Seeing the light: Two highly porous metal–organic frameworks (MOFs) were transformed using UV light to produce MOFs with hydroxy and catechol groups through an unusual postsynthetic deprotection reaction (see scheme).
Perfluoropentane (PFP) gas filled biodegradable iron-doped silica nanoshells have been demonstrated as long-lived ultrasound contrast agents. Nanoshells are synthesized by a sol-gel process with tetramethyl orthosilicate (TMOS) and iron ethoxide. Substituting a fraction of the TMOS with R-substituted trialkoxysilanes produces ultrathin nanoshells with varying shell thicknesses and morphologies composed of fused nanoflakes. The ultrathin nanoshells had continuous ultrasound Doppler imaging lifetimes exceeding 3 hours, were twice as bright using contrast specific imaging, and had decreased pressure thresholds compared to control nanoshells synthesized with just TMOS. Transmission electron microscopy (TEM) showed that the R-group substituted trialkoxysilanes could reduce the mechanically critical nanoshell layer to 1.4 nm. These ultrathin nanoshells have the mechanical behavior of weakly linked nanoflakes but the chemical stability of silica. The synthesis can be adapted for general fabrication of three-dimensional nanostructures composed of nanoflakes, which have thicknesses from 1.4–3.8 nm and diameters from 2–23 nm.
A greige (non-bleached) cotton lint was used to fabricate non-woven fabrics on a Fleissner MiniJet, using different water pressures for the fiber entanglements. The greige cotton and its hydroentangled non-woven fabrics were primarily tested for their hexane extracts (waxes) and water-soluble (sugars) contents using the AATCC TM97 Standard Extraction Test. Tests have shown that a water pressure of 125 Bar or higher almost totally removed the greige cotton’s inherent hydrophobic waxes and water-soluble sugars. This discovery is a significant milestone in the development of greige cotton-based non-wovens because it could change the greige cotton’s native hydrophobic character into a desirable hydrophilic character for many end-uses. In fact, the AATCC Test Method 79-2007 has confirmed that the greige cotton non-wovens fabricated with high water pressure of 125 Bar are absorbent, as indicated by the 1-second time or less it took for the water drop to completely diffuse onto the fabric surface.
A postsynthetic modification (PSM) scheme for metal-organic frameworks (MOFs) has been developed using a tetrazine-based "Click" reaction. It was found that the efficacy of this modification procedure was dependent on the MOF topology and, in the case of an isoreticular MOF (IRMOF) system, required the formation of a mixed-ligand IRMOF with a suitable ratio of 1,4-benzenedicarboxylate (BDC) and an olefin-tagged BDC derivative. On the basis of the versatile use of tetrazine "Click" chemistry in bioconjugate chemistry, we expect that this scheme will prove to be a useful reaction for preparing functionalized materials, including MOFs.
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