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Single Crystal Growth Kinetics of Two Polymorphs of Piracetam
Crystal Growth & Design ( IF 3.2 ) Pub Date : 2021-09-21 , DOI: 10.1021/acs.cgd.1c00455
Aisling Lynch 1 , Rodrigo Soto 1 , Åke Rasmuson 1, 2
Affiliation  

The crystal growth of single crystals of the metastable and stable polymorph of piracetam (PCM) in ethanol and isopropanol has been investigated using the rotating disk (RD) technique. A number of seed crystals were attached onto a disk that was rotated in a supersaturated solution. The crystal growth rate in length and width directions was measured for each individual crystal, and the growth rates were also extracted for the (011) crystal facet. The metastable FII form was found to exhibit a faster growth rate than the thermodynamically stable FIII form. The impact of solvents, supersaturation, temperature, and crystal seed properties was studied. Within a range of experimental conditions, the growth kinetics of both polymorphs were strongly affected by the temperature and, to a lesser degree, by the solvent choice. For both polymorphs, faster growth rates were obtained in ethanol than in isopropanol. The growth rate exhibits a fairly linear increase with increasing supersaturation for both polymorphic forms, but the slope is different. By fitting the Burton Cabrera Frank (BCF) and Birth and Spread (B + S) theories to the growth rate data at different supersaturations and temperatures in ethanol, a lower interfacial energy and a longer mean diffusion distance on the surface is obtained for the metastable polymorph compared to the stable form. The crystal growth rates measured in the present study are in good agreement with the data previously determined using isothermal desupersaturation experiments (ISD), and so are the fundamental parameters estimated by the BCF and the B + S theories.

中文翻译:

拉西坦两种多晶型物的单晶生长动力学

已使用转盘 (RD) 技术研究了吡拉西坦 (PCM) 在乙醇和异丙醇中的亚稳态和稳定多晶型物单晶的晶体生长。许多晶种附着在一个在过饱和溶液中旋转的圆盘上。测量每个晶体的长度和宽度方向的晶体生长速率,并且还提取了 (011) 晶面的生长速率。发现亚稳态 FII 形式比热力学稳定的 FIII 形式表现出更快的生长速率。研究了溶剂、过饱和度、温度和晶种性质的影响。在一系列实验条件下,两种多晶型物的生长动力学都受到温度的强烈影响,并在较小程度上受到溶剂选择的影响。对于两种多晶型,在乙醇中获得比在异丙醇中更快的生长速率。随着两种多晶型物的过饱和度的增加,生长速率呈现出相当线性的增加,但斜率不同。通过将 Burton Cabrera Frank (BCF) 和诞生和传播 (B + S) 理论与乙醇中不同过饱和度和温度下的生长速率数据拟合,亚稳态得到较低的界面能和较长的表面平均扩散距离多晶型与稳定型相比。本研究中测量的晶体生长速率与先前使用等温减饱和实验 (ISD) 确定的数据非常一致,BCF 和 B + S 理论估计的基本参数也是如此。随着两种多晶型物的过饱和度的增加,生长速率呈现出相当线性的增加,但斜率不同。通过将 Burton Cabrera Frank (BCF) 和诞生和传播 (B + S) 理论与乙醇中不同过饱和度和温度下的生长速率数据拟合,亚稳态得到较低的界面能和较长的表面平均扩散距离多晶型与稳定型相比。本研究中测量的晶体生长速率与先前使用等温去饱和实验 (ISD) 确定的数据非常一致,BCF 和 B + S 理论估计的基本参数也是如此。随着两种多晶型物的过饱和度的增加,生长速率呈现出相当线性的增加,但斜率不同。通过将 Burton Cabrera Frank (BCF) 和诞生和传播 (B + S) 理论与乙醇中不同过饱和度和温度下的生长速率数据拟合,亚稳态得到较低的界面能和较长的表面平均扩散距离多晶型与稳定型相比。本研究中测量的晶体生长速率与先前使用等温减饱和实验 (ISD) 确定的数据非常一致,BCF 和 B + S 理论估计的基本参数也是如此。通过将 Burton Cabrera Frank (BCF) 和诞生和传播 (B + S) 理论与乙醇中不同过饱和度和温度下的生长速率数据拟合,亚稳态得到较低的界面能和较长的表面平均扩散距离多晶型与稳定型相比。本研究中测量的晶体生长速率与先前使用等温减饱和实验 (ISD) 确定的数据非常一致,BCF 和 B + S 理论估计的基本参数也是如此。通过将 Burton Cabrera Frank (BCF) 和诞生和传播 (B + S) 理论与乙醇中不同过饱和度和温度下的生长速率数据拟合,亚稳态得到较低的界面能和较长的表面平均扩散距离多晶型与稳定型相比。本研究中测量的晶体生长速率与先前使用等温减饱和实验 (ISD) 确定的数据非常一致,BCF 和 B + S 理论估计的基本参数也是如此。
更新日期:2021-10-06
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