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 (5,3 4) 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 (5,3 4) 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.

Distortional Supramolecular Isomers of Polyrotaxane Coordination Polymers: Photoreactivity and Sensing of Nitro Compounds

“…Such conformational differences in bpeb ligand has been observed before in a guest‐triggered reversible SCSC structural conversion between supramolecular isomers with unusual isomers of paddle‐wheel building blocks 13. Recently, an example for supramolecular isomerism in pseudo‐polyrotaxane system containing a luminescent cuprous cyanide was reported by Zhang et al 14. To the best of our knowledge, this is an unusual example of supramolecular isomerism in polyrotaxane structures by conformational differences of bpeb spacer ligand as well as relative distances between the bpeb ligands in the entangled structures.…”

Two-Dimensional Metal-Organic Framework Materials: Synthesis, Structures, Properties and Applications

“…Supramolecular 3D polypseudorotaxane isomers of [Cu 2 (pz)­(CN) 2 ]·[CuCN]. Reproduced with permission from ref . Copyright 2012 American Chemical Chemistry.…”

Crystal structure of catena-poly[[[(2-ethoxypyrazine-κN)copper(I)]-di-μ2-cyanido] [copper(I)-μ2-cyanido]]

“…Mixed-valence Cu I /Cu II coordination complexes with cyanide and amine ligands having different supramolecular architectures and their luminescence properties have also been reported (Grifasi et al, 2016). To improve the design of copper cyanide coordination polymers, as well as to investigate its influence on the resulting luminescence and other properties, different types of co-ligands were used, in particular, N-donor bridging or chelating ligands, such as 1,10-phenanthroline, 4,4 0 -bipyridine (Su et al, 2011), pyridines with methyl, ethyl, methoxy and other substituents (Dembo et al, 2010), and pyrazine (Qin et al, 2012;Chesnut et al, 2001) Fig. 1 shows a fragment of the title compound, which is a polymeric copper complex with different coordination envir-onments of the two crystallographically independent Cu I ions.…”