Bloch, Witold M.Horiuchi, ShinnosukeHolstein, Julian J.Drechsler, ChristophWuttke, AxelHiller, WolfMata, Ricardo A.Clever, Guido H.2023-02-012023-02-012023-01-19http://hdl.handle.net/2003/4122010.17877/DE290R-23064Helicity is an archetypal structural motif of many biological systems and provides a basis for molecular recognition in DNA. Whilst artificial supramolecular hosts are often helical, the relationship between helicity and guest encapsulation is not well understood. We report a detailed study on a significantly coiled-up Pd2L4 metallohelicate with an unusually wide azimuthal angle (∼176°). Through a combination of NMR spectroscopy, single-crystal X-ray diffraction, trapped ion mobility mass spectrometry and isothermal titration calorimetry we show that the coiled-up cage exhibits extremely tight anion binding (K of up to 106 M−1) by virtue of a pronounced oblate/prolate cavity expansion, whereby the Pd–Pd separation decreases for mono-anionic guests of increasing size. Electronic structure calculations point toward strong dispersion forces contributing to these host–guest interactions. In the absence of a suitable guest, the helical cage exists in equilibrium with a well-defined mesocate isomer that possesses a distinct cavity environment afforded by a doubled Pd–Pd separation distance.enhttps://creativecommons.org/licenses/by-nc/3.0/Supramolecular chemistryHelicitySupramolecular hostMetallohelicateAnion binding540article (journal)