Effect of tetrachloro cadmium (II)/cobalt (II) ions modulation on organic-macrocyclic adaptive assembly based on cucurbit[6]uril and p-nitrophenol

Abstract

Adaptive pore channels provide many possibilities for constructing functional supramolecular assemblies, making macrocyclic-based assemblies available for a variety of functions. To investigate the effect of ions modulation on the structure and properties of organic-macrocyclic adaptive assemblies, two supramolecular assemblies based on cucurbit[6]uril (Q[6]) and p-nitrophenol (PNP) are constructed through the outer-surface interactions of cucurbit[n]urils (Q[n]s): assembly 1 (Q[6]-PNP) and assembly 2 (Q[6]-PNP-[CdCl4]2−-[CoCl4]2−). The structural characteristics and the difference in the ability of the two assemblies to capture PNP molecules are investigated by X-ray crystallography, UV–vis spectroscopy, etc. It is found that after [CdCl4]2−, [CoCl4]2− are added as structure-directing agents, many honeycomb-like hexagonal pores are formed in assembly 2, but its ability to capture PNP molecules is only one-third of that of assembly 1. This indicates that ions modulation may reduce the ability of macromolecules to capture organic molecules, but the assembly 2 modulated by tetrachloro cadmium (II) /cobalt (II) ions has many honeycomb-like pores, which also provides new insights for the construction of more supramolecular assemblies with functionality based on Q[n]s.