Structural and electronic properties of AgNPs adsorbed by glucose molecules determined using DFT theory

In order to build and design stable molecular structures of α-D-glucose molecules after adding to a cluster of silver atoms, an optimization process was precisely carried out for α-D glucose/Ag3 molecule at low energy. The correlation between glucose molecule and silver atoms is evaluated by investigating configurational and electronic features of the named molecules by adopting the Density functional theory DFT using the hybrid B3LYP functional and 6-311+G∗ as a basis set for C, O, and H atoms, while LANL2DZ set for silver (Ag) atoms. Frequencies of vibrational modes are essential analyses that have been instrumental in understanding the IR spectra of studied molecules. These analyses enable the detection of the active groups along the spectrum chart including C-O-C, C=O, C-O, O-H, C-C and C-H peaks confirming the previous experimental findings. Another important finding is the energy gap (E ) obtained by the difference between the higher occupied molecular orbital (HOMO) and lower unoccupied molecular orbital (LUMO). Remarkably, E was found to increase from 3.440 to 4.358 eV in a configuration consisting of two glucose molecules with one Ag atom (2α-D glucose/Ag-C₁₂H₂₄O₁₂Ag) to another with one glucose molecule with three Ag atoms (α-D glucose/Ag3-C₆H₁₂O₆Ag₃) configuration. Additionally, the potential of the molecular electrostatic isosurface (MEP) in 3D diagram for two configurations is clarified by the colour-coded bar with the distributions of charge density distributions to examine the nucleophilicity and electrophilicity behaviour.