Base-Mediated Scalable Synthesis of Polybenzothiazoles: Fused-Heterocycle-Engineered Recovery of Precious Metals.

Sulfur-containing fused heterocyclic polybenzothiazoles are promising materials with advanced functionalities, yet their synthesis has long been constrained by substrate limitations and scalability challenges. Here, a base-mediated multicomponent polymerization strategy using readily available elemental sulfur, aromatic diamines, and aromatic dialdehydes is developed to synthesize unprecedented polybenzothiazoles with scalability. By efficient alkaline activation of substrates through nucleophilic sulfurization-cyclization cascades, this method enables economically viable kilogram-scale production in a one-pot process with high yields (73-98%) and monomer universality, including previously incompatible electron-deficient aromatic amines. The resulting polybenzothiazoles unlock their long-overlooked potential in precious metal recovery, demonstrating selective, rapid, and efficient extraction (>99%) of gold (Au), palladium (Pd), and platinum (Pt) from ultra-trace concentrations (1 ppb) to complex matrices including surface water, e-waste, and spent catalyst leachates. Mechanistic studies reveal that the synergistic nitrogen (N)/sulfur (S) participation and π-conjugation in their fused heterocycles govern metal coordination selectivity and redox stability. This work establishes a practical yet versatile platform to advance polybenzothiazoles from synthesis to resource utilization, highlighting their transformative role in addressing critical challenges through adaptive material design and precious metal recovery.