Hexagonal Microparticles from Hierarchical Self-Organization of Chiral Trigonal Pd3L6 Macrotetracycles

Ondřej Jurček, Nonappa, Elina Kalenius, Pia Jurček, Juha M. Linnanto, Rakesh Puttreddy, Hennie Valkenier, Nikolay Houbenov, Michal Babiak, Miroslav Peterek, Anthony P. Davis, Radek Marek, Kari Rissanen

Cell Rep. Phys. Sci. 2021, 2, 100303


Construction of structurally complex architectures using inherently chiral, asymmetric, or multi-heterotopic ligands is a major challenge in metallosupramolecular chemistry. Moreover, the hierarchical self-organization of such complexes is unique. Here, we introduce a water-soluble, facially amphiphilic, amphoteric, chiral, asymmetric, and hetero-tritopic ligand derived from natural bile acid, ursodeoxycholic acid. We show that via the supramolecular trans- metalation reaction, using nitrates of Cu(II) or Fe(III), and subsequently Pd(II), a superchiral Pd3L6 complex can be obtained. Even though several possible constitutional isomers of Pd3L6 could be formed, because of the ligand asymmetry and relative flexibility of carbamate-pyridyl moieties attached to the steroid scaffold, only a single product with C3 rotational symmetry was obtained. Finally, we demonstrate that these amphiphilic complexes can self-organize into hexagonal microparticles in aqueous media. This finding may lead to the development of novel self-assembled metal-organic functional materials made of natural, abundant, and relatively inexpensive steroidal compounds.