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Molecular interactions with both oxides and metals are essential for heterogenous catalysis, leading to remarkable synergistic impacts on activity and selectivity. Here, we show that the direct link between the two phases (and not merely being together) is required to selectively hydrogenate CO 2 to methanol on catalysts containing Cu and ZrO 2 . Materials consisting of isolated Cu particles or atomically dispersed Cu–O–Zr sites only catalyze the reverse water-gas shift reaction. In contrast, a metal organic framework structure (UiO-66) with Cu nanoparticles occupying missing-linker defects maximizes the fraction of metallic Cu interfaced to ZrO 2 nodes leading to a material with high adsorption capacity for CO 2 and high activity and selectivity for low-temperature methanol synthesis. Molecular interactions with both oxides and metals are essential for heterogenous catalysis, leading to remarkable impacts on activity. Here the authors show that a direct link between Cu and ZrO2 in a metal organic framework is required to hydrogenate CO2 to methanol.

A porous metal–organic framework with ultrawide channels and excellent chemical stability is now shown to be highly efficacious for the catalytic decomposition of chemical warfare agents containing phosphate ester bonds. Chemical warfare agents containing phosphonate ester bonds are among the most toxic chemicals known to mankind 1 . Recent global military events, such as the conflict and disarmament in Syria 2 , have brought into focus the need to find effective strategies for the rapid destruction of these banned chemicals. Solutions are needed for immediate personal protection (for example, the filtration and catalytic destruction of airborne versions of agents), bulk destruction of chemical weapon stockpiles, protection (via coating) of clothing, equipment and buildings, and containment of agent spills 3 . Solid heterogeneous materials such as modified activated carbon or metal oxides exhibit many desirable characteristics for the destruction of chemical warfare agents 4 , 5 , 6 . However, low sorptive capacities, low effective active site loadings, deactivation of the active site, slow degradation kinetics, and/or a lack of tailorability offer significant room for improvement in these materials. Here, we report a carefully chosen metal–organic framework (MOF) material featuring high porosity and exceptional chemical stability that is extraordinarily effective for the degradation of nerve agents and their simulants. Experimental and computational evidence points to Lewis-acidic Zr IV ions as the active sites and to their superb accessibility as a defining element of their efficacy.

The structures and the O-O and M-O bonding characters of a series of reported side-on (η2) 1:1 metal complexes of O2 are analyzed by using density functional theory calculations. Comparison of the calculated and experimental systems with respect to O-O bond distance, O-O stretching frequency, and O-O and M-O bond orders provides new insights into subtle influences relevant to O2 activation processes in biology and catalysis. The degree of charge transfer from the generally electron-rich metals to the dioxygen fragment is found to be variable, such that there are species well described as superoxides, others well described as peroxides, and several cases having intermediate character. Increased charge transfer to dioxygen takes place via overlap of the metal dxy orbital with the in-plane π* orbital of O2 and results in increased M-O bond orders and decreased O-O bond orders. Comparison of theory and experiment over the full range of compounds studied suggests that reevaluation of the O-O bond lengths determined from certain x-ray crystal structures is warranted; in one instance, an x-ray crystal structure redetermination was performed at low temperature, confirming the theoretical prediction. Librational motion of the coordinated O2 is identified as a basis for significant underestimation of the O-O distance at high temperature.

Cross-coupling reactions enable rapid, convergent synthesis of diverse molecules and provide the foundation for modern chemical synthesis. The most widely used methods employ sp 2 -hybridized coupling partners, such as aryl halides or related pre-functionalized substrates. Here, we demonstrate copper-catalysed oxidative cross-coupling of benzylic C–H bonds with alcohols to afford benzyl ethers, enabled by a redox buffering strategy that maintains the activity of the copper catalyst throughout the reaction. The reactions employ the C–H substrate as the limiting reagent and exhibit broad scope with respect to both coupling partners. This approach to direct site-selective functionalization of C( sp 3 )–H bonds provides the basis for efficient three-dimensional diversification of organic molecules and should find widespread utility in organic synthesis, particularly for medicinal chemistry applications. The cross-coupling of C–H bonds with alcohols is a highly efficient route to ethers. Here the authors report such an oxidative coupling, by use of a radical relay to both promote hydrogen atom transfer and activate the copper catalyst for cross-coupling.

