Different dynamics of chiral and racemic (L- and DL-) serine crystals: Evidenced by incoherent inelastic neutron and Raman scattering
Different dynamics of chiral and racemic (L- and DL-) serine crystals: Evidenced by incoherent inelastic neutron and Raman scattering
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DOI：
10.1021/ja073351n
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发表时间：
2007-09-12
影响因子：
15
通讯作者：
Juranyi, Fanni
中科院分区：
文献类型：
--
作者：
Bordallo, Heloisa N.;Kolesov, Boris A.;Juranyi, Fanni
对手性与外消旋氨基酸形式的兴趣源于它们与导致完全不同的物理行为的堆积排列相关的不同固态性质。在这里，我们专注于不同的动态特性的手性（L-型）和外消旋（DL-型）晶体的丝氨酸，（C3 H7 NO3）。通过测量非相干非弹性中子和拉曼散射，我们可以估计L-丝氨酸在150 K附近的一个微妙的动力学跃迁。从我们的光谱研究证明的L-和DL-丝氨酸的晶体的动力学性质的差异是在一个很好的协议与不同的Cp（T）的依赖性和不同的结构应变的两种形式的冷却。尽管堆积密度较高，但L-丝氨酸晶体中的分子碎片比DL-丝氨酸中的分子碎片更动态，这在非相干非弹性中子和拉曼光谱中以及在较高的热容、较高的热膨胀系数或NMR光谱中表现出来。
Interest in chiral versus racemic amino acid forms stems from their different solid-state properties associated to the packing arrangement that leads to starkly different physical behavior. Here we focus on the different dynamic properties of the chiral (L-form) and racemic (DL-form) crystals of serine, (C3H7NO3). Measuring incoherent inelastic neutron and Raman scattering over a wide temperature range we could assess a subtle dynamical transition in L-serine near 150 K. The difference in the dynamic properties of the crystals of L- and DL-serine evidenced from our spectroscopic studies is in a good agreement with the different C p (T ) dependences and different structural strain of the two forms on cooling. Despite a higher bulk density, the molecular fragments in the crystals of L-serine are more dynamic than in DL-serine, and this manifests itself in the incoherent inelastic neutron and Raman spectra, as well as in a higher heat capacity, a higher thermal expansion coefficient, or in the NMR-spectra.