Structural, Hirshfeld Surface and HOMO-LUMO gap analysis of five co-crystals of 2-amino-5-chloropyridine or 2-amino-bromopyridine with isomeric methylbenzoic acids

Abstract The 1:1 co-crystals formed between 2-amino-5-chloropyridine/2-amino-5-bromopyridine and isomeric n-methyl-benzoic acids [n = 2, 3 and 4] are described. The co-crystals with the n = 2 co-former are isostructural. The co-formers are linked by intermolecular hydrogen bonds involving amino-N–H⋯O(carbonyl) and hydroxyl-O–H⋯N(pyridine). Additional and comparable amino-N–H⋯O(carbonyl) hydrogen bonds were evident in all co-crystals and play an important role in stabilising the molecular packing. The intermolecular interactions were also analysed through the calculated Hirshfeld surfaces. The charge transfer occurring between the calculated HOMO-LUMO states suggests electron mobility within the co-crystals owing to the aforementioned hydrogen bonding.