Allosteric and Electrostatic Reprogramming of a Ditopic Ligand

A potentially tetradentate pyridyl–thiazole ligand chain and an additional “external” crown ether binding site connect the two halves of a new ditopic ligand. The pyridyl‐thiazole binding sites can be changed or “reprogrammed” by the addition of Ba2+: In the presence of Hg2+ and Na+ the ligand L1 forms a dinuclear double helicate ([Hg2(L1)2Na2]6+), whereas in the presence of Hg2+ and Ba2+ a mononuclear species is formed ([Hg(L1)Ba]4+).