Synthesis and Characterization of Rare Earth Corrole–Phthalocyanine
Heteroleptic Triple-Decker Complexes
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Abstract
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 M<sub>2</sub>[Pc(OC<sub>4</sub>H<sub>9</sub>)<sub>8</sub>]<sub>2</sub>[Cor(ClPh)<sub>3</sub>], 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 OC<sub>4</sub>H<sub>9</sub> Pc
substituents was obtained in too low a yield to characterize, but
for the purpose of comparison, Y<sub>2</sub>[Pc(OC<sub>5</sub>H<sub>11</sub>)<sub>8</sub>]<sub>2</sub>[Cor(ClPh)<sub>3</sub>] was
synthesized and characterized in a similar manner. The molecular structure
of Eu<sub>2</sub>[Pc(OC<sub>4</sub>H<sub>9</sub>)<sub>8</sub>]<sub>2</sub>[Cor(ClPh)<sub>3</sub>] 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 <i>E</i><sub>1/2</sub> values being linearly related to the ionic radius of the
central ions. The energy (<i>E</i>) 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
