A Zirconium Macrocyclic Metal–Organic Framework with Predesigned Shape‐Persistent Apertures

Abstract

A microporous metal-organic framework (MOF) was synthesized from [Zr O (OH) (C H COO) ] clusters and a triacid ligand based on a shape-persistent arylene ethynylene macrocycle. This framework, dubbed Zr-MCMOF, is held together by metal-ligand coordination and multiple weak interactions: hydrogen bonding, [π⋅⋅⋅π] stacking, and [C-H⋅⋅⋅π] interactions. The rigid ligand has a 9 Å-wide central void, which serves as a predesigned aperture for the 1D channels; all of the porosity of Zr-MCMOF comes from the ligand. The resulting framework possesses high hydrolytic and thermal stability and a flexible structure unique among Zr-based MOFs.

The Organic Secondary Building Unit: Strong Intermolecular π Interactions Define Topology in MIT-25, a Mesoporous MOF with Proton-Replete Channels

“…Although the formation of π-interacting motifs provides overall stabilization, as seen with MIT-26 and numerous other examples, these studies emphasize the importance of accessing oxidized species as well as delocalizing the holes to stabilize organic SBUs. These principles are illustrated in MIT-25 , whose unique mesoporous structure and new topology arise only because of the organic SBU.…”

“…MIT-25 exhibits permanent 26.4 Å × 30.5 Å mesopores running parallel to smaller pores occluded by hydronium ions. Controlling the topology by employing π-stacked organic supramolecular building blocks (i.e., organic SBUs) serves as a powerful paradigm for the design of novel hybrid frameworks.…”

Cyclotetrabenzoin Acetate: A Macrocyclic Porous Molecular Crystal for CO2 Separations by Pressure Swing Adsorption**

“…The practical applications of pure PMCs are restricted due to their structural instability, which leads to the loss of porosity. Conventional strategies to incorporate the cavities of porous molecules into solid materials can be briefly summarized: (1) frameworks connected by supramolecular interactions 22,31 or metalligand coordination bonds, [32][33][34][35] (2) organic polymers or porous networks anchored by porous molecules covalently, 36,37 and (3) PMCs dispersed as porous additives in organic polymers. [38][39][40] Coskun and coworkers have prepared a conjugated microporous polymer with one-dimensional (1D) channels based on the cross-coupling of pillar [5]arene, and used it in C3H8/CH4 separation.…”

Competing Allosteric Mechanisms for Coordination-Directed Conformational Changes of Chiral Stacking Structures with Aromatic Rings

“…Stacking interactions are some of the most important noncovalent interactions, which yield π-electron systems of aromatic molecules with intriguing electronic and photophysical properties. − Typical of noncovalent interactions, interactions of aromatic stacks are weak and are formed reversibly in a dynamic equilibrium, with some tendency to give the energetically favored stacking arrangements . Conversely, metal–ligand interactions sometimes trigger energetically unfavorable stacking interactions. − …”