Synthesis, Spectroscopic Characterization, and Photostability Studies of a New Ligand Derivative of 4-Bromobenzaldehyde and its Metal Complexes

The new Schiff base ligand (LB) was synthesized by reacting precursor (P) with 4-bromobenzaldehyde. This ligand formed three new complexes: [Pd(LB)(H2O)2]Cl2 (square planar) and [M(LB)(H2O)2Cl2].mCl2 (octahedral), where m=0 for Co+2 and 1 for Pt+4, upon reaction with the respective metal ions. Characterization of the ligand (LB) and its metal complexes involved various techniques including 1H- and 13C-NMR, FT-IR, UV-Vis spectroscopy, magnetic susceptibility measurements, CHNS analysis, and molar conductivity. The photo-stabilization of polymers aims to mitigate or delay photochemical degradation during irradiation of plastic materials like polyvinyl chloride (PVC) in tetrahydrofuran (THF). Prepared compounds (ligand LB and its metal complexes) were incorporated into PVC at 0.5% w/w concentration. Under irradiation with light at λ = 380–250 nm and intensity of 7.75×10-9 ein dm-3 s-1 at 25°C, the photo-stabilization efficacy of these additives was evaluated by monitoring changes in carbonyl, polyene, and hydroxyl indices over time, using weight loss as a measure. Observations showed that ICO, IOH, and IPO index values increased with irradiation time, varying depending on the additive type. Surface morphology of the films was also studied over time. This application holds significance for environmental conservation by addressing concerns related to plastic consumption reduction.