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Computational chemistry is no longer seen as just an academic exercise. Researchers in academia and industry are now aware of the benefits associated with theoretical predictions of molecules. However, there is a skills-gap associated with teaching/learning the basics and the applications of computational chemistry. Herein, we describe the development and utilization of several quantum chemical exercises for educational purposes. 

Hydrogen is a versatile, energy-dense gas that can be used as an alternative to fossil fuels in many applications, including transportation and power generation. However, widespread adoption of hydrogen fuels is limited, in part, by the inability to safely store and transport hydrogen gas outside of carefully controlled industrial environments. An intriguing chemical phenomenon called the "molecular corking effect," may prove useful as a hydrogen gas storage mechanism. The molecular corking effect has been observed when hydrogen gas interacts with a class of materials called single-atom alloys (SAAs). SAAs consist of a relatively inert noble metal surface interspersed with single atoms of catalytically-active metals such as platinum and palladium. When diatomic hydrogen gas contacts the single-atom alloy, the bond between the two hydrogen atoms is broken by the catalytically-active metal. The individual hydrogen atoms then spill over on the inert metal surface. A "cork" molecule that preferentially binds to the catalytically-active metal can be added to prevent the hydrogen atoms from reforming gaseous hydrogen. Hydrogen can be safely stored in this manner until the temperature is increased to remove the cork molecule and release the hydrogen gas from the surface. Fundamental insights into the entire molecular corking process must be developed to fully realize the potential of single-atom alloy hydrogen storage. To these ends, we utilize non-local density functional theory (DFT) to investigate the potential of N-heterocyclic carbenes (NHCs) to behave as these so-called “molecular corks”, given their modular σ-donating/π-accepting abilities. 

We utilize non-local density functional theory (DFT) to investigate the potential of N-heterocyclic carbenes (NHCs) to be utilized as “molecular corks” on single atom alloys (SAAs) of Pd/Cu(111) and Pt/Cu(111). We discuss an intriguing chemical phenomenon called the "molecular corking effect," which may prove useful as a hydrogen gas storage mechanism. Given the modular σ-donating/π-accepting abilities, and large synthetic library of NHCs, this class of compounds are investigated. We utilize a molecular orbital (MO) approach to understand/explain the NHC-SAA interface to fundamentally understand how these molecules anchor themselves to metal surfaces. 

We provide a summary of contemporary computational tools utilized in the study of adsorbate interactions with solid-state materials from the perspective of a quantum chemist. This work contains a focused theoretical primer of interactions between the molecular orbitals of an adsorbate and the electronic bands of a solid as well as a review of the promising methodologies for disentangling these contributions. We apply these tools in a methodological fashion to density functional theory (DFT) calculations of molecular hydrogen (H2), H2 adsorbed to the pristine Cu(111) surface, and H2 adsorbed to a single atom alloy comprised of palladium and copper (Pd/Cu(111)) to provide chemically intuitive explanations of bonding in these systems. 

Not AvailThe on-surface synthesis of various organic compounds relies on the self-assembly and subsequent dissociation of halogen-substituted organic molecules for polymerization and functionalization. Here, we demonstrate that the photolytic disassembly and dissociation of bromobenzene molecules within magic-sized tetramer nanoclusters are influenced by halogen bonding on the Cu(111) surface. We explain this phenomenon using a combination of two-photon photoemission spectroscopy, scanning tunneling microscopy, and density functional theory computations. The interactions that determine the preferred cluster sizes of trimers to pentamers arise from a combination of halogen bonding and weak hydrogen bonding. Surface adsorption enhances halogen bonding while weakening the weak hydrogen bonds in the nanoclusters. The most stable tetramers are constructed from a trimer foundation that employs halogen-3 synthons with an exterior fourth molecule. The exterior bromobenzene in this tetramer may detach from the trimer core cluster or undergo dehalogenation before the other bromobenzene molecules under irradiation. The work function of the Cu(111) surface is significantly decreased by the presence of a tetramer. This reduction facilitates the photodissociation of bromobenzene by allowing electrons from the surface to occupy the antibonding molecular orbitals associated with the C–Br bond. The work function increases steadily as smaller clusters and dissociated bromobenzene (phenyl and Br) are formed photolytically. The molecules of the trimers are not photodissociated because the energy levels of the C–Br antibonding orbitals in the trimer core are notably higher in energy than those of the exterior molecule in the tetramer. Our study highlights the potential of weak noncovalent interactions to guide selective photolytic reactions on surfaces.able 

