News from Nanotechjapan


Synthesis of Spherical Metal Polyhedron Guided by a Theorem in Geometry---Self-assembly of chemical compound with large internal space to enclose proteins---

 The University of Tokyo and Japan Science and Technology Agency (JST) released a news on July 8, 2016 to inform that Professor Makoto Fujita of the university and his colleagues have succeeded in synthesizing an M30L60 molecular icosidodecahedron,  consisting of ∼100 components: 30 Metal ions and 60 Ligands,  under the guidance of a theorem in geometry. Details were published in Chem*. 

 Self-assembly is invaluable in the construction of giant molecular structures via a bottom-up approach. Inspired by the elegant structures of virus capsids, the research group has been tackling self-assembly of divalent Pd2+ ions (M) and ditopic pyridyl ligands with a bend angle (L) to make giant spherical metal complexes with the composition MnL2n. Because Pd2+ has four coordination sites with square planar geometry, only five structures are theoretically available for self-assembled MnL2n polyhedrons with n=6, 12, 24, 30, and 60. The group has already succeeded in preparing the composites up to 24, and the present challenge was to make M30L60

 Based on the kinetics on self-assembly and geometry analysis, they found that M30L60 has to adopt dodecahedral symmetry that contains pentagon faces, in contrast to cubic symmetry for n = 6, 12, or 24. Thus, flex-tuned ligand is designed rationally to obtain the M30L60 icosidodecahedral self-assembled metal complex. Single-crystal X-ray structural analysis confirmed that polyhedron consists of precisely 90 subcomponents, and showed its diameter to reach 8.2 nm. The interior space of the molecular complex is large enough (157 nm3) to enclose biological macromolecules such as proteins.

* Daishi Fujita, Yoshihiro Ueda, Sota Sato, Hiroyuki Yokoyama, Nobuhiro Mizuno, Takashi Kumasaka, and Makoto Fujita, "Self-Assembly of M30L60 Icosidodecahedron", Chem, Vol. 1, No. 1, pp. 91-101 (2016), doi: 10.1016/j.chempr.2016.06.007; Published July 7, 2016