Gould Ashah M, Schalk Danielle R, Fleagle Molly E, Wheeler Kraig A
Department of Chemistry, Whitworth University, 300 West Hawthorne Road, Spokane, Washington 99251, United States.
Cryst Growth Des. 2024 Apr 15;24(9):3967-3976. doi: 10.1021/acs.cgd.4c00307. eCollection 2024 May 1.
Understanding the interplay of structural features responsible for molecular assembly is essential for molecular crystal engineering. When assembling molecules with encoded motifs, supramolecular strategies almost always include robust directional nonbonded contacts. Quasiracemic materials, considered near racemates since cocrystallization occurs with chemically unique components, lack a molecular framework or functional group restrictions, highlighting the importance of molecular shape to molecular assembly. Recently, our group reported quasiracemates derived from benzoyl leucine/phenylalanine derivatives with two points of chemical difference. In this study, we modified the chemical framework with valine and increased the scope of the work by imposing a larger variance in the side chain substituents. Pairing a CF component with quasienantiomers that differ iteratively from hydrogen to -butyl offers an important view into the supramolecular landscape of these materials. Single-crystal X-ray crystallography and lattice energy assessments, coupled with conformational and crystal structure similarity searches, show an elevated degree of isomorphism for many of the targeted 17 racemates and quasiracemates. These benzoyl amino acid molecular architectures create extended hydrogen-bond patterns in the crystal that provide enhanced opportunities to study the shape space and molecular recognition profiles for a diverse family of quasienantiomeric components.
了解负责分子组装的结构特征之间的相互作用对于分子晶体工程至关重要。在用编码基序组装分子时，超分子策略几乎总是包括强大的定向非键相互作用。准外消旋材料由于与化学上独特的组分发生共结晶而被视为接近外消旋体，缺乏分子框架或官能团限制，突出了分子形状对分子组装的重要性。最近，我们小组报道了源自具有两点化学差异的苯甲酰亮氨酸/苯丙氨酸衍生物的准外消旋体。在本研究中，我们用缬氨酸修饰了化学框架，并通过在侧链取代基中引入更大的差异来扩大工作范围。将一个CF组分与从氢到丁基迭代不同的准对映体配对，为这些材料的超分子格局提供了重要视角。单晶X射线晶体学和晶格能评估，结合构象和晶体结构相似性搜索，表明许多目标17种外消旋体和准外消旋体具有较高程度的同构性。这些苯甲酰氨基酸分子结构在晶体中形成扩展的氢键模式，为研究多种准对映体组分的形状空间和分子识别概况提供了更多机会。
