Here, we present a series of exclusively heteronuclear multidimensional NMR experiments, based on 13C direct detection, which exploit the (1)H polarization as a starting source to increase the signal-to-noise ratio. This contributes to make this spectroscopy more useful and usable. Examples are reported for a suitable system such as securin, an intrinsically disordered protein of 22 kDa.
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http://dx.doi.org/10.1016/j.jmr.2009.02.012 | DOI Listing |
RSC Adv
November 2024
Departamento de Química Inorgánica, Facultad de Ciencias Químicas, UCM E-28040 Madrid Spain.
The present study reports some fascinating results of Hantzsch's [3 + 2] cyclic condensation of α-bromo-1,3-diketones, a tri-electrophilic synthon generated by bromination of 1,3-diketones using the mild brominating reagent NBS with trinucleophilic -substituted thioureas. Interestingly, out of a total of 20 combinations, 10 resulted in the exclusive formation of the desired 2-(-arylamino)-5-acyl-4-methylthiazoles regioselectively, seven led to the formation of unexpected 2-(-acylimino)-3--aryl-4-methylthiazoles through an interesting C-N acyl migration, and three furnished a mixture consisting of both products. The regioselectivity pattern of the two products may be attributed to a greater electrophilicity of the carbonyl carbon of the acetyl group than that of the acyl group towards both nitrogens of thiourea.
View Article and Find Full Text PDFAnal Chem
September 2023
Environmental NMR Center, Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada.
Nuclear magnetic resonance (NMR) is a powerful technique with applications ranging from small molecule structure elucidation to metabolomics studies of living organisms. Typically, solution-state NMR requires a homogeneous liquid, and the whole sample is analyzed as a single entity. While adequate for homogeneous samples, such an approach is limited if the composition varies as would be the case in samples that are naturally heterogeneous or layered.
View Article and Find Full Text PDFInorg Chem
October 2023
Faculty of Chemistry, Warsaw University of Technology, 00-664 Warsaw, Poland.
Among numerous catalysts in the ring-opening copolymerization of epoxides with carbon dioxide (CO), zinc dicarboxylate complexes are the most common type, and in the family of metal-based homogeneous catalysts, zinc and magnesium complexes have attracted widespread attention. We report on the synthesis and structural characterization of a zinc-magnesium benzoate framework templated by the central hydroxide anion with μ-κ:κ:κ coordination mode, [ZnMg(μ-OH)(OCPh)] ( = 1 or 2). The resulting heterometallic system forms stable Lewis acid-base adducts with tetrahydrofuran (THF) and cyclohexene oxide (CHO), which crystallize as the hexanuclear zinc-magnesium hydroxide carboxylate cluster [ZnMg(μ-OH)(OCPh)(L)] (L = THF or CHO).
View Article and Find Full Text PDFJ Am Chem Soc
August 2023
State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.
Controlling the secondary phase in chiral liquid-crystalline (LC) polymers is of great importance since it transfers and amplifies molecular information to the macroscopic properties. However, the chiral superstructures of the LC phase are determined exclusively by the inherent configuration of the parent chiral source. Here, we report the switchable supramolecular chirality of heteronuclear structures by the untraditional command between common chiral "sergeant" units and various achiral "soldier" units.
View Article and Find Full Text PDFChemistry
March 2023
Institute of Chemistry, University of Rostock, Albert-Einstein-Str. 27, 18059, Rostock, Germany.
Sensitivity and specificity are both crucial for the efficient solid-state NMR structure determination of large biomolecules. We present an approach that features both advantages by site-specific enhancement of NMR spectroscopic signals from the protein-RNA binding site within a ribonucleoprotein (RNP) by dynamic nuclear polarization (DNP). This approach uses modern biochemical techniques for sparse isotope labeling and exploits the molecular dynamics of C-labeled methyl groups exclusively present in the protein.
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