Synthesis, spectral properties and supramolecular dimerisation of heteroleptic triple-decker phthalocyaninato complexes with one outer crown-substituted ligand

Four complexes – [(15C5)4Pc]M(Pc)M(Pc), (Pc2− – phthalocyaninato-dianion, [(15C5)4Pc]2− – 2,3,9,10,16,17,24,25-tetrakis(15-crown-5)phthalocyaninato-dianion, M = Sm, Dy, Tm, Y) were obtained via the reaction of M(Pc)2, H2[(15C5)4Pc] and M(acac)3. The influence of the stability of starting M(Pc)2 on the yields of target compounds was investigated. Increasing the stability of M(Pc)2 leads to higher yields of [(15C5)4Pc]M(Pc)M(Pc) and lower yields of scrambling products. All complexes were characterized by 1H NMR, UV–Vis and FT-IR spectroscopy as well as MALDI TOF mass-spectrometry. The analysis of 1H NMR spectra was performed in terms of lanthanide-induced shifts. Cation-induced dimerisation was studied by means of spectrophotometric titration. Supramolecular dimers {2[(15C5)4Pc]M(Pc)M(Pc) · 4K+} are the largest discrete cofacial supramolecular assemblies built of phthalocyanine building blocks reported up-to-date. The observed increase of the intermolecular excitonic interaction between building blocks with the increase of REE(III) size is tentatively explained in terms of metal-size dependent deformation of phthalocyanine ligands in sandwich complexes.