Adsorption and electronic interactions of glycine on Al12N12 & B12N12 nanocages: A DFT study

Understanding how amino acids interact with nanostructured cages is useful for designing platforms for bio-interfaces, adsorption, and sensing. Here, first-principles DFT calculations were used to investigate the interaction of glycine with two inorganic nanocages, Al12N12 & B12N12, considering both vacuum and an aqueous (implicit) environment. Structural optimization and adsorption energetics were combined with electronic descriptors (frontier orbitals and global reactivity indices), molecular electrostatic potential (MEP) mapping, and bonding analyses using QTAIM/RDG and ELF. The results show that glycine forms stable adsorbed complexes on both cages, with stronger binding in water than in vacuum. In vacuum, adsorption energies are −25.32 (Al12N12) and − 28.45 kcal mol−1 (B12N12), while in water they increase to −34.37 (Al12N12) and − 36.21 kcal mol−1 (B12N12). Complex formation also increases dipole moments (e.g., from near-zero for pristine cages to 2.44–3.45 D for Al12N12 complexes and 1.06–1.77 D for B12N12 complexes) and modifies energy gaps and chemical descriptors, consistent with interfacial polarization and charge redistribution. QTAIM/RDG and ELF analyses indicate that stabilization is dominated by non covalent interactions (hydrogen bonding/electrostatic contributions), supported by measurable charge transfer (net transfer up to ∼0.23 e depending on the medium and cage). Overall, B12N12 shows slightly stronger adsorption than Al12N12, and the solvent environment enhances binding and electronic response, highlighting these nanocages as promising scaffolds for glycine-related adsorption/sensing studies.