Anomalous electronic absorption spectra of lanthanide diphtalo- and dinaphtalocyanines

Lanthanide (Ln) complexes of diphtalo-(Pc2) and 2,3-dinaphtalocyanines (Nc2) are sandwich-like stable free radicals of practical interest. In contrast to common metal complexes their electronic absorption spectra both in organic solvents and sublimed films have two relatively intensive bands in NIR region (ε ∼ 104M-1cm-1), caused by intermolecular charge transfer. For series of octa-4-tert-butyl-substituted Pc2Ln large bathochromic shift of bands with increased lanthanide ionic radius from 1390 nm for Lu to 2160 nm for La is observed. Linear correlation has been established between wave number of longwave bands maximum and Ln ionic radius value. In the spectra of Nc2Ln and their octa-6-tert-butyl-substituted analogues with extended conjugation bathochromic a shift of bands in visible (100-120 nm) and IR (∼ 200 nm) region has been detected compared to corresponding Pc2Ln bands. (author)