Electrochemical and spectroscopic investigation of neutral, oxidized and reduced double-decker lutetium(III) phthalocyanines

Abstract

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.

Use of the electrochromic behaviour of lanthanide phthalocyanine films for nicotinamide adenine dinucleotide detection

“…The reduced anionic forms of double-decker lutetium( III ) phthalocyanines are believed to be associated with mono-and divalent alkali metal cations and this association also occurred with the cations in our 4C 8 P C Br K matrix, thus leading to a larger stabilization of the electroreduced forms of phthalocyanine in the film. A similar result was also obtained for the lutetium(III ) analogue of [(C 6 H 13 S) 8 Pc] 2 Dy investigated in this work ( Yilmaz et al 2003).…”

“…The UV-visible spectra of [(C 6 H 13 S) 8 Pc] 2 Dy films in neutral and oxidized forms are presented in figure 3. The evolution of the spectral change upon the first oxidation is similar to that for the [(C 6 H 13 S) 8 Pc] 2 Lu analogue ( Yilmaz et al 2003). The colour of the film was observed to change from brown (neutral form) to green.…”

A3B‐Type Phthalocyanine‐Based Homoleptic Lanthanide(III) Double‐Decker π‐Radical Complexes Bearing Functional Hydroxy Groups: Synthetic Approach, Spectral Properties and Electrochemical Study

“…UV/Vis spectral changes for complex 2a ( HO,Bu Pc 2 Eu) during controlled potential electrolysis at +0.15 and -0.85 V (Figure 6) reflect the transformation of the neutral double-decker phthalocyanine to the one-electron-oxidized and -reduced forms, [15,17] respectively. The data for 1a ( BnO,Bu Pc 2 Eu) obtained under the same conditions gave identical band positions for all redox states (Table 4).…”

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Pc = 2-benzyloxy-9,10,16,17,23,24-hexa-n- Pc = 9,10,16,17,23,24-hexa-nbutyl-2-hydroxyphthalocyaninate) (2a, 2b), which are prom-

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Synthesis, Spectroscopic and Electrochemical Investigations of Two vic‐Dioximes and Their Mononuclear Ni(II), Cu(II) and Co(II) Metal Complexes Containing Morpholine Group

“…It is known from the literature that the introduction of electron-donating groups to the macrocylic cores is expected to lead to an increase in the electron density of the central metal atom, thereby making a complex easier to oxidise and harder to reduce. [32][33][34][35][36] So the cathodic electrode potential negatively shifted for the reduction of the oxime moity could be expected due to the existence of electron-donating groups attached to the main oxime unit. But the more positive anodic peak potentials based on the ligand may be caused by the culombing interaction with the electrogenerated cationic species and solvent.…”