Molecular dynamics of solid benzothiadiazine derivatives (Thiazides). A study by NMR, DTA and DFT methods

Effect of Sugars on the Molecular Motion of Freeze-Dried Protein Formulations Reflected by NMR Relaxation Times

“…Neutron scattering can probe atomic motions on the timescale of nanoseconds or shorter in freeze-dried formulations (22,23,34). NMR can detect atomic motions on the timescale of MHz and kHz, which are reflected by spin-lattice relaxation times in the laboratory and rotating frames (T 1 and T 1ρ ), respectively (35)(36)(37).…”

Towards Understanding Drugs on the Molecular Level to Design Drugs of Desired Profiles

“…This transition was not revealed by the temperature dependencies of the 1 H second moment or 1 H spin-lattice relaxation time (NMR), which were able to detect only trans-gauche jumps of -NH 2 . Moreover, the phase transition clearly visible in NQR was only weakly indicated by the thermal dependence of heat capacity (DTA measurements) [171]. This phase transition was interpreted as a change in the structural ordering connected with the reorientation of the -NH 2 group in a specific temperature in solid state i.e.…”

“…Interesting results have been obtained for hydrochlorothiazide (HCTZ), a diuretic drug applied to beat high blood pressure and heart failure. Among the DTA, NMR, NQR and XRD methods [171,172] the most sensitive to its phase transitions was NQR [172]. The anomalies in the temperature dependence of the 35 Cl NQR frequency for HCTZ, the change in the linewidth (being a result of an increase in the spin-lattice relaxation time), small but notable changes in the slope and the jump in frequency observed at 253 K, not exceeding 0.05 MHz, together with the lack of hysteresis (which distinguishes the first-and secondorder transitions) indicated a second-order transition.…”

Structure-activity study of thiazides by magnetic resonance methods (NQR, NMR, EPR) and DFT calculations

“…Optimisation of the HCTZ geometry was necessary as the positions of hydrogen atoms calculated in [25] are charged with significant error, e.g. the intermolecular and intramolecular contributions to the second moment of 1 H-NMR calculated on the basis of these data were almost twice overestimated [20]. The X-ray geometry of HCTZ was also taken as the initial data for geometry optimisation of the other thiazides.…”

“…This paper is a continuation of the cycle of works [14][15][16][17][18][19][20] devoted to analysis of the effect of the intra and intermolecular interactions on the electronic structure of thiazides in solid phase by the resonance methods: nuclear quadrupole resonance-NQR, nuclear magnetic resonance-NMR, and electron paramagnetic resonance-EPR. In the earlier works analysis of the spectroscopic parameters such as quadrupole coupling constant (QCC), NQR, chemical shift (d), chemical shift anisotropy (CSA), asymmetry parameter (h), NMR and hyperfine coupling constant (A), EPR has been made, the possible structures and active sites have been proposed, the electronic effects (polarisation and delocalisation) estimated and the influence of irradiation on the electron density distribution in molecules established.…”