This work reports on a comprehensive analysis of the predictive capacity and underlying physicochemical trends provided by d-band based electronic structure features as applied to single-atom alloys (SAAs). Taking CO adsorption energies at kink sites as a model framework, SAA adsorption trends are examined across a range of substrates with vastly differing intrinsic CO adsorption trends. Through this approach, it is demonstrated that SAA adsorption properties can be highly transferable, often displaying atom-like behavior independent of the host substrate, particularly in groups 6 through 12 of the periodic table. The predictability of such SAA behavior is found, however, to be highly qualitative for single d-band based electronic structure features. Nevertheless, it is shown that predictive capacity can be greatly improved through the creation of a feature space comprised of as few as 8 electronic structure features. Intriguingly, following the framework of Hammer and Nørskov, the machine learning accuracy of d-band based electronic structure features is shown to be sensitive to the atomic configuration diversity present in the training ensemble with model accuracy systematically improving through restrictions in the configurational space. More directly, it is shown that elements to the far left of the transition metal block such as Zr and Hf may exhibit CO binding properties comparable to Cu in the CO 2 reduction reaction. However, impurities from groups 6−10 are demonstrated to overbind in a highly transferable manner in line with established pure substrate trends and are likely to act as unwanted posing species concerning CO and the overall CO 2 reduction reaction. The results of this work broadly lay out the predictive capabilities of d-band features as applied to SAAs, as well as their propensity for exhibiting transferable binding properties among d-band substrates.

A light-driven pinacol coupling protocol without any metals, but with N2H4 as a clean non-metallic hydrogen-atom-transfer (HAT) reductant was described.

Metal binding affinities play a vital role in medicinal, biological, and industrial applications. In particular, metal cation–amino acid (AA) interactions contribute to protein stability such that analyzing analogous prototypical interactions is important. Here, we present a full description of the interactions of sodium cations (Na+) and six aliphatic amino acids (AA), where AA = glycine (Gly), alanine (Ala), homoalanine (hAla), valine (Val), leucine (Leu), and isoleucine (Ile). Experimentally, these interactions are evaluated using threshold collision-induced dissociation carried out in a guided ion beam tandem mass spectrometer, allowing for the determination of the kinetic-energy-dependent behavior of Na+–AA dissociation. Analysis of these dissociation cross sections, after accounting for multiple ion–molecule collisions, internal energy of reactant ions, and unimolecular decay rates, allows the determination of absolute Na+–AA bond dissociation energies (BDEs) in kJ/mol of Gly (164.0), Ala (166.9), hAla (167.9), Val (172.7), Leu (173.7), and Ile (174.6). These are favorably compared to quantum chemical calculations conducted at the B3LYP, B3P86, MP2­(full), B3LYP-GD3BJ, and M06-2X levels of theory. Our combination of structural and energetic analyses provides information regarding the specific factors responsible for Na+ interactions with amino acids. Specifically, we find that the BDEs increase linearly with increasing polarizability of the amino acid.

Cyclodextrin-derived metal−organic frameworks (MOFs) are remarkable not only because of their ability to absorb carbon dioxide strongly and reversibly but also because they can be readily obtained from inexpensive, renewable, and environmentally benign components. Despite the wealth of data on the carbon dioxide intake by CD-MOF-2, a representative of these MOFs, the nature and structural characteristics of its diverse adsorption sites, capable of binding CO 2 in the irreversible, reversible, and weak regimes, remain unclear. A comprehensive analysis of the results of the density functional theory modeling performed in this work in conjunction with experimental data shows that the hydroxyl counterions in CD-MOF-2 pull the protons away from the cyclodextrin alcohol groups, increasing their nucleophilic strength and turning them into strongly binding alkoxide chemisorption sites. At the same time, the diverse hydrogen bonding environments of the alkoxide sites reduce their nucleophilic character to a different extent, tuning their CO 2 binding to become irreversible, reversible, or weak. By linking the acid−base proton equilibrium and hydrogen bondingtwo chemical concepts widely used for liquidsto the strength of the CO 2 binding in CD-MOF-2, this work suggests new strategies for advancing design of tunable solid materials for CO 2 capture or detection.