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.

通过在手性金属-有机框架（MOF-520）上对目标小分子的协同对齐，提供了一种强大的方法以确定小分子的结构，该方法基于单晶X射线衍射（SXRD）。在本研究中，通过此方法确定了17种分子（包括八种新的配位功能性和不同尺寸的分子）的结构，其中四种是首次结晶的复杂分子。MOF骨架的手性不仅使得从外消旋混合物中结晶手性小分子成为可能，而且还对非手性分子施加了立体选择性结合。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道环境的位阻限制，而且还源于目标分子与框架之间的非对称化学键合，这种键合能够提供足够大的能量差异，以区分可能的配位构型。