A minimal cage of a diamond twin with chirality.

A network of tetrahedral vertices can fill three-dimensional (3D) spaces in a beautiful and isotropic manner, which is found as diamonds with sp 3 -hybridized carbon atoms. Although a network of trigonal vertices (i.e., another form of carbon atoms with sp 2 -hybridization) naturally results in a lower-dimensional two-dimensional network of graphenes, an isotropic 3D arrangement of trigonal vertices has been of theoretical and mathematical interest, which has materialized as a proposal of a "diamond twin." We herein report the synthesis and optical resolution of a minimal cage of a chiral diamond-twin network. With triangular phenine units at 14 vertices, triply fused decagonal rings were assembled by forming 15 biaryl edges via coupling. A unique chirality of the network has been disclosed with the minimal cage, which may stimulate explorations of chiral carbonaceous materials.