Raman spectroscopic characteristics of phthalocyanine in mixed [5-(4-hydroxyphenyl)-10,15,20-tris(4-octyloxyphenyl) porphyrinato]-(phthalocyaninato) rare earth triple-deckers

Raman spectroscopic data in the range of 500-1800 cm(-1) for a series of nine mixed rare earth triple-deckers M-2[TO(OH)PP](Pc)(2) [M = La . . . Dy, except Pm; H(2)Por = 5-(4-hydroxyphenyl)-10,15,20-tris(4-octyloxyphenyl)porphyrin] have been collected using laser excitation sources emitting at 632.8 nm. Comparison with the Raman spectra of the corresponding bis(phthalocyaninato) and mixed double-decker rare earths reveals that the Raman characteristics of these mixed triple-deckers M-2(III)[TO(OH)PP](Pc)(2) are dominated by Pc2- contributions. There is no obvious band that can be assigned to the [TO(OH)PP](2-) moiety. Under excitation at 632.8 nm, typical Raman marker bands of the phthalocyanine dianions Pc2- were observed at 1514-1526 cm(-1) as medium band, resulting from the coupling of pyrrole C=C and aza C=N stretchings. For Ce-2(III-IV)[TO(OH)PP)(Pc)(2), a strong band at 1521 cm(-1) with contribution from both pyrrole C=C and aza C=N stretches as well as the isoindole stretches was the marker Raman band of Pc2-. The Raman spectra of these mixed triple-decker complexes reveal that most of the Raman vibrations derived from pyrrole stretching, isoindole breathing, C-H bend and aza stretching are decreased sensitive to the rare earth ionic size, and remain basically unchanged along with the lanthanide contraction. These facts indicate that the pi-pi interactions in these mixed triple-deckers are weaker than those in the double-deckers. (C) 2012 Elsevier B.V. All rights reserved.