System for the synthesis and evaluation of novel Schiff base metal complexes

Abstract

A system for the synthesis of a Schiff base ligand and its Cd(II) and Zr(OH)2(IV) metal complexes, comprising modules for synthesis, coordination, purification and spectroscopic characterization.

Description

Field of invention

[0001] The invention relates to a system for the synthesis, characterization and biological evaluation of Cd(II) and Zr(OH)2(IV) complexes derived from a novel Schiff base ligand. Background of the invention

[0002] Schiff bases with heterocyclic thiadiazole and phenol groups have attracted considerable attention due to their versatile coordination possibilities and biological relevance. Metal complexes derived from such ligands often exhibit enhanced antimicrobial, DNA-cleaving, and anticancer activity compared to the free ligands. Traditional synthesis and evaluation of these complexes require several independent steps, including ligand preparation, metal coordination, spectroscopic confirmation, and biological assays, which can compromise reproducibility and efficiency. There is a need for an integrated system that combines controlled Schiff base synthesis, systematic formation of Cd(II) and Zr(OH)₂(IV) complexes, and comprehensive spectroscopic characterization.Furthermore, biological evaluation—including DNA cleavage, antimicrobial activity, anticancer potency, and computational modeling—benefits from a unified workflow that ensures standardized assessment. The invention fulfills the need for an organized system for the production of structurally validated metal complexes and the evaluation of their biological properties, thereby enabling the identification of promising antimicrobial and anticancer candidates. Summary of the invention:

[0003] The invention provides a system for the synthesis of a novel Schiff base ligand, 5-bromo-2-((5-mercapto-1,3,4-thiadiazol-2-ylimino)methyl)phenol (LH), and for the subsequent preparation of its cadmium(II) and zirconium(IV) hydroxide complexes. The system comprises modules for controlled ligand synthesis, metal complex formation, purification, and spectroscopic characterization. Techniques such as FTIR, UV-Vis spectroscopy, NMR, mass spectrometry, elemental analysis, and conductivity measurements are integrated to verify structural integrity and confirm the non-electrolytic nature of the synthesized complexes. The system also includes biological evaluation units for assessing DNA cleavage, antimicrobial performance, anticancer potential, and for computational modeling.The cadmium complex shows superior antimicrobial activity, higher antifungal efficacy, and the strongest anticancer potency with an IC. 50 A value of 32.49 µM was obtained. Density functional theory analyses and molecular docking simulations provide additional insights into the complexes and confirm strong binding affinities and electronic properties consistent with the biological results. The system thus enables optimized synthesis, analysis, and evaluation of metal-based therapeutic candidates. Detailed description

[0004] The system begins with a ligand synthesis module in which Schiff's base LH is prepared by condensation of the thiadiazole derivative with the bromophenolaldehyde under controlled reaction conditions. Maintaining suitable temperature, pH, and reagent concentrations in the synthesis environment ensures reproducibility and the formation of highly pure ligands. Purification steps such as filtration and recrystallization provide a stable ligand for subsequent metal complexation.

[0005] In the metal coordination module, the ligand reacts with cadmium(II) or zirconium(IV) hydroxide precursors to form [Cd(LH)₂(MeOH)₂] and [Zr(OH)₂(LH)₂] complexes. Stoichiometric control and mixing conditions ensure the formation of well-defined coordination structures. The system allows for adjustment of solvent, temperature, and reaction time to optimize yield and structural consistency. A spectroscopic characterization platform is integrated to confirm complex formation. FTIR analysis confirms the ligand-metal bond through characteristic shifts in the frequencies of functional groups. NMR spectroscopy provides structural information about the ligand environment, while UV-Vis spectra reveal electronic transitions indicative of complex stability. Mass spectrometry and elemental analysis support the proposed molecular compositions.Measurements of molar conductivity confirm the non-electrolytic character of both complexes.

[0006] For biological evaluation, the system is equipped with a unit for DNA cleavage analysis. The complexes are tested under controlled conditions for their ability to cleave biomolecular DNA, allowing analysis of their nuclease-like behavior. The results confirm significant DNA cleavage for both cadmium and zirconium complexes.

[0007] An antimicrobial test module evaluates the activity of the ligand and the complexes against strains such as Staphylococcus aureus, Bacillus subtilis, Fusarium oxysporum, and Candida albicans. The cadmium complex demonstrates superior antibacterial and antifungal activity with inhibition zones of 15–24 mm, depending on the organism tested.

[0008] The module for evaluating anticancer activity includes cytotoxicity studies with the neuroblastoma cell line SH-SY-5Y. The cadmium complex exhibits an IC 50 A value of 32.49 µM shows the highest anti-cancer effect and thus demonstrates a promising therapeutic potential.

[0009] The system also includes computer-aided modeling tools for density functional theory calculations. These analyses show that the cadmium complex has a smaller HOMO-LUMO energy gap, increased electrophilicity, and a higher electron acceptor capability, which is consistent with its improved biological properties.

[0010] A molecular docking simulation unit evaluates the interaction of the complexes with DNA and human serum albumin (HSA). The cadmium complex shows the strongest binding with a docking score of -6.39 kcal / mol, confirming its observed biological activity.

[0011] Together, these modules form an integrated system for the synthesis, characterization, and biological evaluation of Schiff base metal complexes. This improves efficiency and enables the identification of potential therapeutics.

Claims

[1] A system for the synthesis of a Schiff base ligand and its Cd(II) and Zr(OH)2(IV) metal complexes, comprising modules for synthesis, coordination, purification and spectroscopic characterization. [2] System according to claim 1, wherein the characterization comprises FTIR, UV-Vis, NMR, mass spectrometry, elemental analysis and conductivity measurements to confirm the structural composition and non-electrolytic character. [3] System according to claim 1, comprising an integrated platform for biological evaluation of DNA cleavage, antimicrobial activity, antitumor activity and computer-aided modeling of the synthesized metal complexes. [4] Metal complex produced by a system according to one of the preceding claims with improved antimicrobial and antitumor activity, demonstrated by DFT and molecular docking studies using the spectroscopic characterization module.