Adsorptive-dissolution of O into the potential nanospace of a densely fluorinated metal-organic framework.

Nanoporous solids, including metal-organic frameworks (MOFs), have long been known to capture small molecules by adsorption on their pore surfaces. Liquids are also known to accommodate small molecules by dissolution. These two processes have been recognized as fundamentally distinct phenomena because of the different nature of the medium-solids and liquids.

Development of a Ru-porphyrin-based supramolecular framework catalyst for styrene epoxidation.

A new microporous supramolecular-framework Ru(II)-porphyrin catalyst containing non-covalent interactions between pyrenylphenyl moieties at the -position of the porphyrin ring is synthesised and structurally characterised. This recyclable catalyst expedites styrene epoxidation more efficiently than homogeneous Ru-porphyrin catalytic systems.

An n-type semiconducting diazaporphyrin-based hydrogen-bonded organic framework.

Significant effort has been devoted to the development of materials that combine high electrical conductivity and permanent porosity. This paper discloses a diazaporphyrin-based hydrogen-bonded organic framework (HOF) with porosity and n-type semiconductivity. A 5,15-diazaporphyrin Ni(ii) complex with carboxyphenyl groups at the positions afforded a HOF due to hydrogen-bonding interactions between the carboxy groups and -nitrogen atoms.

A magnesium phosphonate metal-organic framework showing excellent performance for lead(II) sensing and removal from aqueous solutions.

A hydrogen-bonded three-dimensional porous metal-organic framework [Mg(HPCD)(HO)]·2HO (denoted as Mg-MOF·2HO; HPCD = 9-(2-(ethoxy(hydroxy)phosphonyl)ethyl)-9-carbazole-3,6-dicarboxylic acid) was synthesized by the reactions of HPCD and Mg(II) under solvothermal conditions. The free carboxylate group was maintained in the pore surface by adjusting the acidic reaction conditions. The highly stable Mg-MOF exhibits excellent performance for lead(II) sensing and removal from aqueous solutions.

Three-Dimensional Visualization of Adsorption Distribution in a Single Crystalline Particle of a Metal-Organic Framework.

Many unique adsorption properties of metal-organic frameworks (MOFs) have been revealed by diffraction crystallography, visualizing their vacant and guest-loaded crystal structures at the molecular scale. However, it has been challenging to see the spatial distribution of the adsorption behaviors throughout a single MOF particle in a transient equilibrium state. Here, we report three-dimensional (3D) visualization of molecular adsorption behaviors in a single crystalline particle of a MOF by X-ray absorption fine structure spectroscopy combined with computed tomography for the first time.

Engineering Interface Defects and Interdiffusion at the Degenerate Conductive InO/AlO Interface for Stable Electrodes in a Saline Solution.

A low-temperature AlO deposition process provides a simplified method to form a conductive two-dimensional electron gas (2DEG) at the metal oxide/AlO heterointerface. However, the impact of key factors of the interface defects and cation interdiffusion on the interface is still not well understood. Furthermore, there is still a blank space in terms of applications that go beyond the understanding of the interface's electrical conductivity.

Beyond the Conventional Limitation of Photocycloaddition Reaction in the Roomy Nanospace of a Metal-Organic Framework.

Topochemical reactions provide selective products based on the molecular position; however, they generally require molecules to be placed in strictly limited orientations and distances, making them less versatile. In this study, we found that by confining -4-styrylpyridine (4-spy) as a reactive substrate in a flexible metal-organic framework (MOF) nanospace, [2+2] cycloadducts can be selectively obtained, even when the distance between two C═C bonds of 4-spy in the crystal is 5.9 Å, which is much larger than the conventionally observed upper limit (4.

Covalent organic framework atropisomers with multiple gas-triggered structural flexibilities.

Covalent organic frameworks (COFs) are emerging crystalline porous polymers, showing great potential for applications but lacking gas-triggered flexibility. Atropisomerism was experimentally discovered in 1922 but has rarely been found in crystals with infinite framework structures. Here we report atropisomerism in COF single crystals.

