Molecular Orbital Theory of Chemical Reactions

Carbon-defect-driven persulfate activation for highly efficient degradation of extracellular DNA contaminant: Radical oxidation and electron transfer pathways

Extracellular DNA (eDNA), as a dynamic repository for antibiotic-resistant genes (ARGs), is a rising threat to public health. This work used a ball-milling method to enhance defect structures of activated carbon, and carbon defects exhibited an excellent capacity in persulfate (PS) activation for model eDNA and real ARGs degradation. The eDNA removal by defect-rich carbon with PS was 2.3-fold higher than that by unmilled activated carbon. The quenching experiment, electrochemical analysis and thermodynamic calculation showed that carbon defects could not only enhance the generation of SO₄^•- and ^•OH, but formed an electron transfer bridge between eDNA and PS, leading to the non-radical oxidation of eDNA. According to molecular calculations, the nitrogenous bases of DNA were the easiest sites to be oxidized by electron transfer pathway. This research offers a new way using defective carbon materials as PS activator for eDNA pollutants, and an insight into the non-radical mechanism of eDNA degradation.

Why Hoffmann? His Chemistry

Why was it that Roald Hoffmann was the perfect collaborator for R. B. Woodward for proposing the Principle of Conservation of Orbital Symmetry as the solution to the no-mechanism puzzle? This publication presents 17 "tools" that Hoffmann used extensively and effectively prior to the Woodward-Hoffmann collaboration that would he call upon reveal the mechanism of pericyclic reactions. In a sense, this is a biography of Hoffmann with a focus on his personal and professional skills as of May 5, 1964.

Kenichi Fukui, Frontier Molecular Orbital Theory, and the Woodward-Hoffmann Rules. Part I. The Person†

Kenichi Fukui shared the 1981 Nobel Prize in Chemistry with Roald Hoffmann for "their theories, developed independently, concerning the course of chemical reactions." This is Paper 4 - Part I, of a three-part trilogy within a 27-paper series on the history of the development of the Woodward-Hoffmann rules. The personality and professional style of Fukui is discussed as well as his style of teaching and his mottos and sayings. A brief chronological history of his academic and professional life is presented along with a listing of Fukui's great flexibility in behaviors and in science. Lastly, a short list of Fukui's key awards is provided.

Molecular orbital theory in cavity QED environments

Coupling between molecules and vacuum photon fields inside an optical cavity has proven to be an effective way to engineer molecular properties, in particular reactivity. To ease the rationalization of cavity induced effects we introduce an ab initio method leading to the first fully consistent molecular orbital theory for quantum electrodynamics environments. Our framework is non-perturbative and explains modifications of the electronic structure due to the interaction with the photon field. In this work, we show that the newly developed orbital theory can be used to predict cavity induced modifications of molecular reactivity and pinpoint classes of systems with significant cavity effects. We also investigate electronic cavity-induced modifications of reaction mechanisms in vibrational strong coupling regimes.

Theoretical description of light-matter coupling in the strong-coupling regime is challenging. Here the authors introduce a fully consistent ab-initio method of molecular orbital theory applicable to material systems in quantum electrodynamics environments.

Conformational analysis of tannic acid: Environment effects in electronic and reactivity properties

Polyphenols are natural molecules of crucial importance in many applications, of which tannic acid (TA) is one of the most abundant and established. Most high-value applications require precise control of TA interactions with the system of interest. However, the molecular structure of TA is still not comprehended at the atomic level, of which all electronic and reactivity properties depend. Here, we combine an enhanced sampling global optimization method with density functional theory (DFT)-based calculations to explore the conformational space of TA assisted by unsupervised machine learning visualization and then investigate its lowest energy conformers. We study the external environment's effect on the TA structure and properties. We find that vacuum favors compact structures by stabilizing peripheral atoms' weak interactions, while in water, the molecule adopts more open conformations. The frontier molecular orbitals of the conformers with the lowest harmonic vibrational free energy have a HOMO-LUMO energy gap of 2.21 (3.27) eV, increasing to 2.82 (3.88) eV in water, at the DFT generalized gradient approximation (and hybrid) level of theory. Structural differences also change the distribution of potential reactive sites. We establish the fundamental importance of accurate structural consideration in determining TA and related polyphenol interactions in relevant technological applications.