We explore the charge transfer events four different classes of N-heterocyclic carbenes (NHCs) with a Pd/Cu(111) single atom alloy surface. We provide a frontier molecular orbital approach to understand similarities and differences between these systems. We demonstrate that this approach can be applied to the PDOS, COHP, and molecular charges to better understand the surface-adsorbate system. Density of This work emphasizes the composition- and geometry-dependent nature of NHC adsorption on SAAs and provides insights into tailoring these systems for catalytic and storage applications. 

Molecular corking is a phenomenon where a molecule selectively binds to the catalytic atom of a single-atom alloy (SAA) and prevents the recombination of atomized gas molecules at the surface of a metal, functionally trapping them. A necessary feature of a molecular cork is strong, yet reversible binding and thermal stability. There is active experimental and theoretical research on potential candidates, which rank the viability of molecular corks based on their ability to donate electrons into sigma bonds and accept back-donation from the metal via pi bonding. This is often assessed experimentally and computationally using chemical shifts in NMR of selenium and phosphorus adducts as well as other metal complexes. A prime candidate for this purpose are N-heterocyclic carbenes (NHC). However, there have been few studies that perform bond decomposition analysis of periodic quantum mechanical calculations to qualify if the observed chemical shifts in NMR and binding strengths on metals are in fact due to sigma donation and pi back bonding. Moreover, the role of conformational flexibility plays in reported NMR chemical shifts is relatively unexplored. Using periodic vdW-DFT calculations and localized bonding MOs extracted from periodic plane-wave basis sets, along with molecular calculations, we seek to answer these questions for simple, but representative molecular systems bound to Cu-Pd SAA surfaces. 

This study investigates the integration of generative artificial intelligence (Gen AI) into a General Chemistry II laboratory at St. Bonaventure University to assess its impact on student learning, inquiry, and chemical reasoning. In a redesigned of a common thermodynamics/equilibrium experiment involving cobalt(II) chloride, students used ChatGPT and a retrieval-augmented Gen AI (BonnieChemBot) to assist in calculating equilibrium constants, thermodynamic values, and answering open-ended chemical questions. The lab targeted four key educational goals: (A) mastery of chemical concepts, (B) development of prompt engineering strategies, (C) facilitation of inquiry-driven dialogue with instructors, and (D) critical evaluation of Gen AI outputs by students using chemical intuition. Students attempted all analyses twice: first independently, then with the assistance of Gen AI. Finally, they were asked to reflect on their trust in the Gen AI solutions and generate final answers. Instructor intervention in post-lab analyses was limited to cases where students had clearly attempted the first two steps in this process. While students were encouraged to practice prompt engineering, no grades were assigned to its execution. Instead, grading focused solely on students’ final answers. 

We apply non-local density functional theory calculations to determine the impact of backbones and functionalization of different N-heterocyclic carbenes (NHCs) adsorbed to different single atom alloys (SAAs). A frontier molecular orbital approach is applied to these systems to understand the chemistry occurring. The Local Orbital Basis Suite Towards Electronic-Structure Reconstruction (LOBSTER) program was utilized to project an atomic orbital (AO) basis from our PAW simulations to allow for a MO-oriented bonding analysis MOs of the adsorbate molecules were extracted from our planewave VASP calculations utilizing the linear combination of fragment orbitals (LCFO) method implemented in LOBSTER.