Controlled grafting of dialkylphosphonate-based ionic liquids on γ-alumina: design of hybrid materials with high potential for CO2 separation applications.

In this work we provide a detailed study on grafting reactions of various dialkylphosphonate-based ILs. Special attention has been devoted to a comprehensive investigation on how the nature of the anion and the organic spacer composition (hydrophilic or hydrophobic groups) could impact the grafting densities and bonding modes of phosphonate-based ILs anchored to γ-alumina (γ-Al2O3) powders. For the first time, the bonding of phosphonate-based ILs with only surface hexacoordinated aluminum nuclei was established using both solid-state 31P-27Al D-HMQC and 31P NMR experiments. It has been demonstrated that the grafting of dialkylphosphonate-based ILs is competing with a hydrolysis and/or precipitation process which could be attractively hindered by changing the anion nature: bis(trifluoromethane)sulfonylimide anion instead of bromide. In additon, independently of the chosen spacer, similar reaction conditions led to equivalent grafting densities with different bonding mode configurations. The CO2 physisorption analysis on both pure ILs and grafted ILs on alumina powders confirmed that the initial sorption properties of ILs do not change upon grafting, thus confirming the attractive potential of as-grafted ILs for the preparation of hybrid materials in a form of selective adsorbers or membranes for CO2 separation applications.

Highly crystalline MOF-based materials grown on electrospun nanofibers.

Supported Metal Organic Frameworks (MOFs) with a high specific surface area are of great interest for applications in gas storage, separation, sensing, and catalysis. In the present work we report the synthesis of a novel composite architecture of MOF materials supported on a flexible mat of electrospun nanofibers. The system, based on three-dimensional interwoven nanofibers, was designed by using a low-cost and scalable multistep synthesis protocol involving a combination of electrospinning and low-temperature atomic layer deposition of oxide materials, and their subsequent solvothermal conversion under either conventional or microwave-assisted heating. This highly versatile approach allows the production of different types of supported MOF crystals with controlled sizes, morphology, orientation and high accessibility.

Restriction endonucleases that resemble a component of the bacterial DNA repair machinery.

It has long been known that most Type II restriction endonucleases share a conserved core fold and similar active-sites. The same core folding motif is also present in the MutH protein, a component of the bacterial DNA mismatch repair machinery. In contrast to most Type II restriction endonucleases, which assemble into functional dimers and catalyze double-strand breaks, MutH is a monomer and nicks hemimethylated DNA. Recent biochemical and crystallographic studies demonstrate that the restriction enzymes BcnI and MvaI share many additional features with MutH-like proteins, but not with most other restriction endonucleases. The structurally similar monomers all recognize approximately symmetric target sequences asymmetrically. Differential sensitivities to slight substrate asymmetries, which could be altered by protein engineering, determine whether the enzymes catalyze only single-strand nicks or double-strand breaks.