The double-decker lutetium(III) phthalocyanine, Lu[(RS)4Pc]2, where R = C12H25, was synthesized and electrochemically characterized under several solution conditions. The neutral complex undergoes a single reversible one-electron oxidation and up to four reversible one-electron reductions in nonaqueous solutions of CH2Cl2 or benzonitrile containing 0.1 M tetra-n-butylammonium perchlorate (TBAP), while one oxidation and five reductions are seen in aqueous 0.5 M KCl for a gel-like cast film membrane of Lu[(RS)4Pc]2 in a tetraoctylphosphonium bromide (4C8P+Br-) matrix at a basal plane pyrolytic graphite electrode. The half-wave potentials for reduction of Lu[(RS)4Pc]2 in CH2Cl2, 0.1 M TBAP are located at E 1/2 = 0.04, −1.03, −1.36 and −1.73 V, while the single oxidation is located at E 1/2 = 0.43 V vs SCE. These potentials, when measured vs Fc/Fc+, are negatively shifted by 0.20−0.46 V from the E 1/2 values obtained in the 0.5 M KCl solution where the electrogenerated anions of the double-decker complex are stabilized by the cations of the 4C8P+Br- matrix and five reductions are seen at E 1/2 = 0.29, −0.66, −0.94, −1.22, and −1.41 V vs SCE. The fifth reduction has been theoretically predicted but had never before been observed for any double-decker lutetium(III) phthalocyanine or related complex. A cast film of Lu[(RS)4Pc]2 displays only one oxidation in the 0.5 M KCl solution (at E 1/2 = 0.78 V vs SCE), and no reductions at all are seen in the absence of a matrix. An almost identical oxidation potential of E 1/2 = 0.80 V is seen for oxidation of Lu[(RS)4Pc]2 in KCl when dissolved in the cationic matrix. These half-wave potentials for oxidation in the cationic film, when measured vs Fc/Fc+, are thus more positive by more than 0.27−0.32 V than E 1/2 values measured in CH2Cl2 or PhCN and this is consistent with a decreased degree of solvent or anion binding to {Lu[(RS)4Pc]2}+ in the 4C8P+Br- matrix, as compared to what is observed in solution.

The double-decker lutetium(III) phthalocyanine [( C 6 H 13 S )8 Pc ]2 Lu was investigated by electrochemical and spectroelectrochemical methods and comparisons made to previously investigated [( C 12 H 25 S )4 Pc ]2 Lu and ( Pc )2 Lu under the some experimental conditions. All three compounds undergo a single reversible one-electron oxidation and up to four reversible one-electron reductions in CH 2 Cl 2 containing 0.1 M tetra-n-butylammonium perchlorate (TBAP). The octa- and tetra substituted phthalocyanine derivatives exhibit one oxidation and three or four reductions in solution while five reductions can be detected for the two compounds in a gel-like cast film membrane of tetraoctylphosphonium bromide (4 C 8 P + Br −) at a basal plane pyrolytic graphite electrode which was immersed in aqueous 0.5 M KCl . The half-wave potentials of these SR substituted complexes in CH 2 Cl 2 are negatively shifted by 210-490 mV from E1/2 values for the same compounds in the aqueous 4 C 8P+ Br − matrix and five reductions of these compounds are observed under the latter experimental conditions. The UV-visible spectra of the compounds were measured in five different oxidation states and ESR spectra were also characterized for the neutral and doubly reduced complexes. As was expected, [( Pc )2 Lu ]−,{[( C 6 H 13 S )8 Pc ]2 Lu }− and {[( C 12 H 25 S )4 Pc ]2 Lu }− are ESR silent while electrogenerated [( Pc )2 Lu ]2−, {[( C 6 H 13 S )8 Pc ]2 Lu }2− and {[( C 12 H 25 S )4 Pc ]2 Lu }2− show broad strong signals at g = 2.0046, 2.0041 and 2.0034 with linewidths of 13.9, 16.1 and 12.9, respectively. These signals are indicative of organic free radicals where the unpaired electrons of the dianion are delocalized over two macrocycles.