Understanding the structural landscape of Mn-based MOFs formed with hinged pyrazole carboxylate linkers
Understanding the structural landscape of Mn-based MOFs formed with hinged pyrazole carboxylate linkers
复制标题
了解由铰链吡唑羧酸酯连接体形成的锰基 MOF 的结构景观
DOI：
10.1039/d3ce00881a
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发表时间：
2023
期刊：
影响因子：
3.1
通讯作者：
Smernik J
中科院分区：
文献类型：
--
作者：
Smernik J
具有合成后金属化能力的金属有机骨架（mof）作为催化金属的载体已经引起了人们的极大兴趣。mn基MOF MnMOF-1 ([Mn3（L2Me)3]，其中L2Me =双-（4-羧基苯基-3,5-二甲基吡唑基）甲烷）已成为研究PSMet的一个范例。本文研究了由相关的柔性双异位吡唑羧酸键合成mn基mof，以及形成具有类似四异位铰接连接的mof。我们首次证明MnMOF-1可能是一个动力学相或亚稳相，并且新发现的二维层状材料（MnMOF-2D）是这种金属连接剂组合的热力学有利产物。具有较短连接体的MnMOF-1结构的形成受到空间冲突的阻碍，从而阻碍了Mn3簇的形成。这一观察结果促使使用密度泛函理论（DFT）模拟，表明目标材料非常致密，高度应变，因此在能量上是不利的，但潜在地，假设具有较长苯乙基间隔的MnMOF-1结构在能量上是可行的。最后，具有较短柔性链接的二维mof的优势促使我们使用四异位铰接连接体形成三维框架，成功合成了两种新型多孔三维mn基mof， MnMOF-L4和MnMOF-L5。这些结果表明，由柔性非线性连接体形成的网状mof的合成是具有挑战性的。
Metal–organic frameworks (MOFs) capable of post-synthetic metalation (PSMet) have garnered significant interest as supports for catalytic metals. The Mn-based MOF, MnMOF-1 ([Mn3(L2Me)3] where L2Me = bis-(4-carboxyphenyl-3,5-dimethylpyrazolyl)methane), has been an exemplar for studying PSMet. Herein we investigate the synthesis of Mn-based MOFs from related flexible ditopic pyrazole carboxylate links, along with the formation of MOFs with similar tetratopic hinged linkers. We show for the first time that MnMOF-1 is likely a kinetic or metastable phase and a newly identified 2D layered material (MnMOF-2D) is the thermodynamically favoured product for this metal–linker combination. Formation of a MnMOF-1 structure with shorter linkers is thwarted by steric clashes that preclude the formation of the Mn3 cluster. This observation prompted the use of density functional theory (DFT) simulations that showed the target material to be very dense, highly strained and thereby energetically unfavourable, but potentially, a hypothetical MnMOF-1 structure with a longer phenylethynyl spacer would be energetically feasible. Finally, the predominance of 2D MOFs formed with shorter flexible links encouraged us to use tetratopic hinged linkers to form 3D frameworks, which was vindicated by the successful synthesis of two new porous 3D Mn-based MOFs, MnMOF-L4 and MnMOF-L5. These results highlight that reticular synthesis of MOFs formed with flexible, non-linear linkers is challenging.