Fluorescent composite hydrogels of metal-organic frameworks and functionalized graphene oxide

GO MOFs! Azobenzoic acid functionalized graphene (A-GO) can act as a structure-directing template that influences hydrogel formation together with metal-organic frameworks (MOFs). Zn(2+) MOFs of pyridine derivatives work as framework linkers between the A-GO sheets (MOF-A-GO, see figure). MOF-A-GO exhibits a strong fluorescence enhancement upon gel formation. In addition, MOF-A-GO selectively recognizes trinitrotoluene.     

Selective Host–Guest Interaction between Metal Ions and Metal–Organic Frameworks Using Dynamic Nuclear Polarization Enhanced Solid‐State NMR Spectroscopy

The host–guest interaction between metal ions (Pt²⁺ and Cu²⁺) and a zirconium metal–organic framework (UiO‐66‐NH₂) was explored using dynamic nuclear polarization‐enhanced ¹⁵N{¹H} CPMAS NMR spectroscopy supported by X‐ray absorption spectroscopy and density functional calculations. The combined experimental results conclude that each Pt²⁺ coordinates with two NH₂ groups from the MOF and two Cl^? from the metal precursor, whereas Cu²⁺ do not form chemical bonds with the NH₂ groups of the MOF framework. Density functional calculations reveal that Pt²⁺ prefers a square‐planar structure with the four ligands and resides in the octahedral cage of the MOF in either cis or trans configurations.     

Transport into metal-organic frameworks from solution is not purely diffusive

Chemistry in motion: a combination of confocal microscopy and reaction-diffusion modeling provided a powerful toolkit with which solution transport into metal-organic framework crystals was studied. Commonly used pure diffusion models are insufficient to describe this process and, instead, it is necessary to account for the interactions of the guest molecules and the MOF scaffold.     

Matrix‐Free DNP‐Enhanced NMR Spectroscopy of Liposomes Using a Lipid‐Anchored Biradical

Magic‐angle spinning dynamic nuclear polarization (MAS‐DNP) has been proven to be a powerful technique to enhance the sensitivity of solid‐state NMR (SSNMR) in a wide range of systems. Here, we show that DNP can be used to polarize lipids using a lipid‐anchored polarizing agent. More specifically, we introduce a C16‐functionalized biradical, which allows localization of the polarizing agents in the lipid bilayer and DNP experiments to be performed in the absence of excess cryo‐protectant molecules (glycerol, dimethyl sulfoxide, etc.). This constitutes another original example of the matrix‐free DNP approach that we recently introduced.     

Assembly of the first fullerene-type metal-organic frameworks using a planar five-fold coordination node

Pump up the volume: Slow crystallization of Na[C(5) (CN)(5) ], the unsolvated sodium salt of pentacyanocyclopentadienide, gives the first example of an anionic coordination network based on metal-fullerene units. The structure of this network is closely related to a type?I gas clathrate in which around 66?% of the unit cell volume is occupied by solvent molecules.     

A family of chiral metal-organic frameworks

Chiral metal–organic frameworks with a three‐dimensional network structure and wide‐open pores (>30 Å) were obtained by using chiral trifunctional linkers and multinuclear zinc clusters. The linkers, H₃ChirBTB‐n, consist of a 4,4′,4′′‐benzene‐1,3,5‐triyltribenzoate (BTB) backbone decorated with chiral oxazolidinone substituents. The size and polarity of these substituents determines the network topology formed under solvothermal synthesis conditions. The resulting chiral MOFs adsorb even large molecules from solution. Moreover, they are highly active Lewis acid catalysts in the Mukaiyama aldol reaction. Due to their chiral functionalization, they show significant levels of enantioselectivity, thereby proving the validity of the modular design concept employed.     

Functional mixed metal-organic frameworks with metalloligands

Immobilization of functional sites within metal-organic frameworks (MOFs) is very important for their ability to recognize small molecules and thus for their functional properties. The metalloligand approach has enabled us to rationally immobilize a variety of different functional sites such as open metal sites, catalytic active metal sites, photoactive metal sites, chiral pore environments, and pores of tunable sizes and curvatures into mixed metal-organic frameworks (M'MOFs). In this Minireview, we highlight some important functional M'MOFs with metalloligands for gas storage and separation, enantioselective separation, heterogeneous asymmetric catalysis, sensing, and as photoactive and nanoscale drug delivery and biomedical imaging materials.