van Gestel Jeroen
Physical Chemistry and Molecular Thermodynamics Group, DelftChemTech, Technische Universiteit Delft, Julianalaan 136, 2628 BL, Delft, The Netherlands.
J Phys Chem B. 2006 Mar 9;110(9):4365-70. doi: 10.1021/jp056680f.
We present a theoretical treatment describing the conformational state of helical supramolecular polymers that consist of three types of monomer: right-handed and left-handed chiral monomers and achiral ones. We find that chirality amplification of the majority-rules type, that is, a disproportionately large shift in the helix screw sense due to a small enantiomeric excess, can occur in these polymers. The strength of the chirality amplification depends on the free-energy penalty of a helix reversal along the self-assembled chain and on that of a mismatch between the conformation of a bond and the preferred conformation of the preceding monomer. It turns out that the impact of achiral monomers also depends on these two parameters. For high values of these free energies, the net helicity does not change much from the situation where no achiral material is present. However, if the free-energy penalties are not both large, the impact of the achiral monomers on the conformational state of the aggregates can be quite substantial.
我们提出了一种理论处理方法，用于描述由三种类型的单体组成的螺旋超分子聚合物的构象状态：右手性和左手性手性单体以及非手性单体。我们发现，在这些聚合物中会出现多数规则类型的手性放大，即由于少量对映体过量导致螺旋螺旋方向出现不成比例的大偏移。手性放大的强度取决于沿自组装链的螺旋反转的自由能惩罚以及键的构象与前一个单体的优选构象之间不匹配的自由能惩罚。事实证明，非手性单体的影响也取决于这两个参数。对于这些自由能的高值，净螺旋度与不存在非手性材料的情况相比变化不大。然而，如果自由能惩罚并非都很大，非手性单体对聚集体构象状态的影响可能相当大。
