Synthesis and Characterization of Rare Earth Corrole–Phthalocyanine Heteroleptic Triple-Decker Complexes

We recently reported the first example of a europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles and have now extended the synthetic method to prepare a series of rare earth corrole–phthalocyanine heteroleptic triple-decker complexes, which are characterized by spectroscopic and electrochemical methods. The examined complexes are represented as M2[Pc­(OC4H9)8]2[Cor­(ClPh)3], where Pc = phthalocyanine, Cor = corrole, and M is Pr­(III), Nd­(III), Sm­(III), Eu­(III), Gd­(III), or Tb­(III). The Y­(III) derivative with OC4H9 Pc substituents was obtained in too low a yield to characterize, but for the purpose of comparison, Y2[Pc­(OC5H11)8]2­[Cor­(ClPh)3] was synthesized and characterized in a similar manner. The molecular structure of Eu2[Pc­(OC4H9)8]2­[Cor­(ClPh)3] was determined by single-crystal X-ray diffraction and showed the corrole to be the central macrocycle of the triple-decker unit with a phthalocyanine on each end. Each triple-decker complex undergoes up to eight reversible or quasireversible one-electron oxidations and reductions with E1/2 values being linearly related to the ionic radius of the central ions. The energy (E) of the main Q-band is also linearly related to the radius of the metal. Comparisons are made between the physicochemical properties of the newly synthesized mixed corrole–phthalocyanine complexes and previously characterized double- and triple-decker derivatives with phthalocyanine and/or porphyrin macrocycles.