Reconstruction of a (6,3) Brick Wall Sheet Giving an Unprecedented Shubnikov-type (5,³₄) Sheet in Luminescent Cuprous Cyanide Supramolecular Isomers of Pseudo-polyrotaxane

Abstract

Reactions of CuCl2, K3[Fe(CN)6]/K4[Fe(CN)6], and pyrazine (pyz) in water solution at 160 °C/170 °C for 6 days led to two luminescent supramolecular isomers with stoichiometry [Cu2(pyz)(CN)2]·[CuCN] (1 and 2), which show 3D pseudopolyrotaxane structures with 1D [Cu(CN)]∞ chains penetrating 2D [Cu2(pyz)(CN)2] sheets. Isomer 1 contains linear, trigonal, and tetrahedral Cu(I) atoms, which are linked by pyz and cyanide groups into unprecedented (3,4)-connected Shubnikov-type (5,34) sheets, and these sheets are penetrated by [Cu(CN)]∞ chains via unsupported CuI–CuI interactions. In contrast, the [Cu2(pyz)(CN)2] sheets in isomer 2 can be viewed as a classical (6,3)-topological brick wall layer, which are also penetrated by [Cu(CN)]∞ chains in the absence of cuprophilicity. Schematically, the brick wall and Shubnikov-type (5,34) nets can be formed via arrangement of brick rows in ABAB and ABBA modes, respectively. It is worth noting that cyanide sources played a crucial role in the formation of supramolecular isomers. 1 and 2 show strong photoluminescence related to the various local coordination geometries of copper atoms and weak cuprophilic interactions.