SERS Spectra and MD Simulations of a Bioactive Diiodobenzaldehyde Derivative: Experimental and Theoretical Investigations

Ag3 clusters at distinct reactive sites are used to theoretically analyze the experimental SERS spectra of (1E,1"E)-O,O"-[(3,6-dioxopiperazine-2,5-diyl)bis(methylene)]bis[1-(2-hydroxy-3,5-diiodophenyl)-2-hydroxy-3,5-diiodobenzaldehyde oxime] (DBD) at varied concentrations. Ag3 is adsorbed with DBD in three distinct configurations, the first of which is the stable one, with adsorption energies of -17.37, -7.79, and -9.51 kcal/mol. Because the adsorption energies are negative, all adsorption points to a chemisorptions process. Among different concentrations, SERS is most noticeable around 10-5 M concentration. Following adsorption with Ag3, all changes in thermo dynamic terms are negative indicating that the adsorption is exothermic and spontaneous, leading to chemisorptions. After adsorption with Ag3, the UV-vis absorption of DBD is redshifted to extremely high levels at 349 nm. The chemical DBD interacts hydrophobically and hydrogen-formingly with amino acids, and it has a binding affinity of -9.4 kcal/mol with cycloserine targets. MD simulations were used to examine the dynamic alterations brought about by target protein binding.