Six halogen-bonded cocrystals involving aromatic donors have been studied by far-IR spectroscopy. Characteristic redshift and intensity enhancement of the C-I stretching band have been observed, which provided a distinct signature of the halogen bond involving iodopentafluorobenzene.
Vasylyeva, V., Catalano, L., Nervi, C., Gobetto, R., Metrangolo, P., & Resnati, G. (2016). Characteristic redshift and intensity enhancement as far-IR fingerprints of the halogen bond involving aromatic donors. CrystEngComm, 18(13), 2247-2250. https://doi.org/10.1039/c5ce02385h