Symmetrical Bifurcated Halogen Bond: Design and Synthesis

The main purpose of this work is to extend the application of the symmetrical bifurcated halogen bond in crystal engineering. For this purpose, the optimization of this supramolecular synthon was performed first by using quantum mechanical calculations. The results obtained from theoretical calculations showed that 1,4-diiodotetrafluorobenzene, 1,10-phenanthroline-5,6-dione, and 4,4',6,6'-tetramethyl-2,2'-bipyrimidine are good candidates for the formation of the symmetrical bifurcated halogen bond. This was further confirmed by the successful synthesis of two cocrystals that are composed of the three compounds and formed mainly via symmetrical bifurcated halogen bonds. The good agreement between the theoretical design and the experimental synthesis also indicates that the quantum mechanical calculation can play an important role in increasing the probability of discovering useful supramolecular synthons.