Enabling an efficient light initiated one-pot synthesis of benzimidazoles over multifunctional 2D Pt/Ni-Fe-MOF nanosheets

Pt/Ni-Fe-MOF nanosheets (NSs), with small sized Pt nanoparticles of ca. 2 nm deposited on 2D Ni-Fe-MOF NSs of ca. 5.5 nm, were successfully fabricated and was used as a multifunctional catalyst for one-pot reaction between o-phenylenediamines and alcohols to produce benzimidazoles under visible light. By modulation on the reaction medium and the composition of the catalyst to regulate the individual reaction step involved, an optimum activity was achieved over 4 wt% Pt/Ni-Fe-MOF NSs in a mixed solvent of benzyl alcohol/toluene (v/v, 2/1), which showed a superior yield of 92.0 % to 2-phenylbenzimidazole. In comparison with its bulk counterpart, the superior activity observed over 2D Pt/Ni-Fe-MOF NSs can be attributed to a reduced recombination of the photogenerated charge carriers due to their short transportation path. This study first demonstrated that in addition to the different catalytic sites required, the individual reaction step involved in a one-pot tandem/cascade reaction can be regulated to enable an efficient whole reaction. Such a regulation of the rate of the individual reaction step can, to a certain degree, be achieved by modulation on the reaction medium and the component of the multifunctional catalyst. This study also provides the great potential of using 2D MOF for the construction of multifunctional catalysts for light initiated one-pot tandem/cascade reaction.