QCM-Based Nano Schiff Base Quinazoline-methionine Hybrid Ligand Complex with Cobalt (II) As a Fast Response Nanosensor for Instantaneous Monitoring Water Pollutant Pb (II) Ions

Lead is an elemental substance with inherent toxicity that occurs naturally within the Earth's lithosphere. Its extensive utilization has led to widespread environmental pollution, human contact, and notable global public health effects across various regions. Continuous surveillance of "lead" concentrations in the ecosystem is imperative to minimizing potential hazards and human contact. This research delineates the synthesis and analysis of an innovative Schiff base ligand along with its corresponding ternary Co(II) complex, followed by its nanostructure's fabrication, characterization, and utilization. A Cobalt (II) coordination compound featuring a principal ligand denoted (LAMS) and an auxiliary ligand Methionine denoted (LMET) was synthesized and subjected to comprehensive characterization utilizing various analytical techniques, including FT-IR, UV-Vis, mass spectrometry, elemental analysis, and electric conductance measurements. Thermal behavior analysis (TGA) of the Cobalt (II) complex corroborated well with the proposed formula derived from the analytical data. Characterization outcomes revealed the molecular formula of the Cobalt (II) complex to be [(LAMS)(LMET)Co(Cl)].3H2O. The ligand (LAMS) exhibited tridentate chelation behavior by coordinating with the central Cobalt (II) metal ion through its two azomethine nitrogen groups, while (LMET) bound to the cobalt (II) metal ion via deprotonated hydroxyl oxygen and NH2 group, resulting in a distorted octahedral structure. The extensive characterization of the Nano Schiff base cobalt complex involved a variety of analytical techniques, including Dynamic Light Scattering (DLS), Zeta potential analysis, Atomic Force Microscopy (AFM), BET surface area determination, and pore size analysis. Furthermore, the potential application of the Nano Schiff base Cobalt complex as the Quartz Crystal Microbalance (QCM) stands out among sensing apparatuses, boasting a well-established status and acknowledged sensitivity in detecting molecules and biological assemblies. Renowned for its simplicity and cost-effectiveness, the QCM sensor holds promise, primarily focusing on detecting water contamination by Lead ions. The sensor's mechanical stability was also affirmed by investigating the applied ionophore's lipophilicity using contact angle measurements, revealing an average contact angle of 121.59 degrees. Notably, this attribute contributes to the robustness of the sensor. The sensor's responsiveness under differing pH and temperature conditions was carefully monitored, with a swift response time of less than 1 minute.