Theoretical structural study of van der Waals complexes between oxazole and atmospheric gases CO2 and N2 for capture applications.

Background The objective of this study is to explore the potential of oxazole (C ₃ H ₃ NO), a fascinating heterocyclic compound naturally present, which is a potential ligand in the construction of Metal-Organic Frameworks (MOFs) for the selective capture of CO ₂ in a nitrogen-rich atmosphere, using both molecular and solid-state simulation techniques. Methods This study investigates the equilibrium structures and binding energies of van der Waals aggregates formed by an oxazole molecule with nonpolar molecules such as CO ₂ and N ₂ , considering both two-body systems (oxazole@CO ₂ and oxazole@N ₂ ) and three-body systems (oxazole@CO ₂ @N ₂ and oxazole-CO ₂ /N ₂ @Au ₆ /Cu ₆ /Zn ₃ O ₃ ). Molecular computations for these systems are conducted using ab initio calculations at the MP2/aug-cc-pVXZ level of theory, where X = (D, T). Additionally, solid-state simulations analyze the adsorption behaviors and energies of oxazole@CO ₂ and oxazole@N ₂ on metallic surfaces:Au, Cu and ZnO(111) through Monte Carlo methods. Results We find that the oxazole exhibits more adsorption selectivity for CO ₂ than for N ₂ . Adding a second gas to the most stable complexes, oxazole@CO ₂ and oxazole@N ₂ , the oxazole capture ability does not vary. On the contrary, it strengthens the adsorption energy of three-body complexes compared to two-body complexes. The addition of metallic clusters (Au ₆ , Cu ₆ , Zn ₃ O ₃ ) and metallic surfaces (Au, Cu, ZnO) enhances the adsorption capacity, where Cu ₆ is particularly efficient. Both ZnO and Cu surfaces offer significant adsorption advantages while remaining economically feasible. Conclusions This study demonstrates that oxazole exhibits a strong selectivity for CO ₂ over N ₂ , with the addition of metallic clusters and surfaces significantly enhancing its adsorption capacity. These findings highlight the potential of oxazole-based materials for effective gas capture and separation, with positive implications for environmental sustainability.