Merging catalysis and supramolecular aggregation features of triptycene based Zn(salphen)s

Abstract

A series of trinuclear, triptycene-based metallosalphen complexes (M = Zn, Ni) have been prepared incorporating various peripheral substituents. The introduction of Zn metal centres into these triptycene based salphen ligands gives rise to cross-linking between different triptycene molecules through μ-phenoxo bridges between the Zn metal centres, and variation in the peripheral groups allows the control of the self-assembling properties as shown by UV-Vis titration data. The strong association of these trinuclear Zn₃ complexes under relatively apolar conditions has been exploited to recover the complex after its application as a catalyst in the cycloaddition of carbon dioxide to 1,2-epoxyhexane. The catalysis results and recycling studies show that the co-catalyst structure is important for efficient recovery of the binary system, demonstrating that reversible supramolecular aggregation may become a useful tool for recycling homogeneous catalysts.