Photocatalytic Oxidative Coupling of Benzyl Alcohol and Benzylamine for Imine Synthesis Using Immobilized Cs₃Bi₂Br₉ Perovskite

The oxidative cross-coupling of benzyl alcohol (BA) and benzylamine (BZA) is employed for the production of the corresponding imine, N-benzylidenebenzylamine (BZI), under visible light irradiation (light-emitting diodes (LE with λ_max = 417 nm) and mild reaction conditions. The cesium bismuth halide perovskites (Cs₂Bi₃Br₉, CBB) are synthesized by a one-step solution process as a sustainable alternative for the widely used Pb-halide perovskites. The CBB photocatalyst is immobilized on a polyethylene terephthalate (PET) structure designed explicitly for three-dimensional (3D) printing to operate in both batch and continuous modes to overcome the need for a final catalyst separation step. The complete conversion of BZA and BA is achieved after 1 h, yielding 70% of BZI in basic medium operating in batch mode. Comparable results are found between the suspended and immobilized catalysts for imine production. Additionally, continuous production of BZI is successfully achieved using immobilized CBB, with a maximum yield of 0.35 mm of BZI after a 2 h reaction. The supported CBB perovskites demonstrate high stability after multiple uses. Finally, a comprehensive photocatalytic pathway for cross-coupling BZA with BA is proposed.