The stoichiometric ratio 2:1 mix of 1-phenylpiperazine and oxalic acid dihydrate followed by slow evaporation results in a new material, bis(4-phenylpiperazin-1-ium) oxalate dihydrate, with the general chemical formula (C₁₀H₁₅N₂)₂(C₂O₄).2H₂O, indicated by PPOXH. The title compound’s asymmetric unit and three-dimensional network have been determined by single crystal X-ray diffraction. Intermolecular O-H…O, N-H…O and C-H…O hydrogen bonding assist in maintaining and stabilization of the crystal structure of this new compound. Hirshfeld surface analysis and two-dimensional fingerprints have been performed to quantify the non-covalent interactions in the PPOXH structure. The vibrational modes of the different characteristic groups of the title chemical were identified using infrared spectrum analysis. The thermal characterization of this product was studied by a coupled TG/DTA analysis. The ultraviolet-visible absorption spectrum has been used to study the optical properties and the energy gap of this compound. DFT calculations were employed to evaluate the composition and properties of PPOXH. The analysis of HOMO-LUMO frontier orbitals analysis allows us to understand the chemical reactivity of this supramolecular compound and to determine the electrophilic and nucleophilic sites responsible for electron transfer. Topological analysis (AIM), reduced density gradient (RDG), molecular electrostatic potential surface (MEPS) and Mulliken population were analyzed to evaluate the types of non-covalent interactions, localization of electrons in space, atomic charges and molecular polarity in depth.

In this paper, a novel hybrid material, entitled histaminium bis(trioxonitrate), with the general chemical formula (C₅H₁₁N₃)(NO₃)₂, denoted by HTN was presented. Single-crystal X-ray diffraction was used to determine the structural characteristics of this compound after it was made using a slow evaporation method at room temperature. This compound was elaborated and crystallized to the monoclinic system with space group P2₁/c, and the lattice parameters obtained were: a = 10.4807 (16)Å, b = 11.8747 (15)Å, c = 16.194 (2)Å, β = 95.095 (6)°, V = 2007.4 (5)ų and Z = 8. The title compound’s atomic structure couldbe modeled as a three-dimensional network. Organic cations and nitrate anions were connected via N–H...O and C–H...O hydrogen bonds in the HTN structure. The intermolecular interactions responsible for the formation of crystal packing were evaluated using Hirshfeld surfaces and two-dimensional fingerprint plots. The compound’s infrared spectrum, which ranged from 4000 to 400 cm⁻¹, confirmed the presence of the principal bands attributed to the internal modes of the organic cation and nitrate anions. Additionally, spectrofluorimetry and the ultraviolet–visible spectrum was used to investigate this compound. DFT calculations were used to evaluate the composition and properties of HTN. The energy gap, chemical reactivity and crystal stability of HTN were quantified by performing HOMO-LUMO frontier orbitals analysis. Topological analysis (AIM), Reduced Density Gradient (RDG), molecular electrostatic potential surface (MEPS) and Mulliken population were processed to determine the types of non-covalent interactions, atomic charges and molecular polarity in detail.

Three new cocrystals of Oxyma-B, an important racemization suppressor for peptide synthesis, with 6-methylquinoline (I), 2,3,5,6-tetramethylpyrazine (II), and 1,10-phenanthroline (III) were synthesized and their single crystal structures analyzed. They show a rich network of noncovalent interactions, including classical and nonclassical hydrogen bonds (CH···O, OH···N, CH···N), CH···π, π-stacking, and, notably, lone pair···π (n → π*) interactions. Distinctive supramolecular synthons were identified, including the R₂ ²(7) motif found in both 6-methylquinoline/Oxyma-B and 2,3,5,6-tetramethylpyrazine/Oxyma-B cocrystals. In 1,10-phenanthroline/Oxyma-B, larger ring motifs such as R₄ ⁴(20) and R₅ ⁵(24) were observed, further supported by additional synthons of types R ₁ ²(5) and R ₁ ²(6). Hirshfeld surface analysis and density functional theory (DFT) calculations, including MEP surface, QTAIM, and NCIplot analyses, were carried out to quantify the intermolecular contributions and rationalize the experimental findings with a focus on the cooperative role of hydrogen bonding, π-stacking, and lone pair···π (n → π*) interactions in stabilizing and shaping the architectures of these new multicomponent crystalline materials.

We report a combined crystallographic/computational study on a series of ammonium salts of fumaric and maleic acids. It has provided deeper insight into energetic and directional nature of the anion⋯anion contacts present in their molecular packing.