Synthesis, Characterization, And Supramolecular System Of Asymmetric Double-layer Phthalocyanine Europium Complexes Of Crown Ether Substituted

Phthalocyanines (Pcs) are planar macrocycles related to porphyrins constituted by four isoindole units A great number of unique properties arise from this electronic delocalization, which makes these compounds applicable in different fields of materials science. Since the first sandwich-type phthalocyaninato rare earth complex was synthesized in 1936, all kinds of sandwich-type rare earth complexes were synthesized and researched deeply. This family of complex show extraordinary optic, electronic and magnetic properties. The huge potential as materials of novel molecular conductor, molecular semi-conductor, molecular magnet, gas-sensor, electrochemically generated multicolor response and electronic field directed luminescence etc, this arose people increasing fervor of research.Thus far, three synthetic pathways have been reported to prepare rare earth(III) double-decker complexes with two different kinds of phthalocyaninato ligands M(Pc')(Pc"). The first method involves a mixed cyclization of the two corresponding phthalonitrile precursors in the presence of a metal salt, which is not practically useful because of the difficulties in separating the statistical mixtures of differently substituted bis(phthalocyaninato) rare earth complexes. The second pathway involves the treatment of M(acac)₃.nH₂O with two different phthalocyaninates H₂/Li₂(Pc') and H₂/Li₂(Pc"). As expected, this procedure leads to a substantial amount of homoleptic double-deckers M(Pc')₂ and M(Pc")₂ as the side-products. The third route employs the half-sandwich complexes M(Pc')(acac) as the template, which induces cyclic tetramerization of the other phthalonitrile in the presence of DBU.In this paper, we report the synthesis, separation, and molecular structure of the series of heteroleptic bis(phthalocyaninato) europium complexes, Eu(Pc)[Pc(15C5)] (2), Eu(Pc)[Pc(adj-15C5)₂] (3), Eu(Pc)[Pc(opp-15C5)₂] (4), Eu(Pc)[Pc(15C5)₃] (5), and Eu(Pc)[Pc(15C5)₄] (6), with one, two, three, and four 15-crwon-5 ether voids attached onto one of the two phthalocyanine ligands of the bis(phthalocyaninato) double-decker complexes. All the newly prepared bis(phthalocyaninto) europium complexes obtained after column chromatographic purification and recrystallization gave essentially satisfactory elemental analysisresults. Their sandwich nature was further unambiguously deduced from spectroscopic methods including mass, UV-vis, near IR, IR, and especially the single crystal molecular structure for the compound 6. The molecular ion (M)+ in which distinct isotopic distribution can be observed was obtained in the MALDI-TOF mass spectrum. The good correspondence of the relative abundance of the isotopic clusters with the simulated spectra unambiguously demonstrates the identity of these compounds.