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 M2[TO(OH)PP](Pc)2 [M = La…Dy, except Pm; H2Por = 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 M2III[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 CC and aza CN stretchings. For Ce2III-IV[TO(OH)PP](Pc)2, a strong band at 1521 cm−1 with contribution from both pyrrole CC and aza CN 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, CH 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 π–π interactions in these mixed triple-deckers are weaker than those in the double-deckers.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The Raman spectra of nine triple-deckers have been systematically investigated. ► Most of the Raman frequencies are decreased sensitive to the rare earth ionic size. ► The π–π interactions are weaker than those in the double-deckers.