Callahan Harper (beastpimple48)

The activation and catalytic conversion of CO2 is a current topic relating to molecular chemistry and materials science alike. As a transdisciplinary field of research, surface organometallic chemistry (SOMC) might be applicable to perform synergistically, thus striking a new path in sustainable chemistry. Both ceric and cerous rare-earth-metal pyrazolates, which were recently shown to reversibly insert CO2 and to promote the catalytic cycloaddition of epoxides and carbon dioxide, were grafted onto large-pore mesoporous silica SBA-15500, thermally pretreated at 500 °C. The obtained hybrid materials [Ce(Me2pz)4]2@SBA-15500, Ce(Me2pz)4(thf)@SBA-15500, Ce4(Me2pz)12@SBA-15500, and [Ce(Me2pz)3(thf)]2@SBA-15500 (Me2pz = 3,5-dimethylpyrazolato) were characterized by DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy), solid-state 1H/13C NMR spectroscopy, elemental analysis, ICP/OES, and N2 physisorption. The lanthanum(III)-based material [La(Me2pz)3(thf)]2@SBA-15500 was synthesized for better assessment of the cerous materials being highly sensitive to oxidation. To mimic ceric surface species, Ce[OSi(OtBu)3]3Cl was treated with 1 equiv of K(Me2pz), generating the mixed pyrazolyl/siloxy complex KCe[OSi(OtBu)3]4(Me2pz) featuring a cerium(IV)-bonded terminal pyrazolato ligand. All hybrid materials show efficient and reversible carbon dioxide uptake of maximum 20 wt % in the solid state. When combined with tetra-n-butylammonium bromide (TBAB), the hybrid materials catalyze the cycloaddition of CO2 and epoxides, displaying good conversion of various epoxides and reusability.SF5Phe, para-pentafluorosulfanyl phenylalanine, is an unnatural amino acid with extreme physicochemical properties, which is stable in physiological conditions. Here we present newly developed aminoacyl-tRNA synthetases that enable genetic encoding of SF5Phe for site-specific incorporation into proteins in high yields. Owing to the SF5 moiety's dichotomy of strong polarity and high hydrophobicity, the unnatural amino acid forms specific and strong interactions in proteins. The potential of SF5Phe in protein research is illustrated by (i) increasing the binding affinity of a consensus pentapeptide motif toward the β subunit of Escherichia coli DNA polymerase III holoenzyme by mutation of a phenylalanine to a SF5Phe residue, (ii) site-specifically adhering β-cyclodextrin to the surface of ubiquitin, and (iii) selective detection of 19F-19F nuclear Overhauser effects in the Escherichia coli peptidyl-prolyl cis/trans-isomerase B following mutation of two phenylalanine residues in the core of the protein to SF5Phe. With increasing use of the SF5 moiety in pharmaceutical chemistry, this general method of functionalizing proteins with SF5 groups opens unique opportunities for structural biology and in vivo studies.T helper 17 (Th17) cells, an important subset of CD4+ T cells, help to eliminate extracellular infectious pathogens that have invaded our tissues. Despite the critical roles of Th17 cells in immunity, how the immune system regulates the production and maintenance of this cell type remains poorly understood. In particular, the plasticity of these cells or their dynamic ability to trans-differentiate into other CD4+ T cell subsets remains mostly uncharacterized. Here, we report a synthetic immunology approach using a photoactivatable immune modulator (PIM) to increase Th17 cell differentiation on demand with spatial and temporal precision to help elucidate this important and dynamic process. In this chemical strategy, we developed a latent agonist that upon photochemical activation releases a small-molecule ligand that targets the aryl hydrocarbon receptor (AhR) and ultimately induces Th17 cell differentiation. We used this chemical tool to control AhR activation with spatiotemporal precision within cells and to modulate Th17 cell differentiation on demand using UV light illumination. We envision