Deuterium NMR and x-ray crystallographic studies of guest and host motions in the thiourea/1,4-di-tert-butylbenzene inclusion compound

Abstract

5121 (23) Clegg, H. P.; Rowlinson, J. S. Faraday SOC. Tram. 1955,51,1333. (24) Gugnoni, R. J.; Eldrige, J. w.; Okay, V. C.; Lee, T. J. AIChE J. 1974, (25) Aftienjew, J.; Zawisza, A. J. Chem. Thermodyn. 1977, 9, 153. (26) Haselden, G. G.; Newitt, D. M.; Shah, S. M. Proc. R. SOC. A 1951, (19) Prausnitz, J. M.; Lichtenthaler, R. N.; Gomes de Azevedo, E.Deuterium nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation times are used to investigate the guest and host molecular dynamics of solid 1 ,4-di-terr-butylbenzene-d4 (DTBB-d4), l,4-di-tert-butylbenzne-dl* (DTBB-d18), the thiourea/ 1 ,4-di-tert-butylbenzene-d4 inclusion compound (TUIDTBB-d4), the thiourea/ 1,4-di-tert-butylbenzene-d~ inclusion compound (TU/DTBB-dz2), the thiourea-d4/ 1,4-di-tert-butylbenzene inclusion compound (TU-d4/DTBB), and thiourea-d4 (TU-d4). X-ray crystallographic studies of TU/DTBB-d4 have been carried out at 291 K. In solid DTBB the phenyl ring is essentially static whereas the rert-butyl groups are undergoing rapid reorientation of both methyl and rert-butyl groups.Attempts to analyze the ' H spectra and Tl data for DTBB-dls suggest that the dynamics of the methyl and tert-butyl groups are nearly equivalent, and as a result, a satisfactory analysis, yielding methyl and tert-butyl rotational activation energies, was not possible. X-ray diffraction results for TU/DTBB-d4 suggest that, at 291 K, the phenyl ring is occupying three nearly equivalent sites. The ZH NMR line shapes between 186 and 392 K were interpreted using a model in which the phenyl ring is rapidly flipping between three positions, with one position less favored. At 296 and 186 K the populations are 0.81:1.00.1.00 and 0.201.00.1 .OO, respectively. Relaxation times obtained between 1 1 1 and 322 K show no mini", supporting the assumption of very rapid phenyl ring reorientation. For TU/DTBB-d2z a high-temperature T1 minimum is well-defined, and a second minimum, corresponding to tert-butyl group rotation, is reached at the lowest attainable temperatures. Lineshape simulations of the spectrum at 77 K yield methyl and tert-butyl group rotational rates of 1.0 X lo3 and 2.0 X 106 s-l, respectively. Analysis of the higher temperature spectra (109-172 K) and T1 data (167-300 K) yield methyl rotation activation energies of 12.7 and 12.3 kJ/mol, respectively. Deuterium line-shape studies of the thiourea dynamics in TU-d4 and TU-d4/DTBB yield activation energies for 180' flips about the C-S bond of 47 and 46 kJ/mol, respectively.Starting from the PY-like integral equation of RISM-1 type and using the Kirkwood-Buff theory, we evaluated the differences in the partial molar volumes of solute V : of cis and trans isomers. The system investigated consists of a tetratomic A-B-B-A fused hard sphere and a single hard sphere both of which are considered as solvent or solute. To compare the evaluated values with the actual values, the VTs were determined for cis-and trans-decahydronaphthalene dissolved in such solvents as carbon tetrachloride, hexane, and benzene, etc., as well as ...

A deuterium NMR study of molecular dynamics and geometry in two classes of onium salts: (CH3)3E+X− and C6H5M(CH3)3+I−

“…Previous work by Ripmeester and Ratcliffe (8,9) demonstrated that, in trimethyl and tetramethylammonium salts, both CS and C, rotation may be in the intermediate exchange region at low temperatures. It was also shown that in some (CH,),CX systems Cj rotation is rapid at low temperatures, whereas C3 rotation is slow (7,12). In principle it should be possible to reproduce the spectra shown in Fig.…”

“…It is often relatively easy to introduce ' H into a variety of molecular systems (4), and ' H N M R techniques can be used to study molecular dynamics with exchange rates, k, ranging from lo-' to lo9 s-' (1). The molecular motions of numerous solid trimethyl systems of the type (CH,),M, where M is CSH (3,CBr ( 6 ) , CC1, C1, CCHO (7), NH+, NCH,+ (8,9), S=O+ (lo), N (1 I), and CC,H, (12), have been studied by deuterium N M R spectroscopy.…”

Grinding-Induced Equimolar Complex Formation between Thiourea and Ethenzamide

“…1) Most of the thiourea inclusion complexes showed incommensurate structural properties. 7,8) Temperature-dependent phase transition of a thiourea inclusion complex from conventional rhombohedral tunnel structure to the monoclinic form at low temperature was also reported. 9) Complexation property of thiourea has been applied for extraction and stabilization of foods and medicinal drugs.…”

Methyl and t‐Butyl Group Reorientation in Planar Aromatic Solids: Low‐Frequency Nuclear Magnetic Resonance Relaxometry and X‐Ray Diffraction

“…A class of molecules that has been rewarding to study are single-and fused-ring aromatic structures containing one or two t-butyl groups. [1][2][3][4][5][6][7][8] We have synthesized the organic molecule 3-t-butylchrysene, determined the molecular ͑Fig. 1͒ and crystal ͑Figs.…”

“…Finally, deuteron NMR spectroscopy, deuteron NMR relaxation rate studies, and x-ray diffraction have teamed up to better model the relationship between the complicated motions and aromatic ring distortions in 9-t-butylanthracene 27 as well as the dynamical behavior of t-butyl reorientation in 1,4-di-t-butylbenzene in inclusion compounds. 2 The main purposes of this paper are ͑1͒ to present the synthesis, the x-ray diffraction, and the temperature and frequency dependence of the proton spin-lattice relaxation rate in solid 3-t-butylchrysene, ͑2͒ to review the current dynamical model for t-butyl and methyl group motion and recast it in a more general way, and ͑3͒ to compare proton NMR relaxometry and x-ray diffraction studies of three other molecular solids with the results in 3-t-butylchrysene presented here. The three other systems are 4-methyl-2,6-di-tbutylphenol, 1,4-di-t-butylbenzene, and polymorph A of 2,6-di-t-butylnaphthalene.…”