Nmr chemical shifts

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  • It is difficult to overemphasize the importance of magnetic resonance techniques in chemistry. Experimental spectra can usually be successfully interpreted empirically, but more difficult cases require a prediction based on the electronic structure. In the last 25 years the calculation of magnetic resonance parameters from first principles has become a powerful research tool that can significantly enhance the utility of magnetic resonance techniques when empirical interpretations are insufficient.

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  • Since the subject of nuclear magnetic resonance (NMR) was awarded its first Nobel Prize in 1952 due to its successful detection by Bloch and Purcell in 1945, the technology and its applications have developed tremendously. The first two decades were focused on technical developments of instrumentation and methodologies to apply to the structure determination of compounds. During the late 1970s, several research groups developed modifications of NMR probes to convert them to an online mode for the analysis of sample mixtures....

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  • The 1 H- and 13 C-spectra of some azomethines of 5-amino-2-phenylindole series have been recorded and researched. It shown that, the substituents in benzene ring influenced on the chemical shift of proton on azomethine bond.

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  • We have used the NMR ACD/I-LABs simulation program to predict the 1 H and 13 C chemical shift of some suggested structures of the sample. The correct structure was determined by combining the MS and NMR simulation spectra with the experimental ones.

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  • Lecture Organic chemistry - Chapter 10: Nuclear magnetic resonance (NMR) spectroscopy. In this chapter, the following content will be discussed: What is spectroscopy? General spectrometer, the chemical shift δ, complex splitting patterns,...and other contents.

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  • The NMR solution structures of NTX-1 (PDB code 1W6B and BMRB 6288), a long neurotoxin isolated from the venom ofNaja naja oxiana, and the molecular dynamics simulation of these structures are reported. Calculations are based on 1114NOEs, 19 hydrogen bonds, 19 dihedral angle restraints and secondary chemical shifts derived from 1 Hto 13 C HSQC spectrum. Similar to other long neurotoxins, the three-finger like structure shows a double and a triple strandedb-sheet aswell as some flexible regions, particularly at the tip of loop II and the C-terminal tail....

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  • Some 5-nitrophenylfurane-2-aldehydes, 5-nitrophenylthiophen-2-aldehydes and two phenylhidrazones were synthesized. The 1 H-nMR, 13C-NMR and 2D-NMR spectra were assignted in DMSO by 500 MHz–NMR spectrometer. The spectra showed the influence of NO2–group to the chemical shift of 1 H- and 13C of the molecules.

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  • Guanosine triphosphate nucleotide analogues such as GppNHp (also named GMPPNP) or GTPcS are widely used to stabilize rapidly hydrolyzing protein-nucleotide complexes and to investigate biochemical reaction pathways. Here we describe the chemical synthesis of guanosine 5¢-O-(c-amidotriphosphate) (GTPcNH2) and a new synthesis of guanosine 5¢-O-(c-fluorotriphosphate) (GTPcF). The two nucleotides were characterized using NMR spectroscopy and isothermal titration calorimetry. Chemical shift data on 31P, 19F and 1H NMR resonances are tabulated.

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  • Chapter 13 - Nuclear magnetic resonance spectroscopy. In this chapter, students will be able to understand: Use the chemical shifts, splitting patterns, and integrations shown in a proton NMR spectrum to propose structures for possible compounds; use the number of peaks and their chemical shifts in a 13C NMR spectrum to determine the number of types of carbon atoms in the compound and what functional groups they might represent;...

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