Fig. 11.

Inclusion complex of CLR01 and Zn²⁺. P atoms are indicated in tan, O in red, C in cyan, and H in white. The structure of the complex was calculated with the DFTB3-D3H5 method (Řezáč, 2017) implemented in the DFTB+ program (Hourahine et al., 2020) in implicit solvent (Onufriev and Case, 2019). The optimized structure resembles the experimentally determined single-crystal structure of a Cs⁺ atom with a MT containing one OH group and one O-CH₂-CO₂^- group at the central hydroquinone ring (Klärner et al., 2000). π-cation interactions between four of the five aromatic MT rings and the metal cation, as well as the ionic interactions between Zn²⁺ and both OP(OH)O₂^- side chains, lead to the binding of the metal cation inside the MT cavity.