Newly Fabricated Thiobarbiturate Mannich Base Derived Metal Complexes and its Larvicidal, Antifeedant and Molecular Docking Studies

Inorganic elements are essential in ecological therapies and it is clear that numerous organic substances utilized in healthcare do not operate only through organic mechanisms; a few are triggered or biotransformed by the metabolism of metal ions. The chemistry of Mannich bases and its metal complex counterparts has garnered considerable attention owing to its diverse uses. The primary aim of this article is to report the synthesis of Mannich-base and its chelating properties with various metal chlorides including Cu(II), Ni(II), Co(II), Fe(II) and Mn(II). The novel Mannich base ligand, 5-(hydrazinyl(2-hydroxyphenyl)methyl)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione, was synthesized through the reaction of thiobarbituric acid, salicylaldehyde and hydrazine hydrate. The ligand and its metal(II) complexes were characterized through analytical and spectral techniques including nuclear magnetic resonance spectroscopy (1H NMR and 13C NMR), electron paramagnetic resonance spectroscopy (EPR), ultraviolet and visible spectroscopy (UV-Vis) and Fourier transform infrared spectroscopy (FT-IR). The ligand and its metal(II) complexes were screened for their larvicidal efficacy towards the south-urban mosquito larvae Culex quinquefasciatus and assessed for toxicity towards non-target aquatic organisms. The copper(II) complex demonstrated significant larvicidal activity (LC50 = 20.83 µg/mL) than free ligand and control permethrin.