Two novel complexes, [(C₇H₁₀NO₂)CdCl₃]_n(I) and [(C₇H₉NO₂)CuCl₂],havebeen synthesized and characterized. Single crystal X-ray diffraction revealed that in compound (I), 2,6-dimethanol pyridinium acts as a monodentate ligand through the O atom of the hydroxyl group. Contrarily, the 2,6-dimethanol pyridine ligand interacts tridentately with the Cu(II) ion via the nitrogen atoms and the two oxygen (O, O’) atoms of the two hydroxyl groups. The structure’s intermolecular interactions were studied using contact enrichment ratios and Hirshfeld surfaces. Following metal coordination, numerous hydrogen connections between entities and parallel displacement stacking interactions between pyridine rings dictate the crystal packing of both compounds. The aromatic cycles generate layers in the crystal for both substances. Powder XRD measurements confirmed the crystalline sample phase purity. SEM confirmed the surface homogeneity, whereas EDX semi-quantitative analysis corroborated the composition. IR spectroscopy identified vibrational absorption bands, while optical UV-visible absorption spectroscopy investigated optical properties. The thermal stability of the two materials was tested using TG-DTA.

The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 2,5-dichloro-p-phenylendiaminium decachlorotricadmate(II) hexahydrate complex, (C₆H₈Cl₂N₂)₂[Cd₃Cl₁₀]·6H₂O, has been reported. The atomic arrangement can be described as built up by an anionic framework, formed by edge-sharing [CdCl₆]²⁻ octahedra in linear polymeric chains spreading along the a-axis, while the organic cations surround these latters. The inspection of the Hirshfeld surface analysis helps to discuss the strength of hydrogen bonds and to quantify the inter-contacts, which reveal that H…Cl/Cl…H (38.9%), H…H (13.9%), and Cd…Cl/Cl…Cd (12.4%) are the main interactions that govern the crystal packing of the studied structure. SEM/EDXwas carried out and the powder XRD confirmed the good crystallinity of the material. FT-IR and the DFT calculation reveal the good correlation between the experimental and the theoretical wavenumbers. The HOMO-LUMO energy gap was used to predict the electric conductivity of the compound. Finally, the thermal TGA/DTA analysis shows stability until 380 K.

The structural, optical spectroscopic, and density functional theory calculations of 2,4-Bis[4-(N,N-diisobutylamino)−2,6-dihydroxyphenyl] squaraine dye (SQ) are promising investigations that can be useful in photochemical mechanisms explanation and in designing promising chemosensors. The nature of the bonds, the chemical composition of SQ, crystallographic structure, morphology, and quality characteristics were explored by FTIR, XRD, and SEM investigations. The crystallite size, the dislocation density, and the lattice strain were found to be 57.3 nm, 3.045 × 10⁻⁴ nm^−2, and 3.065 × 10⁻³, respectively. The spectrum behavior of the absorbance and molar absorption coefficient spectra of SQ in DCM with three concentrations were analyzed to get some important optical properties of SQ dye. The determined optical gap transition equals E g a p o p t = 1.81 eV . Quantum chemical computations and optimized molecular geometries identified where electrophilic attacks are likely and analyzed the molecule’s electrostatic potential. Using DFT calculations at the B3LYP/6-31+G(d,p) level, the electronic structure of the squaraine molecule was confirmed, showing a HOMO–LUMO gap of 1.73 eV. MEP analysis indicated that the oxygen atoms are electron-rich, suggesting potential for hydrogen bonding and electrophilic interactions.