Glass transition dynamics of anti-inflammatory ketoprofen studied by Raman scattering and terahertz time-domain spectroscopy

Abstract

A liquid-glass transition and a crystalline state of pharmaceutical racemic ketoprofen were studied by Raman scattering and the broadband terahertz time-domain spectroscopy (THz-TDS) in the frequency range from 9 to 260 cm-1. The low-frequency Raman scattering spectra clearly shows the remarkable change related to a liquid-glass transition at about T g = 267 K. After melt-quenching at liquid nitrogen temperature, a boson peak appears at about 16.5 cm-1 near and below T g and the intensity of quasi-elastic scattering related to structural relaxation increases markedly on heating. The crystalline racemic ketoprofen of "conformer A" shows the noncoincidence of mode frequencies below 200 cm-1 between Raman scattering spectrum and imaginary part of dielectric spectrum observed by THz-TDS.

Low-frequency vibrational properties of crystalline and glassy indomethacin probed by terahertz time-domain spectroscopy and low-frequency Raman scattering

“…The present result is consistent with a simulation study [33] and the experimental study of glassy sorbitol [38]. The experimental data and literature values of the boson peak frequency and shear modulus of several hydrogen bonded organic glass-forming materials including IMC are presented in Table 2 [39][40][41][42]. Different from the case of glycerol [40], which is a typical hydrogen bonded molecular glass former, the boson peak appears at a lower frequency in the IMC.…”

“…Comparison of boson peak frequencies of Raman scattering and shear modulus in hydrogen bonded organic glass-forming materials, glycerol, ketoprofen and indomethacin[39][40][41][42].…”

Terahertz time-domain spectroscopy and Raman scattering studies of incipient ferroelectric BaZrO3

“…By using the reflected or transmitted THz pulse from a sample, the dielectric property can observe directly without any assumption or Kramers-Kronig analysis [8,[9][10][11]. Permitivity in the terahertz region, especially, in far-IR, is dominantly determined by the ionic polarization which is derived from the optical phonons.…”

Broadband Terahertz Time-Domain and Low-Frequency Raman Spectroscopy of Crystalline and Glassy Pharmaceuticals

“…Peaks are described by spectral functions of dumped harmonic oscillators (DHO) to determine the mode frequency and damping of each mode. From these results and the reported results of DFT calculation and vibrational assignment [14], it is suggested that one possible origin of intense low-frequency peaks such as 1.38, 2.04 and 2.91 THz in a Raman scattering spectrum is the vibrations relate to hydrogen bonded ketoprofen dimers in the crystal structure [15].…”