Chain nuclear magnetic resonance

In addition to the major role it has played in the determination of the chemical structure of polymer chains, nuclear magnetic resonance (NMR) spectroscopy has provided information concerning microphase morphology and interfacial characteristics in both crystalline and non-crystalline systems. The investigation of microphases by this approach is possible because the molecular motion of segments is very dependent on their location in the structure. 

Because this problem is complex several avenues of attack have been devised in the last fifteen years. A combination of experimental developments (protein engineering, advances in x-ray and nuclear magnetic resonance (NMR), various time-resolved spectroscopies, single molecule manipulation methods) and theoretical approaches (use of statistical mechanics, different computational strategies, use of simple models) [5, 6 and 7] has led to a greater understanding of how polypeptide chains reach the native confonnation. 

Proton chemical shift data from nuclear magnetic resonance has historically not been very informative because the methylene groups in the hydrocarbon chain are not easily differentiated. However, this can be turned to advantage if a polar group is present on the side chain causing the shift of adjacent hydrogens downfteld. High resolution C-nmr has been able to determine position and stereochemistry of double bonds in the fatty acid chain (62). Broad band nmr has also been shown useful for determination of soHd fat content. 

The side-chain chlorine contents of benzyl chloride, benzal chloride, and benzotrichlorides are determined by hydrolysis with methanolic sodium hydroxide followed by titration with silver nitrate. Total chlorine determination, including ring chlorine, is made by standard combustion methods (55). Several procedures for the gas chromatographic analysis of chlorotoluene mixtures have been described (56,57). Proton and nuclear magnetic resonance shifts, characteristic iafrared absorption bands, and principal mass spectral peaks have been summarized including sources of reference spectra (58). Procedures for measuring trace benzyl chloride ia air (59) and ia water (60) have been described. 

Sharkey, W. H. Polymerizations Through the Carbon-Sulphur Double Bond. VoL 17, pp. 73-103. Shimidzu, T. Cooperative Actions in the Nucleophile-Containing Polymers. Vol. 23, pp. 55-102. Slichter, W. P. The Study of High Polymers by Nuclear Magnetic Resonance. VoL 1, pp. 35-74. Small, P. A. Long-Chain Branching in Polymers. VoL 18,pp. 1-64. 

Slichter, W. P. The Study of High Polymers by Nuclear Magnetic Resonance. Vol. 1, pp. 35-74. Small, P. A. Long-Chain Branching in Polymers. Vol. 18. 

Single-pulse proton nuclear magnetic resonance (NMR) spectroscopy has been used to demonstrate that the mean chain length of synovial fluid triglycerides is shorter than that in corresponding sera (Naughton etal.,... 

The presence of four kinds of nuclear magnetic resonance (NMR) observable nuclei ( H, uB, 13C, and 29Si) allows poly(m-carborane-siloxane) to be readily investigated using NMR spectroscopy. In addition, H spin-echo NMR relaxation techniques can provide an insight into polymer segmental chain dynamics and therefore useful information on material viscoelastic characteristics. 

Comonomers, such as 3-hydroxyvalerate (3HV, ethylene R-unit (-CH2-CH3) in Fig. 1) and 4-hydroxybutyrate, have been incorporated in the PHB chains using specific additives in the growth medium of the bacteria [21-25]. It has been shown by nuclear magnetic resonance (NMR) studies that poly(3HB-co-3HV) has a statistically random distribution of the monomer units throughout a range of compositions varying from 0 to 90 mol % 3HV [23-26]. 

Naphthalene-2,3-dicarboxaldehyde Nicotinamide adenine dinucleotide N-Acetylneuraminic acid 4-Fluoro-7-nitrobenzoxadiazole Naphthalene-2,3-dicarboxaldehyde Nondestructive readout Near infrared Near infrared fluorescence Nuclear magnetic resonance 2-Nitrophenyl oxalate 1,1 -Oxalyldiimidazole Polycyclic aromatic hydrocarbon Principal component analysis Photosensitized chemiluminescence Pentachlorophenyl oxalate Polymerase chain reaction... 

A solution structure of French Bean plastocyanin has been reported by Wright and co-workers,19 using nuclear magnetic resonance techniques described in Section 3.5 of Chapter 3. The structure, determined from a plastocyanin molecule in solution rather than in a solid-state crystal, agrees well with that of reduced poplar plastocyanin X-ray crystallographic structure reported above. Conformations of protein side chains constituting the hydrophobic core of the French bean plastocyanin are well-defined by the NMR technique. Surface side chains show... 

Nuclear magnetic resonance (NMR) is a very popular technique in the field of polymer analysis [1-3]. It can be used to measure Mn, but this application relies heavily on the presence of NMR signals due to terminal groups (TEG). As the length of the chains grows, the NMR signal due to TEG becomes weak and the accuracy falls. In practice, above 30 kDa the error level on Mn is so high that the measurement is useless. 

---