Altering the solubility of metal–organic polyhedra via pendant functionalization of Cp₃Zr₃O(OH)₃ nodes

Abstract

A new method to tune solubility of ZrMOPs via node-modification.

Phase-Pure Zirconium Metal–Organic Polyhedra Enabled by a Ligand Substitution Strategy

“…Recent work has suggested that ZrMOP tetrahedra are kinetic products, while lanterns are thermodynamically favored, in certain conditions. , This feature was exploited to isolate phase-pure [ZrMOP-biphenyl]­OTf X materials, where [tetZrMOP-biphenyl]­OTf 4 was isolated with a reaction time of only 20 min, and lanterns were present with any reaction time >30 min. To isolate phase-pure [lanZrMOP-biphenyl]­OTf 2 in good yields, the reaction was allowed to run for 20 h. The reason that the addition of water was not used to control phase purity in this system is that the biphenyl ligand is poorly soluble even in DMF, and in water/DMF mixtures, the solubility is even lower to the extent that self-assembly is hindered.…”

“…In addition, research into MOPs is often motivated by their higher solubilities relative to MOFs because they are molecular in nature. 24,25 ZrMOPs have shown stability in both basic and acidic media and at temperatures up to 300 °C. 26,27 The synthesis of ZrMOPs can be done under atmospheric conditions and requires only zirconocene dichloride with a simple dicarbox-ylate ligand in addition to the solvent, making the process both easy and inexpensive.…”

“…Although metal–organic materials are tunable and may exhibit high surface areas, many suffer from hydrolytic and/or thermal instability. − Zirconium-based MOPs are notable among these materials for their high stabilities, high-yielding syntheses, and low-cost building blocks. In addition, research into MOPs is often motivated by their higher solubilities relative to MOFs because they are molecular in nature. , ZrMOPs have shown stability in both basic and acidic media and at temperatures up to 300 °C. , The synthesis of ZrMOPs can be done under atmospheric conditions and requires only zirconocene dichloride with a simple dicarboxylate ligand in addition to the solvent, making the process both easy and inexpensive . For these reasons, ZrMOPs have been studied to address a wide range of applications including sensing, − catalysis, − biomedicine, − guest capture, , and gas separation/storage. − …”

Clickable Norbornene-Based Zirconium Carboxylate Polyhedra

“…11−18 Although a general feature of these self-assemblies is that they possess modular syntheses, it should be noted that ligand modifications may require multistep, lowyielding syntheses and challenging purifications. 19,20 Nonetheless, there are many examples of functionalizations, for instance, on the well-studied copper isophthalate paddlewheel-based MOPs, 21−26 and platinum or palladium pyridyl cages and metallacycles. 9,27 The ligand functionalization strategy may be generalized beyond these cores, which suffer from poor hydrolytic stability 28,29 and high cost, respectively.…”

“…When these building blocks are modified in ways that do not disrupt coordination, the resulting metallacycles or cages can be decorated with a wide variety of functional groups. Thus, ligand functionalization has been explored extensively by Stang, Fujita, Yang, and more as an effective strategy for altering the physicochemical properties of the resultant MOPs. − Although a general feature of these self-assemblies is that they possess modular syntheses, it should be noted that ligand modifications may require multistep, low-yielding syntheses and challenging purifications. , Nonetheless, there are many examples of functionalizations, for instance, on the well-studied copper isophthalate paddlewheel-based MOPs, − and platinum or palladium pyridyl cages and metallacycles. , The ligand functionalization strategy may be generalized beyond these cores, which suffer from poor hydrolytic stability , and high cost, respectively.…”