...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >The infrared spectrum of solid L-alanine: Influence of pH-induced structural changes
【24h】

The infrared spectrum of solid L-alanine: Influence of pH-induced structural changes

机译：固体L-丙氨酸的红外光谱：pH诱导的结构变化的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The influence of the pH on the infrared spectrum Of L-alanine has been analyzed by diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. The amino acid was precipitated from aqueous solutions and dried at 36.5 degrees C, in order to stabilize cationic L-alanine or alaninium [CH3CH(NH3+)COOH] at pH 1, the zwitterionic form [CH3CH(NH3+)COO-] at pH 6, and anionic L-alanine or alaninate [CH3CH(NH2)COO-] at pH 13. New insight on the specific inter and intramolecular interactions in the different forms of L-alanine was reached by a novel methodological approach: an infrared technique not used before to analyze solid amino acid samples (DRIFTS), in combination with a detailed analysis based on spectral deconvolution. The frequency ranges of interest include the carbonyl/carboxyl stretching and amine deformation modes and the OH/NH stretching modes. It was shown that intermolecular hydrogen bonds between the NH3+ and COO- groups are predominant in the zwitterionic form, whereas in cationic L-alanine, H bonds between the COOH groups are responsible for the formation of dimers. In anionic L-alanine, only strong electrostatic interactions between the COOgroups and Na+ ions are proposed, evidencing the relevant role of the counterion.
机译：通过漫反射红外傅里叶变换（DRIFT）光谱分析了pH对L-丙氨酸红外光谱的影响。从水溶液中沉淀出氨基酸，并在36.5摄氏度下干燥，以使阳离子L-丙氨酸或铝铵[CH3CH（NH3 +）COOH]稳定在pH 1，两性离子形式[CH3CH（NH3 +）COO-]在pH 6时稳定，以及在pH 13时的阴离子L-丙氨酸或丙氨酸盐[CH3CH（NH2）COO-]。通过一种新颖的方法学方法，对不同形式的L-丙氨酸中特定的分子间和分子内相互作用进行了新的了解：未使用红外技术在分析固体氨基酸样品（DRIFTS）之前，结合基于光谱解卷积的详细分析。感兴趣的频率范围包括羰基/羧基拉伸和胺变形模式以及OH / NH拉伸模式。结果表明，两性离子形式的NH3 +和COO-基团之间的分子间氢键占主导地位，而在阳离子L-丙氨酸中，COOH基团之间的H键负责形成二聚体。在阴离子L-丙氨酸中，仅提出了COO基团与Na +离子之间的强静电相互作用，证明了抗衡离子的相关作用。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号