Wen-Yang Gao

Crystal Engineering of a Microporous, Catalytically Active fcu Topology MOF Using a Custom‐Designed Metalloporphyrin Linker

A major driving force behind the recent surge of interest in metal–organic frameworks (MOFs) lies with their amenability to design using crystal engineering strategies. In particular, MOFs with specific composition and topology can be targeted by judicious selection of organic linkers and metal-based molecular building blocks (MBBs) that serve as nodes. Furthermore, their modular nature means that prototypal MOFs can serve as blueprints or platforms for a plethora of derivatives with controlled pore size and surface area, as exemplified by the practice of “reticular synthesis”. Such features make MOFs stand out over traditional porous materials, and afford them with potential for use in gas storage, separation, CO2 capture, [6] sensor, catalysis, and other areas. High-symmetry MOFs based upon high-connectivity polyhedral cage MBBs that are in effect supermolecular building blocks (SBBs) can provide exquisite control over structure because of their high connectivity and also afford the features of confined nanospace and extra-large surface area. Such MOFs have afforded superior performance in the context of gas storage for hydrogen, methane, CO2, and other gas molecules. 11,12] The nature of the nanospace in SBB-based MOFs is such that they can encapsulate catalytically active species, for example, organometallics, polyoxometallates, metalloporphyrins (porph@MOMs), and enzymes. Along with encapsulation of catalysts, it is possible to generate porphyrin-walled MOFs by customdesigning metalloporphyrin moieties so that they can serve as vertices and/or edges and/or faces. In principle, the metal clusters residing on the vertices could also contribute as active sites to achieve an even higher density of active sites than that of porph@MOMs. Polyhedral MOFs are therefore attractive targets as catalyst supports for heterogeneous catalysis. However, although metallosalens and metalloporphyrins have been utilized as linkers for catalytically active MOFs and polyhedral cage-containing metal–metalloporphyrin frameworks exist, MOFs sustained by catalytically active metalloporphyrin linkers and catalytically active MBBs remain unexplored. Herein, we report such a MOF that based upon a previously reported fcu topology net built from 12-connected cubohemioctahedral SBBs of formula [Co2(m2-H2O)(H2O)4]6(bdc)12 and benzoimidephenanthroline tetracarboxylate (bipa-tc) linkers (Scheme 1a), fcu-MOF-1. The new com-

Vertex-directed self-assembly of a high symmetry supermolecular building block using a custom-designed porphyrin

Metal–organic materials that are constructed from polyhedral supermolecular building blocks, SBBs, can offer exquisite control over structure and afford useful features such as multiple cage types and relatively narrow pores. This contribution describes how a custom-designed porphyrin, tdcpp, self-assembles with M(II) (M = Zn, Cd) cations to generate the first examples of SBBs that are uniform polyhedra based upon a porphyrin molecular building block, MBB. The faces of tdcpp moieties link triangular M2(CO2)3 or M(CO2)3 moieties to form small cubicuboctahedral SBBs that are in turn fused to adjacent SBBs at the opposite face of each tdcpp moiety. The resulting high symmetry augmented pcu topology networks, MMPF-4 (M = Zn) and MMPF-5 (M = Cd), exhibit two distinct polyhedral cages and are permanently microporous with selective CO2 uptake.

Inserting CO2 into Aryl C−H Bonds of Metal–Organic Frameworks: CO2 Utilization for Direct Heterogeneous C−H Activation

Described for the first time is that carbon dioxide (CO2 ) can be successfully inserted into aryl C-H bonds of the backbone of a metal-organic framework (MOF) to generate free carboxylate groups, which serve as Brønsted acid sites for efficiently catalyzing the methanolysis of epoxides. The work delineates the very first example of utilizing CO2 for heterogeneous C-H activation and carboxylation reactions on MOFs, and opens a new avenue for CO2 chemical transformations under mild reaction conditions.

A new microporous carbon material synthesized via thermolysis of a porous aromatic framework embedded with an extra carbon source for low-pressure CO2 uptake

Pre-introducing an extra carbon source into the porous aromatic framework of PAF-1 followed by thermolysis affords a new microporous carbon material, which demonstrates a CO2 uptake capacity of 93 cm(3) g(-1) (equivalent to 4.1 mmol g(-1) or 18.2 wt%) at 295 K and 1 bar.

