 10/22/2020] [Indexed: 12/22/2022] Open
Abstract
Most recently a renewed interest in several areas has arisen in factors governing the 1H NMR chemical shift (1H CS) of protons in aromatic systems. Therefore, it is important to describe how 1H CS values are affected by π-stacking intermolecular interactions. The parametrization of radial and angular dependences of the 1H CS is proposed, which is based on conventional gauge-independent atomic orbital (GIAO) calculations of explicit molecular fragments. Such a parametrization is exemplified for a benzene dimer with intermonomer vertical and horizontal distances which are in the range of values often found in crystals of organic compounds. Results obtained by the GIAO calculations combined with B3LYP and MP2 methods were compared, and revealed qualitatively the same trends in the 1H CS data. The parametrization was found to be quantitatively correct for the T-shaped benzene dimers, and its limitations were discussed. Parametrized 1H CS surfaces should become useful for providing additional restraints in the search of site-specific information through an analysis of structurally induced 1H CS changes.
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Affiliation(s)
- Jiří Czernek
- Institute of Macromolecular Chemistry, Czech Academy of Sciences, Heyrovsky Square #2, 16206 Prague, Czech Republic;
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12
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Grüne M, Luxenhofer R, Iuga D, Brown SP, Pöppler AC. 14N–1H HMQC solid-state NMR as a powerful tool to study amorphous formulations – an exemplary study of paclitaxel loaded polymer micelles. J Mater Chem B 2020; 8:6827-6836. [DOI: 10.1039/d0tb00614a] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
14N–1H HMQC experiments are powerful experiments to characterize amorphous drug–polymer formulations of paclitaxel yielding well-separated signals in the 14N dimension as well as information on the symmetry of 14N and 14N–1H interactions.
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Affiliation(s)
- Marvin Grüne
- Institute of Organic Chemistry
- University of Würzburg
- 97074 Würzburg
- Germany
| | - Robert Luxenhofer
- Lehrstuhl für Chemische Technologie der Materialsynthese
- University of Würzburg
- 97070 Würzburg
- Germany
| | - Dinu Iuga
- Department of Physics
- University of Warwick
- Coventry
- UK
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