Romanini Michela, Barrio María, Macovez Roberto, Ruiz-Martin María D, Capaccioli Simone, Tamarit Josep Ll
Grup de Caracterització de Materials, Universitat Politècnica de Catalunya, EEBE, Departament de Física, and Barcelona Research Center in Multiscale Science and Engineering, C. Eduard Maristany 10-14, E-08019, Barcelona, Spain.
Dipartimento di Fisica, Università di Pisa, and IPCF-CNR, Largo B. Pontecorvo 3, I-56127, Pisa, Italy.
Sci Rep. 2017 May 2;7(1):1346. doi: 10.1038/s41598-017-01464-2.
We probe the temperature- and pressure-dependent specific volume (v) and dipolar dynamics of the amorphous phase (in both the supercooled liquid and glass states) of the ternidazole drug (TDZ). Three molecular dynamic processes are identified by means of dielectric spectroscopy, namely the α relaxation, which vitrifies at the glass transition, a Johari-Goldstein β relaxation, and an intramolecular process associated with the relaxation motion of the propanol chain of the TDZ molecule. The lineshapes of dielectric spectra characterized by the same relaxation time (isochronal spectra) are virtually identical, within the studied temperature and pressure ranges, so that the time-temperature-pressure superposition principle holds for TDZ. The α and β relaxation times fulfil the density-dependent thermodynamic scaling: master curves result when they are plotted against the thermodynamic quantity Tv , with thermodynamic exponent γ approximately equal to 2. These results show that the dynamics of TDZ, a system characterized by strong hydrogen bonding, is characterized by an isomorphism similar to that of van-der-Waals systems. The low value of γ can be rationalized in terms of the relatively weak density-dependence of the dynamics of hydrogen-bonded systems.
我们探究了替硝唑药物（TDZ）非晶相（处于过冷液体和玻璃态）的比容（v）以及偶极动力学随温度和压力的变化情况。通过介电谱法识别出了三个分子动力学过程，即α弛豫（在玻璃化转变时发生玻璃化）、乔哈里-戈尔茨坦β弛豫以及与TDZ分子丙醇链弛豫运动相关的分子内过程。在研究的温度和压力范围内，具有相同弛豫时间的介电谱线形（等时谱）实际上是相同的，因此替硝唑遵循时间-温度-压力叠加原理。α和β弛豫时间符合密度依赖的热力学标度关系：当它们相对于热力学量Tv绘制时会得到主曲线，热力学指数γ约等于2。这些结果表明，以强氢键为特征的TDZ体系的动力学具有与范德华体系相似的同构性。γ值较低可以根据氢键体系动力学相对较弱的密度依赖性来解释。
