Synthesis and helical polymeric structure of a luminescent pendant-armed macrocyclic silver(I) complex with Ag-Ag interactions

An interesting 1D helical chain complex has been obtained with silver(I) nitrate and a tetrapyridyl pendant-armed macrocyclic ligand (L) in acetonitrile. The X-ray crystal structure of the complex, which has the formula ([Ag3L(NO3)](NO3)(2).8H(2)O)(infinity), presents silver-silver interactions in an infinite spiral chain structure that is unprecedented in such pyridyl macrocyclic complexes. The structure forms a large cavity or channel that contains the silver(I) ions and presents face-to-face pi,pi-stacking between the pyridyl rings. The complex shows fluorescence in the solid state and acetonitrile solution at room temperature.