Coordinative helix–helix association of heteroleptic metallosupramolecular helicates

Abstract

The effective incorporation of well-defined coordination spheres, multiple types of ligands (heteroleptic), and specific assembly modes in a given structure enables the fabrication of simplified coordinative supramolecular bio-mimics. Herein, we report the fabrication of a unique racemic macrocycle via association of metallosupramolecular helicates. A nickel ({Ni₄}) cluster-based supramolecular helicate, [Ni₈(PDA)₆(CDBA)₃(DMF)₂(H₂O)₄] (1) (PDA = 2,6-pyridinedicarboxylate, CDBA = 4,4′-carbonyldibenzoate, DMF = dimethylformamide), is successfully synthesized and fully characterized. Dimerization of right (P-) and left (M-) handed helicates of 1via the coordination of metalloligands, [Ni(PDA₂)]²⁻ affords {[Ni₈(PDA)₆(CDBA)₃(DMF)₄–Ni(PDA)₂]₂} (2), which can be a representative model of the coordinative helix–helix association of heteroleptic helicates. The solid-state structures of 1 and 2 show high and selective CO₂ uptake properties.