Separation of 2(3),9(10),16(17),23(24)-Tetrasubstituted Phthalocyanines with Newly Developed HPLC Phases

Abstract

The synthesis of 2(3),9(10), 16(17),23(24)-tetrasubstituted phthalocyanines from 1,2-dicyano-4-alkoxybenzenes or the corresponding isoindolines is reported. In each case, four isomers with D 2h , C 4h , C 2V , and C s symmetry are obtained in the statistical expected yield. The separation of the C 4h and the D 2h isomers was achieved successfully for the first time from the other two isomers with newly developed HPLC phases based on π-π interactions. In one case, phthalocyanine 12 could be separated into the isomers 12a-d and characterized by UV/vis and 1 H-NMR spectroscopy. Due to line broadening at room temperature, T 1 and T 2 relaxation time measurements of two phthalocyanines (3 and 12) at different temperatures are carried out. Whether the broad peaks are due to aggregation or due to a short relaxation time is explained.

Synthesis and Isolation of 2,9,17,23-Tetrakis[(3,5-dimethyl-1H-pyrazol-1-yl)phenoxy]phthalocyanine and Its Magnesium(II) and Zinc(II) Complexes

“…This phenomenon is caused by the fact that due to the small chemical shift difference of protons of four isoindole fragments of C S regioisomer, a signal overlap occurs in the spectra. [41,45] Each of the two methyl groups on the pyrazole ring gives rise to four signals in the high field region, which resembled a pair of doublets, whereas in the spectrum of phthalonitrile 1 methyl protons resonate, as might be expected as two singlets. The signals of protons in the pyrazole rings also appear by four signals like a pair of doublets, whereas in the spectrum of phthalonitrile 1 the signal of proton appears as a singlet.…”

“…Some bands in IR spectra of phthalocyanines 2-4 are broad because, as known, [41] vibration bands overlap for C S regioisomers of phthalocyanines. The C≡N vibration bands (2230 cm -1 , sharp, for phthalonitrile 1) are absent that confirm the cyclotetramerization of the phthalonitrile into the phthalocyanines (Figure 2).…”

“…[41][42][43] In order to prevent aggregation, the 1 H NMR spectra of phthalocyanines 2-4 were recorded in dilute solutions (0.5 mg per 1 mL). The 1 H NMR spectra of magnesium phthalocyanines 3 and zinc phthalocyanine 4 practically do not differ from each other.…”

“…The separation of the mixture of the four regioisomers by column chromatography is highly challenging [40] and was achieved by preparative thin layer chromatography or HPLC with chiral column. [41][42][43][44][45][46] It is known that due to the presence of bulky substitutients, a pure regioisomer of 3-substituted ZnPc can be isolated by column chromatograpy. So, the one C 4h isomer of non-peripheral 3-(alkylaryloxy)-tetrasubstituted phthalocyanine was isolated by column chromatography in high yield.…”

Synthesis and Properties of Tetrakis(trimethylsilyl)-phthalocyaninatoruthenium(II)

“…In general, tetra-and trisubstituted phthalocyanines are formed as mixtures of four [13][14][15] and the disubstituted complex as a mixture of five structural isomers. The disubstituted complex 4, which could only be isolated in a very small amount, was simply characterized as a mixture of isomers by its 1 H NMR spectrum (in Scheme 1, formula 4 shows only one of the five possible isomers which were not separated).…”