Sonochemical syntheses of a nano lead (II) coordination compounds: Hirshfeld surface analyses, NCI–RDG, thermal, optical properties and structural characterization

In this study, a new lead(II) coordination complex, [Pb(Neo)(TCA)₂], was synthesized using both a branched tube diffusion method to obtain single crystals and a sonochemical route to produce its nanostructured form. The crystalline phase of the complex was confirmed by single-crystal X-ray diffraction, revealing a monoclinic system ( C2/c space group) with a distorted six-coordinate PbN₂O₄ geometry, influenced by the stereoactive lone pair of Pb(II). Nanostructures were prepared under ultrasonic irradiation, and their morphology was found to be strongly dependent on precursor concentrations, yielding particle sizes ranging from 64 to 100 nm as observed by SEM. The XRD patterns of the bulk and nanostructured samples closely matched, confirming identical phases with an average crystallite size of approximately 66.9 nm. Thermal analyses (TGA/DTA) demonstrated that the nanostructured form decomposes at slightly lower temperatures compared to the bulk material, due to its higher surface energy. Optical studies revealed that both forms exhibit π → π* transitions, with a slight blue shift in the absorption and emission spectra for the nanoparticles, consistent with size-dependent optical behavior. Controlled thermal decomposition of the nanostructured complex produced orthorhombic PbO nanoparticles with an average size of ~59 nm. Furthermore, Hirshfeld surface analysis, interaction energy calculations, and NCI-RDG analysis provided detailed insights into the intermolecular interactions governing crystal packing and supramolecular architecture.