An elegant approach for the synthesis of multisubstituted imidazole FeCl/SiO catalyzed activation of acetals: a photophysical study of an imidazole-carbazole hybrid

• Published in: RSC advances 2024-10, Vol.14 (45), p.33512-33523
• Main Authors: Das, Barnali, Bhattacharyya, Arghyadeep, Paul, Bhaswati, Natarajan, Ramalingam, Majumdar, Swapan
• Format: Article
• ISSN: 2046-2069
• DOI: 10.1039/d4ra06436d

A simple and solvent-free catalytic system was developed for the direct conversion of multisubstituted imidazoles through the reaction of acetals and benzils with ammonium acetate/amines as the source of nitrogen. The reaction occurred under mild and benign conditions using FeCl 3 /SiO 2 as a heterogeneous catalyst without the requirement of any toxic organic solvents. The easy preparation and recyclability of the catalyst allows the reaction to be simple and highly efficient, resulting in very good yields of imidazoles. Novel imidazole-carbazole hybrid compounds were also synthesised by adopting the present methodology. Single crystal X-ray diffraction study indicated the presence of a CH π supramolecular interaction that renders effective molecular packing in the solid state. The steady-state and spectro-dynamic behaviours of these hybrid molecules were investigated, and it was revealed that a solvent-dependent excimer-coupled ICT phenomenon guided excited state photophysics. Very unusual excimer lifetime was noticed in the solid state of this bis-heterocyclic compound owing to the stacking of molecules via CH π interaction, as evident from the X-ray studies. Here, synthesis of substituted imidazoles from benzil, protected carbonyl and NH 4 OAc/primary amine in the presence of a FeCl 3 /SiO 2 catalyst is reported. The photophysical property of the synthesized imidazole-carbazole hybrid is also investigated.