SERS spectra of a bioactive carboximidamide derivative at different concentrations: Experimental and DFT investigations

In the current study (Z)-2-(2-oxoindolin-3-ylidene)hydrazine-1-carboximidamide hydrochloride's (OHC) Infrared (IR), Raman and surface-enhanced Raman scattering (SERS) spectra at various concentrations were presented experimentally and using density functional theory (DFT) simulations. Ag6, OHC and OHC-Ag6 systems’ structures were initially optimized. The OHC-Ag6 complex exhibits charge transfer interaction (CTI) between Ag and the OHC, according to frontier orbital molecular (FMO) analysis. The CTI under investigation was confirmed by molecular electrostatic potential (MEP) analysis. The molecule is chemisorbed on Ag6 in a tilted manner through the lone pair of atoms, according to SERS investigation. With changes in concentration, the interaction of OHC with metal also changes, resulting in orientation changes. Additionally, there was a strong correlation between theoretical findings and experimental values. Therefore, the current discovery opens the door for engineering robust SERS active substrates useful for creating OHC-related biosensors.