Creation of single molecular conjugates of metal-organic cages and DNA.

Here we report the development of an equimolar conjugate of a metal-organic cage (MOC) and DNA (MOC-DNA). Several MOC-DNA conjugates were assembled into a programmed structure by coordinating with a template DNA having a complementary base sequence. Moreover, conjugation with the MOC drastically enhanced the permeability of DNA through the lipid bilayer, presenting great potential as a drug delivery system.

Delicate and Fast Photochemical Surface Modification of 2D Photoresponsive Organosilicon Metal-Organic Frameworks.

Photoresponsive arylsilanes have been fascinating molecules for decades because of their unique photophysical characteristics and surface chemistry. Here we report the synthesis and fabrication of a crystalline two-dimensional trisilyl metal-organic framework (TSiMOF) orderly installed with the classical photoresponsive hexamethyltrisilane groups on the surface. Irradiated by UV light under air in minutes the fluorescence of the TSiMOF is turned on simultaneously with an intriguing surface transformation from superhydrophobic to hydrophilic.

Topochemical [2 + 2] Cycloaddition in a Two-Dimensional Metal-Organic Framework via SCSC Transformation Impacts HalogenHalogen Interactions.

A photoactive two-dimensional metal-organic framework (2D MOF) [Zn(4-spy)(DCTP)] () [where 4-spy = 4-styrylpyridine and HDCTP = 2,5-dichloroterephthalic acid] undergoes photochemical [2 + 2] cycloaddition on UV irradiation to obtain three-dimensional (3D) MOF [Zn(-4-ppcb)(DCTP)] () [-4-ppcb = 1,3-bis(4'-pyridyl)-2,4-bis(phenyl)cyclobutane] in a single-crystal to single-crystal (SCSC) manner. This structural transformation leads to stronger halogenhalogen interaction that is well-corroborated by density functional theory (DFT) calculations.

Design of a MOF based on octa-nuclear zinc clusters realizing both thermal stability and structural flexibility.

An octa-nuclear zinc (Zn) cluster-based two-fold interpenetrated metal-organic framework (MOF) of [(CH)NH][ZnO(FDC)]·7DMF (denoted as Zn8-as; HFDC = 9-fluorene-2,7-dicarboxylic acid; DMF = ,-dimethylformamide) was synthesized by the reaction of a hard base of a curved dicarboxylate ligand (HFDC) with the borderline acid of Zn(II) under solvothermal conditions. Zn8-as shows significant crystal volume shrinkage upon heating, yielding a solvate-free framework of [(CH)NH][ZnO(FDC)] (Zn8-de). Zn8-de displays gated adsorption for CH and type-I adsorption for CO, attributed to the framework flexibility and the different interactions between the gas molecules and the host framework.

Stabilization of radical active species in a MOF nanospace to exploit unique reaction pathways.

We synthesized a metal-organic framework (MOF) using a ligand bearing haloalkoxy chains as a radical precursor. The radicals generated in the MOF upon photoirradiation were stable even at 250 K or under an O atmosphere, despite radicals generated from the ligand decomposing at 200 K; thus, the regular arrangement of radicals effectively stabilized them. Moreover, a unique photoproduct was obtained only in the MOF, indicating that the confinement effect in the nanospace enabled a specific reaction that did not occur in the bulk state.

Fabrication of a Kagomé-type MOF Membrane by Seeded Growth on Amino-functionalized Porous Al O Substrate.

In this study, we report an efficient fabrication method for the membrane of a metal-organic framework (MOF) (Kgm-OEt) which is one kind of kagomé-type MOF with a two-dimensional (2D) sheet structure having one-dimensional (1D) channels suitable for separation of H from other larger gases. The Kgm-OEt seed layer was created on an Al O substrate using layer-by-layer (LBL) growth, then a membrane was fabricated by secondary growth. The membrane on a 3-aminopropyltriethoxysilane (APTEs)-treated substrate obtained in this method was continuous and defect-free with the crystal orientation suitable for gas transportation, while the membrane grown on an unmodified substrate was loosely packed with unfavorable crystal orientation.

