Proton NMR spectroscopy and

Intimate information about the nature of the H bond has come from vibrational spectro.scopy (infrared and Raman), proton nmr spectroscopy, and diffraction techniques (X-ray and neutron). In vibrational spectroscopy the presence of a hydrogen bond A-H B is manifest by the following effects ... 

Molecular Motions and Dynamic Structures. Molecular motions are of quite general occurrence in the solid state for molecules of high symmetry (22,23). If the motion does not introduce disorder into the crystal lattice (as, for example, the in-plane reorientation of benzene which occurs by 60° jumps between equivalent sites) it is not detected by diffraction measurements which will find a seemingly static lattice. Such molecular motions may be detected by wide-line proton NMR spectroscopy and quantified by relaxation-time measurements which yield activation barriers for the reorientation process. In addition, in some cases, the molecular reorientation may be coupled with a chemical exchange process as, for example, in the case of many fluxional organometallic molecules. ... 

Proton and 13C NMR spectral data of 33 derivatives of 64 have been tabulated and assigned <1996MRC409>. Several 3-oxo derivatives of 64 have been studied by proton and 13C NMR spectroscopy as part of a comprehensive investigation of their structural and spectroscopic properties <2003BCJ2361>. The regioselectivity of the formation of the six-membered ring in derivatives of 67 from 1,3-diketones has been established by proton NMR spectroscopy and nuclear Overhauser effects <1997CHE535>. 

Proton NMR spectroscopy and dielectic constant measurements provide evidence about the motion of the water molecules in crystal structures, as reviewed by Davidson and Ripmeester (1984). At very low temperatures (<50 K) molecular motion is frozen in so that hydrate lattices become rigid. The hydrate proton NMR analysis suggests that the first-order contribution to motion is due to reorientation of water molecules in the structure the second-order contribution is due to translational diffusion at these low temperatures. 

Otter, A., Scott, P. G., and Kotovych, G. (1988). Type-I collagen a-lchain C-telopep-tide—Solution structure determined by 600 MHz proton NMR spectroscopy and implications for its role in collagen fibrillogenesis. Biochemistry 27, 3560-3567. 

Collman JP, Barnes CE, Swepston PN, Ibers JA (1984) Synthesis, proton NMR spectroscopy, and structural characterization of binuclear ruthenium porphyrins. J Am Chem Soc 106 3500-3510... 

The isomer ratios 4 5 were then determined by GC analysis and 60 MHz proton NMR spectroscopy, and agreed within two percent with the values obtained from GC analysis of the reaction mixture. 

The elimination of FlCl from the diester 331 with base afforded a mixture of the diesters 332 and 333, both as E-Z mixtures, together with 334. During the course of contact with the base, the composition of the product mixture was determined by proton NMR spectroscopy and GLC. For the 0L,p- and j5,y-unsaturated esters, plots of composition vs time cross, showing their interconvertibility. Formation of the product 332 is kinetically controlled, and both 333 and 334 are the thermodynamically controlled products. At final equilibrium, the mixture of unsaturated esters 332-333-334 had the composition 12 84 4 Similar prototropic changes had been observe earlier during the dehydrochlorination of diethyl (2-chloropentyl)phosphonate. ... 

Plavec J, Koole LH, Chattopadhyaya J (1992) Structural analysis of 2, 3 -dideoxyinosine, 2, 3 -dideoxyadsenosine, 2, 3 -dideoxyguanosine, and 2, 3 -dideoxycytidine by 500-MHz proton-NMR spectroscopy and ab initio molecular orbital calculations. J Biochem Biophys Methods 25 253—272... 

Plavee J, Fabre-Buet V, Uteza V, Grouiller A, Chattopadhyaya J (1993) Conformational studies on some Cl -hranehed p-D-nueleosides by proton-NMR spectroscopy and molecular meehanies calculations. J Biochem Biophys Methods 26 317... 

Hayward, J.S., Ellis, B., and Rand, B. Characterization of pyrolysis products of pitch materials by broad line proton NMR spectroscopy and thermogravimetry. 1988 26 71-78. 

An OT M aqueous solution of the monomer was sealed in glass ampoules, under vacuum, after the application of the freeze-thaw technique. The ampoules were kept at room temperature for 24 h before being irradiated for 48 h in a cobalt-60 source (dose rate 2300 rad min " ). Polymerization was completed as determined by proton NMR spectroscopy and the content of the ampoules after water removal was characterized for liquid crystalline properties. 

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