Crystallographic insights into the structural aspects of thioctic acid based halogen-bond donor for the functionalization of gold nanoparticles

The synthesis and self-assembly capabilities of a new halogen-bond donor ligand, 2,3,5,6-tetrafluoro-4-iodophenyl 5-(1,2-dithiolan-3-yl)pentanoate (1), are reported. The crystal structure of ligand (1) and the formation of a cocrystal with 1,2-di(4-pyridyl)ethylene, (1)·(2), both show halogen bonds involving the 4-iodotetrafluorobenzene moiety. Ligand (1), being a self-complementary unit, forms an infinite halogen-bonded chain driven by the S...I synthon, while the cocrystal (1)·(2) self-assembles into a discrete trimeric entity driven by the N...I synthon. Ligand (1) was also successfully used to functionalize the surface of gold nanoparticles, AuNP-(1). Experiments on the dispersibility profile of AuNP-(1) demonstrated the potential of halogen bonding in facilitating the dispersion of modified NPs with halogen-bond donors in pyridine. The aim of this research is to perform a complete structural description of a new halogen bonding (XB) donor, which will be used for the surface functionalization of gold nanoparticles (AuNPs). Crystallographic studies of simple model systems will be used to determine the recognition capabilities of the synthesized XB donor, and the functionalization of the AuNPs with the XB donor and their solubility profile in different solvents will be described.