Triplet Carbene with Highly Enhanced Thermal Stability in the Nanospace of a Metal-Organic Framework.

Triplet carbenes (s) are of great interest due to their magnetic properties and reactivity, which descend from s' unique electronic state. However, the reactivity and stability of s are usually a trade-off, and it is difficult to achieve both at the same time. In this work, we were able to enhance the thermal stability of a species while maintaining its reactivity by confining them in the nanospace of a metal-organic framework (MOF).

An Open-shell, Luminescent, Two-Dimensional Coordination Polymer with a Honeycomb Lattice and Triangular Organic Radical.

The use of organic radicals as building blocks is an effective approach to the production of open-shell coordination polymers (CPs). Two-dimensional (2D) CPs with honeycomb spin-lattices have attracted attention because of the unique electronic structures and physical properties afforded by their structural topology. However, radical-based CPs with honeycomb spin-lattices tend to have low chemical stability or poor crystallinity, and thus novel systems with high crystallinity and persistence are in strong demand.

Modulation of Self-Assembly Enhances the Catalytic Activity of Iron Porphyrin for CO Reduction.

Electrochemical reduction of CO in aqueous media is an important reaction to produce value-added carbon products in an environmentally and economically friendly manner. Various molecule-based catalytic systems for the reaction have been reported thus far. The key features of state-of-the-art catalytic systems in this field can be summarized as follows: 1) an iron-porphyrin-based scaffold as a catalytic center, 2) a dinuclear active center for the efficient activation of a CO molecule, and 3) a hydrophobic channel for the accumulation of CO .

Trapping and Releasing of Oxygen in Liquid by Metal-Organic Framework with Light and Heat.

Nanoporous materials can adsorb small molecules into their nanospaces. However, the trapping of light gas molecules dissolved in solvents suffers from low concentration and poor adsorption affinity. Here, the reversible trapping and releasing of dissolved oxygen are shown through integrating photosensitization and chemical capturing abilities into a metal-organic framework (MOF), MOMF-1.

Molecular motion in the nanospace of MOFs upon gas adsorption investigated by in situ Raman spectroscopy.

Molecular motions taking place in the nanospace of metal-organic frameworks (MOFs) are an interesting research subject, although not yet fully investigated. In this work, we utilized in situ Raman spectroscopy in the ultralow-frequency region to investigate the libration motion (including the rotational motion of phenylene rings) of MOFs, in particular [Cu(bdc)(dabco)] (Cu-JAST-1), where bdc = 1,4-benzenedicarboxylate and dabco = 1,4-diazabicyclo[2.2.

Tuning Gate-Opening of a Flexible Metal-Organic Framework for Ternary Gas Sieving Separation.

In comparison with the fast development of binary mixture separations, ternary mixture separations are significantly more difficult and have rarely been realized by a single material. Herein, a new strategy of tuning the gate-opening pressure of flexible MOFs is developed to tackle such a challenge. As demonstrated by a flexible framework NTU-65, the gate-opening pressure of ethylene (C H ), acetylene (C H ), and carbon dioxide (CO ) can be regulated by temperature.

Direct observation of dimethyl sulfide trapped by MOF proving efficient removal of sulfur impurities.

Here, we report the adsorptive removal of trace amounts of dimethyl sulfide (DMS) using metal-organic frameworks (MOFs). Cu-based MOFs with open metal sites (OMSs), [Cu(btc)] (HKUST-1), where btc = 1,3,5-benzenetricarboxylate, and without OMSs, [Cu(bdc)(dabco)] (Cu-JAST-1), where bdc = 1,4-benzenedicarboxylate and dabco = 1,4-diazabicyclo[2.2.