scholarly journals Insight into the chromophore of rhodopsin and its Meta-II photointermediate by 19F solid-state NMR and chemical shift tensor calculations

2018 ◽  
Vol 20 (48) ◽  
pp. 30174-30188 ◽  
Author(s):  
Andreas Brinkmann ◽  
Ulrich Sternberg ◽  
Petra H. M. Bovee-Geurts ◽  
Isabelle Fernández Fernández ◽  
Johan Lugtenburg ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Active State ◽  
Chemical Shift Tensor ◽  
Nmr Studies ◽  
Polarization Theory ◽  
Bond Polarization ◽  
Insight Into

19F solid-state NMR studies together with bond polarization theory chemical shift tensor calculations provide insight into the chromophore of rhodopsin and its active state Meta II.

A 13C solid-state NMR investigation of four cocrystals of caffeine and theophylline

2017 ◽  
Vol 73 (3) ◽  
pp. 234-243 ◽  
Author(s):  
Nicolas J. Vigilante ◽  
Manish A. Mehta
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Chemical Shifts ◽  
Active Pharmaceutical Ingredient ◽  
Magic Angle Spinning ◽  
Chemical Shift Tensor ◽  
Magic Angle ◽  
Isotropic Chemical Shifts ◽  
Angle Spinning

We report an analysis of the 13C solid-state NMR chemical shift data in a series of four cocrystals involving two active pharmaceutical ingredient (API) mimics (caffeine and theophylline) and two diacid coformers (malonic acid and glutaric acid). Within this controlled set, we make comparisons of the isotropic chemical shifts and the principal values of the chemical shift tensor. The dispersion at 14.1 T (600 MHz 1H) shows crystallographic splittings in some of the resonances in the magic angle spinning spectra. By comparing the isotropic chemical shifts of individual C atoms across the four cocrystals, we are able to identify pronounced effects on the local electronic structure at some sites. We perform a similar analysis of the principal values of the chemical shift tensors for the anisotropic C atoms (most of the ring C atoms for the API mimics and the carbonyl C atoms of the diacid coformers) and link them to differences in the known crystal structures. We discuss the future prospects for extending this type of study to incorporate the full chemical shift tensor, including its orientation in the crystal frame of reference.

Fluorination of supramolecular liquid crystals – tuning tool and analytical probe

2017 ◽  
Vol 5 (9) ◽  
pp. 2235-2239 ◽  
Author(s):  
Matthias Spengler ◽  
Ronald Y. Dong ◽  
Carl A. Michal ◽  
Michael Pfletscher ◽  
Michael Giese
Keyword(s):  
Liquid Crystals ◽  
Solid State ◽  
Solid State Nmr ◽  
Molecular Alignment ◽  
Nmr Studies ◽  
The Impact ◽  
Insight Into ◽  
Hydrogen Bonded

The impact of fluorination on the properties of photo-responsive hydrogen-bonded liquid crystals is reported and19F solid-state NMR studies provide insight into the molecular alignment of the assemblies.

scholarly journals Linear dicoordinate beryllium: a 9Be solid-state NMR study of a discrete zero-valent s-block beryllium complex

2018 ◽  
Vol 96 (7) ◽  
pp. 646-652 ◽  
Author(s):  
C. Leroy ◽  
J.K. Schuster ◽  
T. Schaefer ◽  
K. Müller-Buschbaum ◽  
H. Braunschweig ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Chemical Shift Tensor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Quadrupolar Coupling ◽  
Nmr Study ◽  
Tensor Data