Interpenetrating Metal–Metalloporphyrin Framework for Selective CO2 Uptake and Chemical Transformation of CO2

Herein we report a robust primitive cubic (pcu)-topology metal-metalloporphyrin framework (MMPF), MMPF-18, which was constructed from a ubiquitous secondary building unit of a tetranuclear zinc cluster, Zn4(μ4-O)(-COO)6, and a linear organic linker of 5,15-bis(4-carboxyphenyl)porphyrin (H2bcpp). The strong π-π stacking from porphyrins and the lengthy H2bcpp ligand affords a 4-fold-interpenetrating network along with reduced void spaces and confined narrow channels. Thereby, MMPF-18 presents segmented pores and high-density metalloporphyrin centers for selective CO2 uptake over CH4 and size-selective chemical transformation of CO2 with epoxides forming cyclic carbonates under ambient conditions.

Porous double-walled metal triazolate framework based upon a bifunctional ligand and a pentanuclear zinc cluster exhibiting selective CO2 uptake.

The self-assembly of a custom-designed bifunctional ligand featuring both 1,2,3-triazolate and carboxylate donor groups with a pentanuclear zinc cluster generated in situ affords a double-walled metal triazolate framework (MTAF) material, MTAF-1 (Zn(5)(μ(3)-O)(2)(C(9)N(3)H(5)O(2))(5)(H(+))(4)(H(2)O)(17)(C(3)H(7)NO)(10)), which exhibits a surface area of 2300 m(2)/g and demonstrates interesting selective CO(2) uptake performances.

Imparting amphiphobicity on single-crystalline porous materials

The sophisticated control of surface wettability for target-specific applications has attracted widespread interest for use in a plethora of applications. Despite the recent advances in modification of non-porous materials, surface wettability control of porous materials, particularly single crystalline, remains undeveloped. Here we contribute a general method to impart amphiphobicity on single-crystalline porous materials as demonstrated by chemically coating the exterior of metal-organic framework (MOF) crystals with an amphiphobic surface. As amphiphobic porous materials, the resultant MOF crystals exhibit both superhydrophobicity and oleophobicity in addition to retaining high crystallinity and intact porosity. The chemical shielding effect resulting from the amphiphobicity of the MOFs is illustrated by their performances in water/organic vapour adsorption, as well as long-term ultrastability under highly humidified CO2 environments and exceptional chemical stability in acid/base aqueous solutions. Our work thereby pioneers a perspective to protect crystalline porous materials under various chemical environments for numerous applications.

Two rare indium-based porous metal–metalloporphyrin frameworks exhibiting interesting CO2 uptake

Two rare indium-based porous metal–metalloporphyrin frameworks (MMPFs), MMPF-7 and MMPF-8, were constructed by self-assembly of In(III) and two custom-designed porphyrin–tetracarboxylate ligands. MMPF-7 and MMPF-8 possess the pts topology and exhibit interesting CO2 adsorption properties.

Precise Molecular Fission and Fusion: Quantitative Self-Assembly and Chemistry of a Metallo-Cuboctahedron†

Inspiration for molecular design and construction can be derived from mathematically based structures. In the quest for new materials, the adaptation of new building blocks can lead to unexpected results. Towards these ends, the quantitative single-step self-assembly of a shape-persistent, Archimedean-based building block, which generates the largest molecular sphere (a cuboctahedron) that has been unequivocally characterized by synchrotron X-ray analysis, is described. The unique properties of this new construct give rise to a dilution-based transformation into two identical spheres (octahedra) each possessing one half of the molecular weight of the parent structure; concentration of this octahedron reconstitutes the original cuboctahedron. These chemical phenomena are reminiscent of biological fission and fusion processes. The large 6 nm cage structure was further analyzed by 1D and 2D NMR spectroscopy, mass spectrometry, and collision cross-section analysis. New routes to molecular encapsulation can be envisioned.

Porous metal–organic framework based on a macrocyclic tetracarboxylate ligand exhibiting selective CO2 uptake

A two-fold interpenetrating microporous metal–organic framework, MMCF-1, has been constructed via the self-assembly of a custom-designed macrocyclic tetracarboxylate ligand and Cd(II), and it exhibits interesting selective uptake of CO2 over N2.