A method is developed for the prediction of mass spectral ion counts of drug-like molecules using in silico calculated chemometric data. Various chemometric data, including polar and molecular surface areas, aqueous solvation free energies, and gas-phase and aqueous proton affinities were computed, and a statistically significant relationship between measured mass spectral ion counts and the combination of aqueous proton affinity and total molecular surface area was identified. In particular, through multilinear regression of ion counts on predicted chemometric data, we find that log 10 (MS ion counts) = –4.824 + c 1 •PA + c 2 •SA, where PA is the aqueous proton affinity of the molecule computed at the SMD(aq)/M06-L/MIDI!//M06-L/MIDI! level of electronic structure theory, SA is the total surface area of the molecule in its conjugate base form, and c 1 and c 2 have values of –3.912 × 10 –2 mol kcal –1 and 3.682 × 10 –3 Å –2 . On a 66-molecule training set, this regression exhibits a multiple R value of 0.791 with p values for the intercept, c 1 , and c 2 of 1.4 × 10 –3 , 4.3 × 10 –10 , and 2.5 × 10 –6 , respectively. Application of this regression to an 11-molecule test set provides a good correlation of prediction with experiment ( R = 0.905) albeit with a systematic underestimation of about 0.2 log units. This method may prove useful for semiquantitative analysis of drug metabolites for which MS response factors or authentic standards are not readily available. Graphical Abstract ᅟ

AbstractWe present an extension of the AMOEBA force field to several common organic heterocycles, namely pyridine, pyrazine, pyrimidine, pyridazine, the three unique triazines, and the two unique tetrazines. Atomic multipoles for newly defined atom types were obtained from quantum chemical calculations on the isolated molecules. Atomic polarizability parameters are maintained at their standard AMOEBA values for corresponding atomic classes while standard van der Waals parameters are rescaled to reproduce CCSD(T) intermolecular interaction energies of selected dimer structures. In order to improve vibrational frequencies that are important both spectroscopically and for flexible dynamics, parameters for covalent terms, i.e., bond-stretching, angle-bending, and stretch-bend terms, were optimized and added to the existing AMOEBA force field. We validate our force field through comparison of molecular structural, vibrational, electrostatic, and energetic properties—including intermolecular interaction energies—to reliable quantum chemical data for the various systems of interest.

We present eight new parameterizations of the SM5.42R solvation model: in particular we present parameterizations for HF/MIDI!, HF/6-31G*, HF/6-31+G*, HF/cc-pVDZ, AM1, PM3, BPW91/MIDI!, and B3LYP/MIDI!. Two of the new cases are parameterized using the reaction-field operator presented previously, and six of the new cases are parameterized with a simplified reaction-field operator; results obtained by the two methods are compared for selected examples. For a training set of 2135 data for 275 neutral solutes containing H, C, N, O, F, S, P, Cl, Br, and I in 91 solvents (water and 90 nonaqueous solvents), seven of the eight new parameterizations give mean unsigned errors in the range 0.43–0.46 kcal/mol, and the eighth – for a basis set containing diffuse functions – gives a mean unsigned error of 0.53 kcal/mol. The mean unsigned error for 49 ionic solutes (containing the same elements) in water is 3.5–3.9 kcal/mol for the Hartree–Fock, Becke–Perdew–Wang-1991 and Becke three-parameter Lee–Yang–Parr cases and 4.1 and 4.0 kcal/mol for parameterized model 3 and Austin model 1, respectively. The methods are tested for sensitivity of solvation free energies to geometry and for predicting partition coefficients of carbonates, which were not included in the training set.

We applied the solvation models SM8, SM8AD, and SMD in combination with the Minnesota M06-2X density functional to predict vacuum-water transfer free energies (Task 1) and tautomeric ratios in aqueous solution (Task 2) for the SAMPL2 test set. The bulk-electrostatic contribution to the free energy of solvation is treated as follows: SM8 employs the generalized Born model with the Coulomb field approximation, SM8AD employs the generalized Born approximation with asymmetric descreening, and SMD solves the nonhomogeneous Poisson equation. The non-bulk-electrostatic contribution arising from short-range interactions between the solute and solvent molecules in the first solvation shell is treated as a sum of terms that are products of geometry-dependent atomic surface tensions and solvent-accessible surface areas of the individual atoms of the solute. On average, three models tested in the present work perform similarly. In particular, we achieved mean unsigned errors of 1.3 (SM8), 2.0 (SM8AD), and 2.6 kcal/mol (SMD) for the aqueous free energies of 30 out of 31 compounds with known reference data involved in Task 1 and mean unsigned errors of 2.7 (SM8), 1.8 (SM8AD), and 2.4 kcal/mol (SMD) in the free energy differences (tautomeric ratios) for 21 tautomeric pairs in aqueous solution involved in Task 2.