Large Cages of Zeolitic Imidazolate Frameworks.

The design and synthesis of permanently porous materials with extended cage structures is a long-standing challenge in chemistry. In this Account, we highlight the unique role of zeolitic imidazolate frameworks (ZIFs), a class of framework materials built from tetrahedral nodes connected through imidazolate linkers, in meeting this challenge and illustrate specific features that set ZIFs apart from other porous materials. The structures of ZIFs are characteristic of a variety of large, zeolite-like cages that are covalently connected with neighboring cages and fused in three-dimensional space.

Conceptual Advances from Werner Complexes to Metal-Organic Frameworks.

Alfred Werner's work on the geometric aspects of how ligands bind to metal ions at the end of the 19th century has given rise, in the molecular realm, to organometallic, bioinorganic, and cluster chemistries. By stitching together organic and inorganic units into crystalline porous metal-organic frameworks (MOFs), the connectivity, spatial arrangement, and geometry of those molecular complexes can now be fixed in space and become directly addressable. The fact that MOFs are porous provides additional space within which molecules can further be transformed and their chemistry controlled.

Identification of the strong Brønsted acid site in a metal-organic framework solid acid catalyst.

It remains difficult to understand the surface of solid acid catalysts at the molecular level, despite their importance for industrial catalytic applications. A sulfated zirconium-based metal-organic framework, MOF-808-SO, was previously shown to be a strong solid Brønsted acid material. In this report, we probe the origin of its acidity through an array of spectroscopic, crystallographic and computational characterization techniques.

Secondary building units as the turning point in the development of the reticular chemistry of MOFs.

The secondary building unit (SBU) approach was a turning point in the discovery of permanently porous metal-organic frameworks (MOFs) and in launching the field of reticular chemistry. In contrast to the single-metal nodes known in coordination networks, the polynuclear nature of SBUs allows these structures to serve as rigid, directional, and stable building units in the design of robust crystalline materials with predetermined structures and properties. This concept has also enabled the development of MOFs with ultra-high porosity and structural complexity.

Practical water production from desert air.

Energy-efficient production of water from desert air has not been developed. A proof-of-concept device for harvesting water at low relative humidity was reported; however, it used external cooling and was not desert-tested. We report a laboratory-to-desert experiment where a prototype using up to 1.

Metal-Organic Frameworks for Water Harvesting from Air.

Water harvesting from air in passive, adsorption-based devices holds great potential for delivering drinking water to arid regions of the world. This technology requires adsorbents that can be tailored for a maximum working capacity, temperature response, and the relative pressure range in which reversible adsorption occurs. In this respect, metal-organic frameworks (MOFs) are promising, owing to their structural diversity and the precision of their functionalization for adjusting both pore size and hydrophilicity, thereby facilitating the rational design of their water-sorption characteristics.

Covalent Organic Frameworks-Organic Chemistry Beyond the Molecule.

The synthesis of organic molecules has at its core, purity, definitiveness of structure, and the ability to access specific atoms through chemical reactions. When considering extended organic structures, covalent organic frameworks (COFs) stand out as a true extension of molecular organic chemistry to the solid state, because these three fundamental attributes of molecular organic chemistry are preserved. The fact that COFs are porous provides confined space within which molecules can be further modified and controlled.

Spiers Memorial Lecture:. Progress and prospects of reticular chemistry.

Reticular chemistry, the linking of molecular building units by strong bonds to make crystalline, extended structures such as metal-organic frameworks (MOFs), zeolitic imidazolate frameworks (ZIFs), and covalent organic frameworks (COFs), is currently one of the most rapidly expanding fields of science. In this contribution, we outline the origins of the field; the key intellectual and practical contributions, which have led to this expansion; and the new directions reticular chemistry is taking that are changing the way we think about making new materials and the manner with which we incorporate chemical information within structures to reach additional levels of functionality. This progress is described in the larger context of chemistry and unexplored, yet important, aspects of this field are presented.

The Chemistry of CO Capture in an Amine-Functionalized Metal-Organic Framework under Dry and Humid Conditions.

The use of two primary alkylamine functionalities covalently tethered to the linkers of IRMOF-74-III results in a material that can uptake CO at low pressures through a chemisorption mechanism. In contrast to other primary amine-functionalized solid adsorbents that uptake CO primarily as ammonium carbamates, we observe using solid state NMR that the major chemisorption product for this material is carbamic acid. The equilibrium of reaction products also shifts to ammonium carbamate when water vapor is present; a new finding that has impact on control of the chemistry of CO capture in MOF materials and one that highlights the importance of geometric constraints and the mediating role of water within the pores of MOFs.

Formation, Structure, and Frequency-Doubling Effect of a Modification of Strontium Cyanurate (α-SCY).

The low-temperature modification of Sr(OCN) was prepared and assigned as α-SCY after the high-temperature phase (now called β-SCY) and its frequency-doubling properties were reported recently. The crystal structure of α-SCY was solved and refined by single-crystal X-ray diffraction. Both modifications of SCY crystallize in noncentrosymmetric space groups, with the low-temperature phase (α-SCY) adopting the lower symmetry structure (Cc).