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od 2020-09-20

Title: Molecular dynamics of solid cortisol studied by NMR

Source: Molecular Physics

Year : 1996

Abstract:

Polycrystalline cortisol (hydrocortisone; 11 beta,17 alpha,21-trihydroxy-4-pregnene-3,20-dione; C21H30O5) has been investigated by continuous and pulse proton NMR methods between 78 and 400 K at Larmor frequencies of 7, 25 and 60 MHz. A reduced value of second moment was found above 90 K and is ascribed to reorientation of two methyl groups. A single asymmetric minimum was found in the temperature dependence of the spin-lattice relaxation times and this also is attributed to reorientation of two methyl groups. The asymmetry suggests an asymmetric distribution of correlation times of the motion. Using the Cole-Davidson distribution, the best computer fit yields the following parameters characterizing the motion: E(s) = 11.8 ±0.1 kJ mol(-1), tau(0) = 4.6 ±0.4) x 10(-13) s, distribution parameter delta = 0.62.

DOI: 10.1080/00268979650026154   (Pobrane:  aktualizowanie)