In order to find out the consequences of a phenyl for pyridyl exchange on the crystalline packing behaviour of the parent compound 9-phenyl-9-fluorenol, three analogous 9-pyridyl substituted 9-fluorenols featuring the pyridyl ring in different linkage positions were comparatively studied with regard to their crystal structures. While the molecular structures in the crystal are not noticeably altered, the network structures are, showing the leading influence of the nitrogen atom to cause a variation of contact modes. Corresponding to the substitution site of the pyridyl group, these involve intra- and intermolecular hydrogen bonds, including helical and linear strand formation.
