Do homochiral aggregates have an entropic advantage?
Do homochiral aggregates have an entropic advantage?
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DOI：
10.1021/jp046478x
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发表时间：
2005-01-13
影响因子：
3.3
通讯作者：
Clemmer, DE
中科院分区：
文献类型：
--
作者：
Julian, RR;Myung, S;Clemmer, DE
目前的工作试图通过研究熵在这一过程中所起的作用来阐明控制手性构建块聚集成更大聚集体的基本原理。首先在一个简单的模型系统的范围内检查了熵效应，然后将结果与氨基酸簇的实验数据进行了比较。该模型系统预测，从对映体溶液形成特定结构的可能性更大，因为从外消旋溶液形成特定结构受到显著的熵障碍的阻碍。这些预测与实验结果符合得很好。在我们对所有氨基酸的簇的检查中，只有在对对映体溶液进行采样时才能发现异常丰富的簇。此外，大多数团簇都没有表现出对手性组成的偏好，这表明熵效应抵消了热焓的任何变化。尽管实验数据并不全面，但我们的结果强烈表明，与外消旋簇中的特异性相比，同手性簇中的特异性具有显著的优势。
The present work seeks to illuminate the underlying principles which control the aggregation of chiral building blocks into larger aggregates by examining the role that entropy plays in this process. Entropic effects are first examined within the confines of a simple model system, and the results are then compared to experimental data on clusters of amino acids. The model system predicts that the formation of a specific structure is more likely to occur from an enantiopure solution because forming a particular structure from a racemic solution is hindered by significant entropic barriers. These predictions are in good agreement with the experimental results. In our examination of clusters of all of the amino acids, clusters which are unusually abundant are found only when enantiopure solutions are sampled. Furthermore, the majority of all clusters exhibit no preference for chiral composition, suggesting that entropic effects negate any changes in enthalpy. Although the experimental data are not comprehensive, our results strongly suggest that specificity in homochiral clusters is entropically advantageous compared to specificity in racemic clusters.