Investigation of supramolecular synthons of p-hydroxybenzoic acid (PHBA): Comparison of its hydrate, co-crystal and salt

•Three different kinds of supramolecular syntheses of PHBA have been carried out and characterized.•The hydrogen bonding motif in the solid state has been investigated by vibrational spectroscopy.•The intermolecular contacts of crystal structure have been revealed by Hirshfeld surfaces.

An investigation of supramolecular synthons of p-hydroxybenzoic acid (PHBA) has been carried out in this work. Three different kinds of compounds derived from PHBA (hydrate (1), co-crystal (2) and salt (3)) have been synthesized and characterized by single-crystal X-ray diffraction, infrared spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). A thorough structural investigation revealed the different supramolecular synthons patterns of the three compounds: hydrate (1)—displays 1-D supramolecular sheet completed by water molecules; co-crystal (2)—displays square grid structure completed by hetero-dimeric unit; and salt (3)—forms hetero-dimeric unit and displays infinite zigzag striped structure. We further prepared Hirshfeld surfaces for compounds 1–3 as well as PHBA, accompanied by vibrational spectroscopy, for the in-depth studies of intermolecular interactions in their solid-state forms.