Green tea dye ligands to transfer toxic lead metal ions to precipitated metal complexes for polymer composite applications

The synthesis of metal complexes (MCs) by green tea dye ligands improves environmental impact and reduces costs. The result of the current work establishes the production of metal complexes with huge amount and is an attempt from laboratory scales into commercial extent. This study investigates the application of green chemistry in producing PVA-based composites incorporating metal complexes, leading to enhanced light-matter interactions. The FTIR approach established that green tea dye (GTD) is enriched with ligands containing NH/OH, C = C, and C = O functional groups, which capture Pb²⁺ metal ions and form Pb-metal complexes. The FTIR indicates the peaks at 1404 and 1545 cm^-¹ associated with the symmetric and asymmetric stretching of the carboxylate group (COO^-) anion of the Pb(CH₃COO)₂ salt, while their disappearance in Pb-metal complexes (PbMC), establishing the coordination interactions among Pb²⁺ ions and polyphenol GTD ligands. It was found that integrating PVA solution with washed PbMC solution using a casting method is a novel green methodology for delivering PVA-based composites. The structural and optical properties of PVA: PbMC composites have been examined using XRD, FTIR, SEM and (UV-Vis) spectroscopy. The XRD pattern has confirmed that the semi-crystalline PVA film is transformed into an amorphous material in PVA/PbMC films. The FTIR spectra of the films demonstrated a significant interaction between polar PVA and PbMCs. The FESEM is a method employed to examine the morphological properties of materials, clarifying their surface structure, form, and texture. UV-Vis was used to study a wide range of optical parameters, including the dispersion energy (E_o and E_d), zero-frequency refractive index (n_o), oscillator wavelength, and strength (λ_o, S_o), which were determined using the Wemple-DiDomenico (WD) single oscillator model. An increase in Urbach tail (E_u) energy, linear and nonlinear refractive indices, and dielectric constant of polymer films, in addition to a reduction in energy gap E_g from (6.17 to 1.56 eV), was reported, with various models yielding matching outcomes. The absorption spectrum fitting (ASF) utilizing Tauc's models optically determined the physics of the type of transition electrons from the filled valence band (VB) to the empty conduction band (CB). The linear and nonlinear susceptibilities, χ⁽¹⁾, and χ⁽³⁾, were enhanced by PbMC doping. The acquired values qualify our synthesized materials for use in light-emitting diodes and image sensors. The film quality coefficient figure of merit (FOM), sheet resistance (R_s), and thermal emission (ε_Th) have been discovered as functions of wavelength. Examining the PVA/PbMC films suggested they may be suitable for optoelectronic devices, solar cell radiation monitoring, and several other applications.