Beryllium-9 (9Be) quadrupolar coupling and chemical shift tensor data are reported for bis(1-(2,6-diisopropylphenyl)-3,3,5,5-tetramethylpyrrolidine-2-ylidene)beryllium (Be(CAAC)2). These are the first such data for beryllium in a linear dicoordinate environment. The 9Be quadrupolar coupling constant, 2.36(0.02) MHz, is the largest recorded in the solid state to date for this isotope. The span of the beryllium chemical shift tensor, 22(2) ppm, covers about half of the known 9Be chemical shift range, and the isotropic 9Be chemical shift, 32.0(0.3) ppm, is the largest reported in the solid state to our knowledge. DFT calculations reproduce the experimental data well. A natural localized molecular orbital approach has been used to explain the origins and orientation of the beryllium electric field gradient tensor. The single-crystal X-ray structure of a second polymorph of Be(CAAC)2 is also reported. Inspection of the powder X-ray diffraction data shows that the new crystal structure is part of the bulk product next to another crystalline phase. Therefore, experimental X-ray powder data for the microcrystalline powder sample and the SSNMR data do not fully match either the originally reported crystal structure (Arrowsmith et al. Nat. Chem. 2016, 8, 890–894) or the new polymorph. The ability of solid-state NMR and powder X-ray diffraction to characterize powdered samples was thus particularly useful in this work.

scholarly journals Solid-State NMR Studies of the Succinate-Acetate Permease from Citrobacter Koseri in Liposomes and Native Nanodiscs

Life ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 908
Author(s):  
Xing-Qi Dong ◽  
Jing-Yu Lin ◽  
Peng-Fei Wang ◽  
Yi Li ◽  
Jian Wang ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Solid State Nmr ◽  
Protein Structures ◽  
Anion Channel ◽  
Transmembrane Domains ◽  
Helical Structures ◽  
Nmr Studies ◽  
Two Samples ◽  
Lipid Environment

The succinate-acetate permease (SatP) is an anion channel with six transmembrane domains. It forms different oligomers, especially hexamers in the detergent as well as in the membrane. Solid-state NMR studies of SatP were carried out successfully on SatP complexes by reconstructing the protein into liposomes or retaining the protein in the native membrane of E. Coli., where it was expressed. The comparison of 13C-13C 2D correlation spectra between the two samples showed great similarity, opening the possibility to further study the acetate transport mechanism of SatP in its native membrane environment. Solid-state NMR studies also revealed small chemical shift differences of SatP in the two different membrane systems, indicating the importance of the lipid environment in determining the membrane protein structures and dynamics. Combining different 2D SSNMR spectra, chemical shift assignments were made on some sites, consistent with the helical structures in the transmembrane domains. In the end, we pointed out the limitation in the sensitivity for membrane proteins with such a size, and also indicated possible ways to overcome it.

scholarly journals Insight into the local environment of magnesium and calcium in low-coordination-number organo-complexes using 25Mg and 43Ca solid-state NMR: a DFT study

2017 ◽  
Vol 73 (3) ◽  
pp. 208-218 ◽  
Author(s):  
Christel Gervais ◽  
Cameron Jones ◽  
Christian Bonhomme ◽  
Danielle Laurencin
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Metal Ions ◽  
Solid State Nmr ◽  
Chemical Shift Anisotropy ◽  
Local Environment ◽  
Coordination Numbers ◽  
Highly Sensitive ◽  
Calcium Complexes ◽  
Insight Into

With the increasing number of organocalcium and organomagnesium complexes under development, there is a real need to be able to characterize in detail their local environment in order to fully rationalize their reactivity. For crystalline structures, in cases when diffraction techniques are insufficient, additional local spectroscopies like 25Mg and 43Ca solid-state NMR may provide valuable information to help fully establish the local environment of the metal ions. In this current work, a prospective DFT investigation on crystalline magnesium and calcium complexes involving low-coordination numbers and N-bearing organic ligands was carried out, in which the 25Mg and 43Ca NMR parameters [isotropic chemical shift, chemical shift anisotropy (CSA) and quadrupolar parameters] were calculated for each structure. The analysis of the calculated parameters in relation to the local environment of the metal ions revealed that they are highly sensitive to very small changes in geometry/distances, and hence that they could be used to assist in the refinement of crystal structures. Moreover, such calculations provide a guideline as to how the NMR measurements will need to be performed, revealing that these will be very challenging.

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