Multicomponent supramolecular assemblies of 1(2H)-Phthalazinone and Tetrafluoroterephthalic acid: Understanding the role of hydrogen bonding on the structure and properties using experimental and computational analyses.

Two novel cocrystals were successfully constructed by 1(2H)-Phthalazinone (PHT) and Tetrafluoroterephthalic acid (TETA) based on O-H⋯O, N-H⋯O, C-H⋯O, C-H⋯F, N-H⋯N and C-H⋯N hydrogen bonding networks, and were well depicted by single crystal diffraction analysis. As predicted by electrostatic potential analysis, the stoichiometry of PHT to TETA is 2:1 and stabilized by O-H⋯O and N-H⋯O hydrogen bonds. The single crystal X-ray diffraction characterized that the two cocrystals were all made up by 2PHT-TETA motif in different ways. AIM analysis and Hirshfeld surfaces indicated the adjacent 2PHT-TETA units assemble through C-H⋯O, C-H⋯F and C-H⋯N hydrogen bonds, producing a 2D plane structure in cocrystal I. Meanwhile, the C-H⋯F, N-H⋯N and C-H⋯O hydrogen bonds between 2PHT-TETA units were the stabilizing factors in cocrystal II. Topological parameters such as ∇ρ and H revealed the strength of hydrogen bonds were moderate in nature except O31⋯H32-O34 (1.704Å, -60.336kJmol) in compound I. The hydrogen bonding interactions, cocrystal stability and electron donor-acceptor interactions were investigated using natural bonding orbital analysis. It showed that electron transfer of n(O) σ*(O-H) and n(O) σ*(N-H) between PHT and TETA influence the packing characteristics significantly. Structural changes accompanying cocrystal process have been rationalized through the IR spectrum along with the quantum chemical calculations. The frequency downshifts of CO, N-H and O-H stretching after cocrystallization have been attributed to hydrogen bonding interactions.