Ammonia-Doped Polyaniline–Graphitic Carbon Nitride Nanocomposite as a Heterogeneous Green Catalyst for Synthesis of Indole-Substituted 4H-Chromenes

[Image: see text] A nanocomposite of polyaniline with graphitic carbon nitride (GCN) nanosheets has been synthesized by a facile oxidative polymerization of an aniline monomer and GCN to demonstrate its potential to catalyze the synthesis of various indole-substituted 4H-chromenes. The synthesized nanocomposite was thoroughly characterized using different spectroscopic techniques to confirm the morphology and composition. Subsequently, the fabricated nanocomposite was used as a heterogeneous catalyst to synthesize several bioactive indole-substituted 4H-chromenes in an aqueous medium. Organic transformation under benign and environmentally sustainable conditions is of paramount importance in the view of growing environmental pollution. Water is the universal Green solvent and has been a preferred choice of nature to perform various reactions. The catalyst developed in this work showed very good recyclability and adaptability for the synthesis of various medicinally significant indole-substituted 4H-chromenes. This multicomponent reaction imparts very high atom economy (94%) and low environmental factor (0.13).