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Bak Kappel posted an update 1 year, 3 months ago
The visible-light photoredox/[Co(III)] cocatalyzed dehydrogenative functionalization of cyclic and acyclic styryl derivatives with carboxylic acids is documented. The methodology enables the chemo- and regioselective allylic functionalization of styryl compounds, leading to allylic carboxylates (32 examples) under stoichiometric acceptorless conditions. Intermolecular as well as intramolecular variants are documented in high yields (up to 82%). A mechanistic rationale is also proposed on the basis of a combined experimental and spectroscopic investigation.Machine learning has recently emerged as an efficient and powerful alternative to density functional theory for studying heterogeneous catalysis. Machine learning methods rely on a geometrical representation of the chemical environment around the catalytic adsorption site based on physical or chemical descriptors. Here, we show that replacing the atomic number in geometrical representations with elemental groups and periods (GP) yields significant improvements in predicted adsorption energies on bimetallic alloy surfaces. Notably, the GP-based Labeled Site Crystal Graph representation reported here achieves mean absolute error (MAE) ∼0.05 eV (near chemical accuracy) in predicting hydrogen adsorption and MAE ∼0.10 eV for other strong binding adsorbates such as carbon, nitrogen, oxygen, and sulfur. We also show GP-based representations to be robust in predicting adsorption on surface facets, elements, and alloys that are not included in the initial training set. This reliability makes GP-based representations an ideal basis for high-throughput approaches and materials discovery based on active learning techniques, which often involve limited training sets.(S)-carvedilol (S-CAR) is the dominant pharmacodynamic conformation of carvedilol, but its further development for extended-release formulation is restricted by its poor solubility. This study aimed to prepare and screen S-CAR salts that could be used to improve solubility and allow extended release. Five salts of S-CAR with well-known acid counterions (i.e., phosphate, hydrochloride, sulfate, fumarate, and tartrate) were produced using similar processes. However, these salts were obtained with water contents of 1.60-12.28%, and their physicochemical properties differed. The melting points of phosphate, hydrochloride, and tartrate were 1.1-1.5 times higher than that of the free base. The solubility of S-CAR salts was promoted to approximately 3-32 times higher than that of the free base at pH 5.0-8.0. Typical pH-dependent solubilities were evidently observed in S-CAR salts, but considerable differences in solubility properties among these salts were observed. S-CAR phosphate and hydrochloride possessed high melting points, considerable solubility, and excellent chemical and crystallographic stabilities. Accordingly, S-CAR phosphate and hydrochloride were chosen for further pharmacokinetic experiments and pharmaceutical study. S-CAR phosphate and hydrochloride extended-release capsules were prepared using HPMC K15 as the matrix and presented extended release in in vitro and in vivo evaluations. Results implied that water molecules in the hydrated salt were a potential threat to the achievement of crystal stability and thermostability. S-CAR phosphate and hydrochloride are suitable for further development of the extended-release formulation.A striking dependence on the method of workup has been found for annulation of benzonitriles ArC≡N to N-methyl 2-toluamide (1), facilitated by n-BuLi (2 equiv) quenching the reaction by a slow addition of water produced the expected 1-isoquinolones 2; by contrast, slow pouring of the reaction mixture into water afforded the cyclic aminals 5 (retaining the NMe group of the original toluamide). The mechanism of the two processes is discussed in terms of the actual H+ concentration in the workup. Both 2 and 5 were then converted into the corresponding 1-chloroisoquinolines 3, coupling of which, mediated by (Ph3P)2NiCl2/Zn, afforded bis-isoquinolines 4.A dominating F···π*aromatic interaction is found to govern the benzaldehyde···tetrafluoromethane complex, as revealed by this rotational spectroscopic investigation. Secondary F···π*-C=O- and C σ*CF4···πaromatic interactions also contribute to the stability of the observed isomer. Narrow splittings have been observed in the rotational spectrum originating from a 3-fold internal rotation of CF4 above the aromatic moiety, and a corresponding V3 barrier was determined to be 1.572(14) kJ mol-1. This is the first rotational spectroscopic evidence in the literature implying that the aromatic π* antibonding orbital can be activated not only by electron-withdrawing substituents but also by complexation partners containing atoms with high electronegativity, like CF4. The results emphasize the partner molecules’ role to modulate the π electron structure and show a change in the orbital character (π or π*) when participating in the formation of noncovalent interactions.Hydrostatically pressurized spectroscopic and lifetime decay analyses of optically active perylene bisimides were demonstrated in the pressure range of 0.1-320 MPa to show a π-stacked aggregation. The hydrostatic pressure-induced excitation and circular dichroism spectral changes of the fluorescence perylene dye enabled us to differentiate the slight pressure-sensitive aggregates. This work will lead to a new strategy for creating a pressure-responsive supramolecular polymerization material.Proteins undergo changes in their partial volumes in numerous biological processes such as enzymatic catalysis, unfolding-refolding, and ligand binding. FIIN-2 nmr The change in the protein volume upon ligand binding-a parameter termed the protein-ligand binding volume-can be extensively studied by high-pressure NMR spectroscopy. In this study, we developed a method to determine the protein-ligand binding volume from a single two-dimensional (2D) 1H-15N heteronuclear single quantum coherence (HSQC) spectrum at different pressures, if the exchange between ligand-free and ligand-bound states of a protein is slow in the NMR time-scale. This approach required a significantly lower amount of protein and NMR time to determine the protein-ligand binding volume of two carbonic anhydrase isozymes upon binding their ligands. The proposed method can be used in other protein-ligand systems and expand the knowledge about protein volume changes upon small-molecule binding.