Biligand Complexes of Cholesterol and Thiocholesterol with Silver Nanoclusters: Experimental Data and DFT-Modeling

Abstract

TEM experimental data for “Silver–Cholesterol” (Ag–Ch) and “Silver–Thiocholesterol” (Ag–TCh) systems showed the formation of silver nanoclusters of (6.0 ± 0.5) nm and (2.0 ± 0.5) nm in size correspondingly. Supramolecular organization of the systems due to donor-acceptor or electrostatic interactions with cholesteric ligands led to the formation of elongated helix aggregates with plasmonic absorbtion in visible and near-IR spectral regions. Using the DFT /B3LYP5 method the structures of biligand complexes of Ag₁₃ silver cluster with cholesteric ligands Ch and TCh were modeled and compared with the structure of monoligand complexes. O- and S-containing ligands were coordinated by vertices on different sides of the Ag₁₃ icosahedron. The energies of model reactions of the formation of monoligand and biligand complexes are compared. A tendency of the Ag₁₃ metal cluster to attach more ligands was found out. It can be assumed that the system retains the tendency of further aggregation with the attaching of the additional ligand molecules.