A series of fcu-MOFs based on rare-earth (RE) metals and linear fluorinated/nonfluorinated, homo/heterofunctional ligands were targeted and synthesized. This particular fcu-MOF platform was selected because of its unique structural characteristics combined with the ability/potential to dictate and regulate its chemical properties (e.g., tuning of the electron-rich RE metal ions and high localized charge density, a property arising from the proximal positioning of polarizing tetrazolate moieties and fluoro-groups that decorate the exposed inner surfaces of the confined conical cavities). These features permitted a systematic gas sorption study to evaluate/elucidate the effects of distinctive parameters on CO2-MOF sorption energetics. Our study supports the importance of the synergistic effect of exposed open metal sites and proximal highly localized charge density toward materials with enhanced CO2 sorption energetics.

The potential of the molecular-building-block (MBB) approach for the assembly and development of functional solid-state porous materials has already been recognized. [1] This approach offers a prospective avenue toward the design and construction of novel materials; that is, desired properties can be incorporated at the design stage. These properties are required to address the myriad technological challenges that face us, including hydrogen storage for fuel applications. In metal-ligand directed assembly, the MBB approach has been adopted for the synthesis of functional metal-organic assemblies (MOAs), which range from discrete (metal-organic polyhedra) to 3D (metal-organic frameworks (MOFs)). Accordingly, various applications, including nonlinear optics (NLO), magnetism, catalysis, and gas storage, were revealed for MOFs. [2,3] These MOFs have proven exceptional owing to their facile tunability (alteration in pore size and functionality), a feature dependent on the rigidity, modularity, and control of the MBBs. Therefore, prior to the assembly process, it is essential that the MBBs possess certain attributes for the construction of targeted structures: each must be rigid, impart the desired directionality, and possess the necessary shape and geometry for that structure.Organic chemistry would seem to offer a vast repertoire to be employed as MBBs, because organic molecules can be designed to contain these features. Nevertheless, organicmolecule-based MBBs with high connectivity are not common, and their assembly into crystalline porous organic frameworks remains a challenge.[4] As such, alternative routes have been pursued combining organic MBBs and inorganic MBBs derived from metal-ligand coordination. Unlike organic MBBs, which are selected already possessing the desired features, typically inorganic MBBs are formed in situ. As a result, reaction conditions to generate a specific inorganic MBB consistently in situ are vital; once established, desired MOAs can be designed and (potentially) assembled by judicious choice of organic ligands. It is clear that continuous development and isolation of novel MBBs will eventually facilitate the rational construction of targeted functional MOAs, an example of design versus serendipity.Strategies based on the MBB approach have already shown promise toward the design and construction of MOAs, and, accordingly, some basic guidelines have been derived: [1] 1) It is essential that the desired inorganic building blocks can be targeted. 2) The organic linker must have specific functionalities that give rise to the desired shape, geometry, and rigidity upon coordination. 3) Reaction conditions must introduce the ability to generate crystalline materials, a result that is vital for structural analysis and correlations between structure and building units. 4) It is accepted that the assembly of simple building blocks, in the absence of any altering agent such as a template or structure directing agent (SDA), will lead to the construction of the default structure relative to...

The extra-large cavities of zeolite-like metal-organic frameworks (ZMOFs) offer great potential for their exploration in applications pertinent to larger molecules, like porphyrins. The anionic nature of the framework allowed for facile in situ encapsulation of a cationic free-base porphyrin, and the alpha-cage of our (In-imidazoledicarboxylate)-based rho-ZMOF is ideally suited to the isolation of one porphyrin molecule per cage, which prevents the oxidative self-degradation associated with self-dimerization common in homogeneous catalysis and upon aggregation in solid supports like mesoporous silicates or polymers. The encapsulation of a free-base porphyrin [5,10,15,20-tetrakis(1-methyl-4- pyridinio)porphyrin] and the stability of the rho-ZMOF to metalation conditions, allows for the preparation of a variety of metalloporphyrins (i.e., Mn, Cu, Co, Zn ions) with the ZMOF serving as a platform. The Mn-metallated porphyrin encapsulated in rho-ZMOF shows catalytic activity toward the oxidation of cyclohexane, with turn-over numbers, to the best of our knowledge, higher than reported for similar heterogeneous systems, and our system can be recycled up to 11 cycles, which represents a longer lifetime than reported for any other system.

Two novel porous anionic zeolite-like metal-organic frameworks, rho-ZMOF and sod-ZMOF, have been synthesized by metal-ligand-directed assembly of rigid and directional tetrahedral building units, InN4 synthesized in situ, and doubly deprotonated bis(bidentate) imidazoledicarboxylic acid ligands (HImDC) in the presence of different structure directing agents (SDAs).

Using commercially activated carbon, we developed a simple and effective direct chemical oxidation route to prepare good biocompatible multicolor photoluminescent carbon dots.