Structural Induction Effect of a Zwitterion Pyridiniumolate for Metal–Organic Frameworks

It
is still an enormous challenge to obtain the metal–organic
frameworks (MOFs) with specific properties by tuning their structures.
Here we first reported that the structures of MOFs could be tuned
by adding certain amount of zwitterion pyridiniumolate. To demonstrate
the inductive effect, two series of assembly experiments were performed
using different metal ions, namely, Cd­(II) and Mn­(II). The experimental
results revealed that the zwitterion pyridiniumloate only acted as
a structural induction agent (SIA), which did not exist in the aimed
compounds. The SIAs could effectively tune the framework aperture
or promote coordination and further tune the properties of MOFs without
any removal or exchange after the synthesis. Therefore, the results
could not only immensely expand the syntheses and structural diversity
of MOFs with the fixed metal ions and organic ligands but also afford
the possibility and effective convenience for tuning the properties
of MOFs in the functional material research fields.

通过调控结构来制备具备特定性能的金属有机框架（metal–organic frameworks, MOFs），仍是一项极具挑战性的研究课题。本研究首次报道，可通过添加一定量的两性离子型吡啶醇盐来调控MOFs的结构。为验证该诱导作用，本研究以镉(II)和锰(II)两种不同金属离子为金属源，开展了两系列组装实验。实验结果表明，该两性离子型吡啶醇盐仅作为结构诱导剂（SIA）参与合成过程，并未留存于最终的目标产物之中。该类结构诱导剂可在合成结束后无需额外脱除或置换的情况下，有效调控MOFs的框架孔径、促进配位作用，进而实现MOFs性能的精准调控。因此，本研究成果不仅极大丰富了固定金属离子与有机配体体系下MOFs的合成路径与结构多样性，同时也为功能材料研究领域中MOFs的性能调控提供了可行方案与便捷途径。