Hydrophobic/Hydrophilic Interplay in 1,2,4-Triazole- or Carboxylate-Based Molybdenum(VI) Oxide Hybrids: A Step Toward Development of Reaction-Induced Self-Separating Catalysts

2-(4H-1,2,4-triazol-4-yl)acetic acid (trglyH) and (dl)-4-methyl-2-(4H-1,2,4-triazol-4-yl)pentanoic acid (trleuH) were used as ligands for the development of MoO3 coordination hybrids for catalytic applications. Coordination polymers [Mo2O6(Htrgly)] . H2O (1) and [MoO3(trleuH)] . 0.5H(2)O (2) were prepared and structurally characterized. Compound 1 adopts a structure in which edge-sharing MoO6 octahedra are organized in a ribbon motif via mu(3)-O bridges. The Htrgly ligand exists as a zwitterion: -CO2- links two Mo-VI in a mu(2)-eta(1) : eta(1) mode, while positively charged triazolium is left uncoordinated. In 2, Mo atoms are joined in a chain through mu(2)-O. The more hydrophobic trleuH appears in a nonionized form and its [N-N] sites serve as a clamp for supporting the [-OMo(O)(2)-OMo(O)(2)(tr)(2)](n) sequence. The complexes were explored for liquid phase catalytic epoxidation of cis-cyclooctene, using H2O2 or tert-butylhydroperoxide as oxidants. The hybrids showed good catalytic activity, and 2 behaved as a reaction-induced self-separating catalyst for olefin epoxidation with H2O2, presenting advantages of homogeneous and heterogeneous catalysis.

Automated summary

In this study, MoO3 coordination hybrids were developed using specific ligands and utilized for liquid phase epoxidation reactions, demonstrating good catalytic activity and separation performance. The complexes synthesized showed promising applications in catalytic processes.