Anion-driven conformation control and enhanced sulfate binding utilising aryl linked salicylaldoxime dicopper helicates

Abstract

The synthesis and spectroscopic analysis of both “metal-only” and anion encapsulated dicopper(II) double helicates utilising a new 1,4-aryl spacer is described. X-Ray crystallographic analysis of the complexes reveal that the aromatic spacer increases rigidity in the complex, yet the complexes are still able to undergo a dramatic “coiling up” to bind anions. Spectroscopic analysis has shown a clear enhancement in the binding strength of SO₄²⁻ over the non-coordinating anions ClO₄⁻, NO₃⁻ and Br⁻ which has been attributed to a combination of enhanced rigidity in the complex and an increased electrostatic interaction between the complex and the dianion.