Coordinative Alignment in the Pores of MOFs for the Structural Determination of N‑, S‑, and P‑Containing Organic Compounds Including Complex Chiral Molecules

Coordinative alignment of target small molecules onto
a chiral
metal–organic framework (MOF-520)­provides a powerful method
to determine the structures of small molecules through single-crystal
X-ray diffraction (SXRD). In this work, the structures of 17 molecules
with eight new coordinating functionalities and varying size have
been determined by this method, four of which are complex molecules
being crystallized for the first time. The chirality of the MOF backbone
not only enables enantioselective crystallization of chiral small
molecules from a racemic mixture but also imposes diastereoselective
incorporation upon achiral molecules. Crystallographic studies assisted
by density functional theory (DFT) calculations indicate that the
stereoselectivity of MOF-520 not exclusively comes from the steric
confinement of the chiral pore environment but also from asymmetric
chemical bonding of the target molecules with the framework that is
able to provide sufficient energy difference between possible coordination
configurations.

目标小分子与手性金属-有机框架（MOF-520）的配位对齐提供了一种强大的方法，用以通过单晶X射线衍射（SXRD）确定小分子的结构。在本研究中，通过该方法确定了17种具有八种新型配位功能和不同尺寸的分子结构，其中四种为首次结晶的复杂分子。MOF-520骨架的手性不仅使得手性小分子可以从外消旋混合物中实现对映选择性结晶，而且还对非手性分子施加了非对映选择性引入。借助密度泛函理论（DFT）计算辅助的晶体学研究表明，MOF-520的立体选择性不仅源于手性孔隙环境的位阻限制，还源于目标分子与框架的异构化学键合，这种键合能够提供足够的能量差异，以区分可能的配位构型。