New heterogeneous Bi17V0.6Nb2.4-xPxO33 fluorite catalysts for the synthesis of benzimidazole derivatives

In this study, a new series of Bi₁₇V_0.6Nb_2.4-xP_xO₃₃ (0 ≤ x ≤ 1.2) solid solutions were synthesized via a solid-state route using Bi₂O₃, Nb₂O₅, V₂O₅, and (NH₄)₂HPO₄. X-ray diffraction confirmed their crystallization in a face-centered cubic structure (Fm3̅m), with lattice parameters decreasing progressively from 5.5146 to 5.5042 Å as phosphorus content increased. The materials were fully characterized using FTIR, SEM–EDX, and XRD techniques. These compounds were then evaluated as heterogeneous catalysts for the green synthesis of benzimidazole derivatives via the condensation of o-phenylenediamine with various aldehydes. The optimized protocol, employing 15 mol% of catalyst under ethanol reflux, delivered excellent yields (86–95%) in short reaction times. The catalysts showed high stability, easy recyclability over five cycles without loss of activity, and no detectable metal leaching. Green chemistry metrics—such as Atom Economy, E-factor, Reaction Mass Efficiency, and Carbon Efficiency—were calculated and demonstrated the environmental efficiency of the process. This work introduces a sustainable catalytic platform for benzimidazole synthesis and supports the broader integration of eco-friendly materials in organic transformations.