Bioinspired Metal-Organic Framework Catalysts for Selective Methane Oxidation to Methanol.

Particulate methane monooxygenase (pMMO) is an enzyme that oxidizes methane to methanol with high activity and selectivity. Limited success has been achieved in incorporating biologically relevant ligands for the formation of such active site in a synthetic system. Here, we report the design and synthesis of metal-organic framework (MOF) catalysts inspired by pMMO for selective methane oxidation to methanol.

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.

New Metal-Organic Frameworks for Chemical Fixation of CO.

A novel series of two zirconium- and one indium-based metal-organic frameworks (MOFs), namely, MOF-892, MOF-893, and MOF-894, constructed from the hexatopic linker, 1',2',3',4',5',6'-hexakis(4-carboxyphenyl)benzene, were synthesized and fully characterized. MOF-892 and MOF-893 are two new exemplars of materials with topologies previously unseen in the important family of zirconium MOFs. MOF-892, MOF-893, and MOF-894 exhibit efficient heterogeneous catalytic activity for the cycloaddition of CO, resulting in a cyclic organic carbonate formation with high conversion, selectivity, and yield under mild conditions (1 atm CO, 80 °C, and solvent-free).

A Synthetic Route for Crystals of Woven Structures, Uniform Nanocrystals, and Thin Films of Imine Covalent Organic Frameworks.

Developing synthetic methodology to crystallize extended covalent structures has been an important pursuit of reticular chemistry. Here, we report a homogeneous synthetic route for imine covalent organic frameworks (COFs) where crystallites emerge from clear solutions without forming amorphous polyimine precipitates. The key feature of this route is the utilization of tert-butyloxycarbonyl group protected amine building blocks, which are deprotected in situ and gradually nucleate the crystalline framework.

Calcium l-Lactate Frameworks as Naturally Degradable Carriers for Pesticides.

Two porous, chiral metal-organic frameworks (MOFs), Ca(l-lactate)(acetate)(CHOH)(HO) (MOF-1201) and Ca(l-lactate)(acetate)(HO) (MOF-1203), are constructed from Ca ions and l-lactate [CHCH(OH)COO], where Ca ions are bridged by the carboxylate and hydroxyl groups of lactate and the carboxylate group of acetate to give a three-dimensional arrangement of Ca(-COO, -OH) polyhedra supporting one-dimensional pores with apertures and internal diameters of 7.8 and 9.6 Å (MOF-1201) and 4.

Principles of Designing Extra-Large Pore Openings and Cages in Zeolitic Imidazolate Frameworks.

We report three design principles for obtaining extra-large pore openings and cages in the metal-organic analogues of inorganic zeolites, zeolitic imidazolate frameworks (ZIFs). Accordingly, we prepared a series of 15 ZIFs, members of which have the largest pore opening (22.5 Å) and the largest cage size (45.

Plasmon-Enhanced Photocatalytic CO(2) Conversion within Metal-Organic Frameworks under Visible Light.

Materials development for artificial photosynthesis, in particular, CO reduction, has been under extensive efforts, ranging from inorganic semiconductors to molecular complexes. In this report, we demonstrate a metal-organic framework (MOF)-coated nanoparticle photocatalyst with enhanced CO reduction activity and stability, which stems from having two different functional units for activity enhancement and catalytic stability combined together as a single construct. Covalently attaching a CO-to-CO conversion photocatalyst Re(CO)(BPYDC)Cl, BPYDC = 2,2'-bipyridine-5,5'-dicarboxylate, to a zirconium MOF, UiO-67 (Re-MOF), prevents dimerization leading to deactivation.

Two Principles of Reticular Chemistry Uncovered in a Metal-Organic Framework of Heterotritopic Linkers and Infinite Secondary Building Units.

Structural diversity of metal-organic frameworks (MOFs) has been largely limited to linkers with at most two different types of coordinating groups. MOFs constructed from linkers with three or more nonidentical coordinating groups have not been explored. Here, we report a robust and porous crystalline MOF, Zn3(PBSP)2 or MOF-910, constructed from a novel linker PBSP (phenylyne-1-benzoate, 3-benzosemiquinonate, 5-oxidopyridine) bearing three distinct types of coordinative functionality.

Three-Dimensional Metal-Catecholate Frameworks and Their Ultrahigh Proton Conductivity.

A series of three-dimensional (3D) extended metal catecholates (M-CATs) was synthesized by combining the appropriate metal salt and the hexatopic catecholate linker, H6THO (THO(6-) = triphenylene-2,3,6,7,10,11-hexakis(olate)) to give Fe(THO)·Fe(SO4) (DMA)3, Fe-CAT-5, Ti(THO)·(DMA)2, Ti-CAT-5, and V(THO)·(DMA)2, V-CAT-5 (where DMA = dimethylammonium). Their structures are based on the srs topology and are either a 2-fold interpenetrated (Fe-CAT-5 and Ti-CAT-5) or noninterpenetrated (V-CAT-5) porous anionic framework. These examples are among the first catecholate-based 3D frameworks.

L-Aspartate links for stable sodium metal-organic frameworks.

Metal-organic frameworks (MOFs) based purely on sodium are rare, typically due to large numbers of coordinating solvent ligands. We designed a tetratopic aspartate-based linker with flexible carboxylate groups to enhance framework stability. We report two new air-stable sodium MOFs, MOF-705 and MOF-706, comprising 2D sodium oxide sheets.

Definitive molecular level characterization of defects in UiO-66 crystals.

The identification and characterization of defects, on the molecular level, in metal-organic frameworks (MOFs) remain a challenge. With the extensive use of single-crystal X-ray diffraction (SXRD), the missing linker defects in the zirconium-based MOF UiO-66, Zr6 O4 (OH)4 (C8 H4 O4 )6 , have been identified as water molecules coordinated directly to the zirconium centers. Charge balancing is achieved by hydroxide anions, which are hydrogen bonded within the pores of the framework.

Electric field gradient focusing using a variable width polyaniline electrode.

A new approach for electric field gradient focusing (EFGF) based on the use of a variable-width polyaniline (PANI) electrode is demonstrated. The electrode was created by patterning a PANI nanofibre film using a 635-nm laser and a computer-controlled XY stage. The electrode consisted of 16 segments of varying width, ranging from 200 to 5000 μm in 320 μm increments, with the resistance changing approximately 20-fold from 3881 to 198 kΩ at each extreme, respectively.