Calix[4]pyrrole; a potential dye for dye sensitised solar cells

A cation receptor, the calix[4]pyrrole acetamide (CPA), bearing a strong cation recognition site, has been synthesized and characterized by standard spectroscopic means and microanalysis. In CH3CN, this receptor binds lanthanides Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Lu³⁺ and Sc³⁺ cations. When exposed to these cations in the presence of trifluoromethanesulfonate as counterions it forms stable 1:2 complexes. In contrast to what has been reported about calix[4]pyrroles, that they interact strongly with anions, and this occurs through the pyrrolic N-H. The cation recognition in this receptor takes place within the receptor cavity in both sites (NH cavity of the parent calix[4]pyrrole, CP and the acetamide lower cavity), as inferred from ¹H NMR spectroscopic studies.