Hydrogen Bonding versus Halogen Bonding in Host–Guest Compounds

The similarity and differences of the three host compounds H1 = 9,9′-(biphenyl-2,2′-diyl)difluoren-9-ol, H2 = 2,2′,7,7′-tetrabromo-9,9′-(biphenyl-2,2′-diyl)difluoren-9-ol, and H3 = 2,2′,7,7′-tetra- tert -butyl-9,9′-(1,4-phenylene)difluoren-9-ol which form inclusion compounds with 3-bromopyridine and its chloro-analogue guest are compared with respect to hydrogen bonding and halogen bonding. In all cases the hydrogen bonding motif (Host)O–H···O(Host)–H···N(Guest) predominates while the halogen···halogen interactions are of secondary importance in the packing of the structures. The structural data are supported by thermal analysis, Hirshfeld surface analysis, and IR spectroscopy.