Utilizing intermolecular interactions involving organohalogens, which are often overlooked relative to more typical hydrogen bonding interactions involving N–H and O–H donor, molecular combinations involving organohalogens were designed to isolate solid cocrystals of two non-reacting liquids, as well as a deep eutectic solvent from two solids. The reaction of perfluoropyridine with dicyclohexylamine as well as 2-methylpiperdine, which are all liquids under ambient conditions, yielded rare examples of solid cocrystals. These crystals are thermally stable to 180°C or greater, over 100°C above the boiling point of perfluoropyridine. These cocrystals include extremely short N–H●●●F–C distances, including one with an H●●●F distance of 1.757(19) Å, which is the shortest amongst neutral amines reported to date. In contrast, the equimolar combination of 1,3-dithiane and 1,2-diiodotetrafluorobenzene, both of which are solids under ambient conditions, provided a liquid with a melting point of 13.7°C. This melting point is depressed from the predicted ideal melting point over a wide range of compositions, representing the first reported example of a hydrophobic deep eutectic solvent derived from halogen bonding.

Modifying phase behavior with organohalogens: N–H●●●F–C hydrogen bonding and halogen-bonding derived deep eutectic solvents

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.