13C MAS NMR spectroscopy

According to chemical analysis (Table II) and CP 13c MAS MMR spectroscopy. it can be concluded that the three propylammonium cations are occluded as ion pairs with F in the channels of the structure of the TPA[si]-MFI, TRIPA [Si]-MFI and DIPA [Si]-MFI samples. In the case of the two latter samples, the organic cations are hydrated (Table II) it will be seen later that the water molecules contribute significantly to the formation enthalpy of both materials. Also, CP 13C MAS NMR spectroscopy shows for the DIPA Si -MFI sample a small amount of TRIPA+ beside the DIPA+ cations (molar TRIPA+/DIPA+... 

Carbon dioxide behaves as a weak fluoride ion acceptor towards naked fluoride ion sources such as tetramethylammonium fluoride, neopentyl(trimethyl)-ammonium fluoride and piperidinium fluoride (pip+F ) in the absence of a solvent and in CH2F2 and CF3CHFCF3 solvents for pip+F [25]. The C02F anion has been characterized in the solid state by 1H 13C MAS NMR spectroscopy and... 

Group 4. - 13C MAS-NMR spectroscopy was used to investigate the nature of the active species Cp TiCl3/P, where P — functionalised 20% cross-linked chloromethylated polystyrene.79 27A1 NMR spectra were used to probe amorphisation processes in Al-Ti-Si composites, e.g. Al30Ti7o xSix, where x = 10, 20 or 30.80... 

C MAS-NMR spectroscopy was used to quantify the different carbon species in synthetically produced nanodiamonds.430 A 13C study has been reported to study the modification of the electronic properties of SWCNT by alkali intercalation.431,432 13C MAS-NMR data were used to study the structure of 13C-enriched SWCNT, prepared by catalytic decomposition of CH4.433 H, 13C and 15N MAS-NMR spectra of amorphous carbon nitride (a-CNx) films were consistent with sp2 hybridised nitrogen atoms in an aromatic carbon... 

Another type of derivatized silica surface that has received considerable attention is Cis-derivatized silica gel that is, silica gel that has been silylated with reagents such as Cl(CH3)2Si(CH2)i7CH3 (45-51). This system was studied via 13C NMR (47) and 2H NMR spectroscopy (45) as a function of surface loading of the Cis chains and of certain added liquids. The ability of cross polarization to select static components of a surface derivative relative to more mobile components—which would be emphasized by non-CP (single-pulse) techniques that rely on direct 13C spin-lattice relaxation—can be seen in Figure 8, which provides a comparison between the single-pulse and cross-polarization 13C MAS NMR spectroscopy results on four Cis-silica samples. Dramatic differences in line shapes and intensities, which can be interpreted at least qualitatively in terms of... 

Although limited by sensitivity, chemical reaction monitoring via less sensitive nuclei (such as 13C) has also been reported. In 1987 Albert et al. monitored the electrochemical reaction of 2,4,6-tri-t-butylphenol by continuous flow 13C NMR [4]. More recently, Hunger and Horvath studied the conversion of vapor propan-2-ol (13C labeled) on zeolites using 1H and 13C in situ magic angle spinning (MAS) NMR spectroscopy under continuous-flow conditions [15]. 

Golchin, A., Oades, J. M., Skjemstad, J. O., and Clarke, P. (1994b). Study of free and occluded particulate organic matter in soils by solid-state 13C CP/MAS NMR spectroscopy and scanning electron microscopy. Aust. J. Soil Res. 32(2), 285-309. 

Fukui, K., K. Sato, D. Shiomi, T. Takui, K. Itoh, K. Gotoh, T. Kubo, K. Yamamoto, K. Nakasuji, and A. Naito. 1999. Electronic structure of a stable phenalenyl radical in crystalline state as studied by SQUID measurements, cw-ESR, and 13C CP/MAS NMR spectroscopy. Synth. Metals 103 2257-2258. 

