Tuning of the Electrostatic Potentials on the Surface of the Sulfur Atom in Organic Molecules: Theoretical Design and Experimental Assessment.

Noncovalent sulfur interactions are ubiquitous and play important roles in medicinal chemistry and organic optoelectronic materials. Quantum chemical calculations predicted that the electrostatic potentials on the surface of the sulfur atom in organic molecules could be tuned through the through-space effects of suitable substituents. This makes it possible to design different types of noncovalent sulfur interactions. The theoretical design was further confirmed by X-ray crystallographic experiments. The sulfur atom acts as the halogen atom acceptor to form the halogen bond in the cocrystal between 2,5-bis(2-pyridyl)-1,3,4-thiadiazole and 1,4-diiodotetrafluorobenzene, whereas it acts as the chalcogen atom donor to form the chalcogen bond in the cocrystal between 2,5-bis(3-pyridyl)-1,3,4-thiadiazole and 1,3,5-trifluoro-2,4,6-triiodobenzene.