Incarceration of one or two phosphate or arsenate species within nanojars, capped nanojars and nanohelicages: helical chirality from two closely-spaced, head-to-head PO₄³⁻or AsO₄³⁻ions

Unprecedentedly strong binding of HXO4(2-) and XO4(3-) ions (X = P or As) within self-assembled nanohosts with protein-like anion binding cavities is reported. One of the nanohosts binds two XO4(3-) ions at an unusually short distance, resulting in helical chirality.