Solvent‐Dependent Adsorption and Sensing of Glycine on Coinage Metal Cluster Tetramer Nanoclusters (Ag, Au, Cu): A DFT/MD Study of Binding Motifs, Charge Transfer, and Optical Signatures
Jamelah S. Al‐Otaibi, Fowzia S. Alamro, Aljawhara H. Almugrin, Y. Sheena Mary, Gaurav Jhaa, Baiju Vasudevan, Maria Cristina GamberiniABSTRACT
Understanding how amino acids bind to coinage‐metal nanostructures is important for designing biointerfaces, catalysts, and chemical sensors. This study examines glycine adsorption on coinage‐metal tetramers of the type X 3 Y (X, Y = Ag, Au, Cu) in both vacuum and aqueous environments. Two binding motifs are analyzed: carbonyl‐anchored (D1, C═O) and amine‐anchored (D2, NH 2 ). Density‐functional theory calculations at the B3LYP‐D3(BJ) level with mixed basis sets and ECPs for metals are used to optimize geometries and evaluate adsorption energies, electronic descriptors, charge redistribution, and spectroscopic signatures. Results show that D2 binding is consistently more stable than D1 across all cluster compositions. Solvation significantly strengthens adsorption and increases dipole moments and polarizabilities, indicating enhanced polarization in water. Alloying with Au or Cu modifies orbital localization and charge‐transfer pathways, affecting reactivity and optical responses. Desorption analysis at 400 K suggests reversible sensing in vacuum but stronger, sometimes irreversible adsorption in aqueous media.