Desmotropy phenomenon (two tautomers crystallize in two different crystals) has been found for 3-methyl-4-nitropyrazole and its tautomer, 5-methyl-4-nitropyrazole by X-ray and 13C CP/MAS NMR spectroscopy [16]. 

Ammonium 3,5-dinitroindazolates have been studied in the solid state by 13C and 15N CP/MAS NMR spectroscopy [656],... 

The nature of the organic moieties grafted on Y zeolite supports having different Si/Al ratio and on silica was studied by 13c MAS-NMR and infrared spectroscopy. 

Characterisation of ZnAl204 powders was accomplished using 27A1 MAS-NMR spectroscopy.259 13C and 31P MAS-NMR spectra were used to study Zn(03PPh)(phen), Zn(03PR)2(phen) (R = Me, Et, Bz) and... 

Two-dimensional DQ H MAS-NMR spectra were used to investigate the local structure of a surfactant-templated silicate thin film.498 Silicalite-1 powders (20-1000 nm. crystals) were characterised by 29Si MAS-NMR spectroscopy.499 13C and 29Si solid-state NMR data were used to characterise organic-inorganic mesoporous silica-based materials.500... 

A phyllosilicate-rich clay was studied by 29Si MAS-NMR spectroscopy.520 13C CP/MAS-NMR and 29Si MAS-NMR spectra were used to characterise silylated montmorillonites, and to estimate the extent of the silylation reaction.521 Ab initio calculations have been made of 29Si NMR chemical shifts for silicate complexes with carboxylates, amino acids and multicarboxylic acids.522 Structural changes on thermal treatment of kaolinite were followed using 29Si MAS-NMR spectra.523... 

Variable-temperature Si H CP/MAS-NMR spectroscopy was used to study the effect of molecular oxygen on the location of sorbate molecules in highly-siliceous zeolite framework, e.g. ZSM-5 with adsorbed />-dibromoben-zene.662 13C MAS-NMR spectra were used to follow the conversion of methanol on weakly-dealuminated zeolite H-ZSM-5 - showing the formation of cyclic compounds and carbonium ions.663 There is 13C CP/MAS-NMR evidence for surface ra-alkoxyl groups formed by the modification of the proton-ated perovskite HCa2Nb3Oi0 by w-alcohols.664 13C CP/MAS-NMR spectra... 

C NMR spin-lattice relaxations in solid PMMAs of different tacticity were studied by CP/MAS NMR spectroscopy.324-328 The relaxation proceeds more slowly in isotactic PMMA than in syndiotactic PMMA even in the solid state this is because of the faster reorientation of the a-CH3 group in the isotactic chain.135 The nC-T times of the a-methyl carbons of PMMAs with different tacticities were measured over a wide range of temperatures by cross polarization, magic-angle spinning, dipole dephasing (CP/DD)... 

MT Zell, BE Padden, DJW Grant, MC Chapeau, I Prakash, EJ Munson. Two-dimensional high-speed CP/MAS NMR spectroscopy of polymorphs. 1. Uniformly 13C-labeled aspartame. J Am Chem Soc 121 1372-1378, 1999. 

Veregin, R.P., Fyfe, C.A. and Marchessault, R.H. (1987) Investigation of the crystalline V amylose complexes by high-resolution 13C CP/MAS NMR Spectroscopy. Macromolecules, 20,3(X)7-3012. Gidley, M.J. and Bociek, S.M. (1988) 13C CP/MAS NMR Studies of amylose inclusion complexes, cyclodextrins, and the amorphous phase of starch granules Relationships between glycosidic linkage conformation and solid-state 13C chemictil shifts. Journal of American Chemical Society, 110, 3820-3829. 

Duarte ML, Ferreira MC, Marvao MR et al (2001) Determination of the degree of acetylation of chitin materials by 13C CP/MAS NMR spectroscopy and solid state 13C NMR spectroscopy. Int J Biol Macnnnol 28 359-363... 

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