The crystallographic study of 2,2’-((4-bromophenyl)methylene)bis(3-hydroxy-5,5-dimethylcyclohex-2-en-1-one) reveals that the compound crystallizes in the centrosymmetric space group P21/c. In the solid state, the structure of the title compound exhibits two strong intramolecular O−H· · · O hydrogen bonding interactions. Further, molecules of the title compound are self-assembled by weak intermolecular C−H· · ·O, π · · · π and H· · · H and C−H· · · Br contacts. Various intermolecular interaction that exist in the crystal structure and theirenergetics are quantified using PIXEL, DFT and QTAIM analyses. Six different motifs are identified from the PIXEL calculation. Lattice energy calculation suggests that the dispersion energy has the highest contribution for the crystal formation. The relative contributions of various intermolecular contacts in the title compound and its closely related analogs are evaluated using Hirshfeld surface analysis and the decomposed fingerprint plots. The common packing features exist between the title compound and its related analogs are identified.The quantitative molecular electrostatic potential surface diagram depicts the potential binding sites which are in good agreement with the crystal structure of the title compound. The structures of title compound in gas and solvent phases are compared with the experimental structure and reveals that they are superimposed very well. The vibrational modes of the monomer and four most stabilized dimers are characterized using both the experimental and DFT calculations. The UV-Vis spectrum is calculated using time dependent-DFT (TD-DFT) method and compared with experimental spectrum. The results indicate that the calculated energy of absorbance and oscillator strength correlate well with the experimental data.

Single crystals of two pyridine isomers containing cyano and thiophene moieties {systematic names: (Z)-2-(pyridine-2-yl)-3-(thiophen-2-yl)acrylonitrile, C₁₂H₈N₂S, I and (Z)-2-(pyridine-3-yl)-3-(thiophen-2-yl)acrylonitrile, C₁₂H₈N₂S, II} were obtained from ethanol-cyclohexane mixture. The thiophene ring wasfound to be disordered over two orientations (syn and anti) in II. The potential energy surface scan of thiophene ring rotation suggests that the syn conformer is more stable by ≈4 kcal mol−1 than that of the anti-conformer. The optimized structures obtained using the DFTmethod (M06-2X/cc-pVTZ level of theory) showa high degree of similarity with the experimental structures. A detailed experimental and theoretical analysis on the intra- and intermolecular interactions observed in these structures is reported. The molecules arranged in the crystalline state are completely different in I and II. Intermolecular interactions are qualitatively analyzed using Hirshfeld surface and its associated 2D fingerprint plots. The intermolecular interaction energies of different molecular pairs are calculated using the PIXEL method. Several weak non-covalent interactions such as C–H · · ·N, C–H · · ·π, C–H · · ·S, π· · ·π and S · · · N contacts play a vital role in the stabilization of crystal structures. These interactions are further explored by the topological analysis of the electron density based on the quantum theory of the atoms-in-molecules approach.