Recognition Properties and Self-assembly of Planar [M(2-pyridyl-1,2,3-triazole) ₂ ] ²⁺ Metallo-ligands

Molecular recognition continues to be an area of keen interest for supramolecular chemists. The investigated [M(L) ₂ ] ²⁺ metallo-ligands (M=Pd ^II , Pt ^II , L=2-(1-(pyridine-4-methyl)-1 H-1,2,3-triazol-4-yl)pyridine) form a planar cationic panel with vacant pyridyl binding sites. They interact with planar neutral aromatic guests through π–π and/or metallophilic interactions. In some cases, the metallo-ligands also interacted in the solid state with Ag ^I either through coordination to the pendant pyridyl arms, or through metal–metal interactions, forming coordination polymers. We have therefore developed a system that reliably recognises a planar electron-rich guest in solution and in the solid state, and shows the potential to link the resultant host–guest adducts into extended solid-state structures. The facile synthesis and ready functionalisation of 2-pyridyl-1,2,3-triazole ligands through copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) “click” chemistry should allow for ready tuning of the electronic properties of adducts formed from these systems.