Influencing the Self-Sorting Behavior of [2.2]Paracyclophane-Based Ligands by Introducing Isostructural Binding...

Two isostructural ligands with either nitrile (L^nit ) or isonitrile (L^iso ) moieties directly connected to a [2.2]paracyclophane backbone with pseudo-meta substitution pattern have been synthesized. The ligand itself (L^nit ) or its precursors (L^iso ) were resolved by HPLC on a chiral stationary phase and the absolute configuration of the isolated enantiomers was assigned by XRD analysis and/or by comparison of quantum-chemical simulated and experimental electronic circular dichroism (ECD) spectra. Surprisingly, the resulting metallosupramolecular aggregates formed in solution upon coordination of [(dppp)Pd(OTf)₂ ] differ in their composition: whereas L^nit forms dinuclear complexes, L^iso exclusively forms trinuclear ones. Furthermore, they also differ in their chiral self-sorting behavior as (rac)-L^iso undergoes exclusive social self-sorting leading to a heterochiral assembly, whereas (rac)-L^iso shows a twofold preference for the formation of homochiral complexes in a narcissistic self-sorting manner as proven by ESI mass spectrometry and NMR spectroscopy. Interestingly, upon crystallization, these discrete aggregates undergo structural transformation to coordination polymers, as evidenced by single-crystal X-ray diffraction.