Chromatographic Separation of the Four Possible Structural Isomers of a Tetrasubstituted Phthalocyanine: Tetrakis(2‐ethylhexyloxy)phthalocyaninatonickel(II)

Abstract

As a result of their different symmetry, the four structural isomers of the title compound (the C4h isomer 1 is depicted on the right) could be characterized by 1H NMR spectroscopy. With these complexes the complete chromatographic separation of the four structural isomers of tetrasubstituted metal phthalocyanines was achieved for the first time. R  2‐EtC6H12O.

The syntheses of 2,9,16,23- and 1,8,15,22-tetrahydroxyphthalocyanines

“…Spectroscopic and physical properties NMR spectroscopy of 2,9,16,23-tetrasubstituted phthalocyanines generally exhibits broad absorptions in the aromatic and other spectral regions due to the presence of four isomers, but occasionally the resonances can be resolved (15,30 (19). In contrast, in our research, the 1,8,15,22-tetra@-n-butylbenzyloxy)phthalocyanine (21) and its zinc derivative (22) were produced excl~~sively, presumably due to the greater steric constraints of the p-n-butylbenzyloxy substituent.…”

“…Although the 2,9,16,23-tetraneopentoxyphthalocyaninato zinc(I1) (16) and 2,9,17,24-tetra-tert-butylphthalocyaninato zinc(I1) (17) were produced as pure isomers; several reaction steps were used and only low yields were obtained. The synthesis of a single isomer of I,2-naphthalocyanine has been achieved (18) due to the steric constraints of the benzo substituents, but other 1,8,15,22-tetrasubstituted phthalocyanines gave mixtures of isomers that in one example could be separated by high performance liquid chromatography (HPLC) (19). In this paper we report the exclusive synthesis of two 1,8,15,22-tetrasubstituted phthalocyanines and their zinc derivatives as pure single isomers in high yields under common conditions.…”

Synthesis, Separation and Characterization of Naphthobenzo-condensed Porphyrazinato Nickel(II) Complexes

“…Since different numbers of tetrabenzo-substituted isoindole units lead to different masses, the products 13a, 13b, 13e, 14b, 14e, 15b and 15e respectively can be unequivocally identified by mass spectrometry. 1 H NMR spectroscopy is a very useful tool to determine the structure of unsymmetrically substituted phthalocyanines [1,11]. The 1 H NMR spectra of phthalocyanines [3,20] and 2,3-naphthalocyanines [21] are known to show large diamagnetic ringcurrent shifts and signals of the aromatic protons appear at low field.…”

“…For the preparation of unsymmetrical phthalocyanines several strategies can be applied: the polymer support route [9], via subphthalocyanines [10], or a statistical condensation [2] including the separation of the statistical mixture of the different constitutional isomers or products which are normally formed in the synthesis of Pcs starting from either unsymmetrically substituted phthalodinitriles [11] or phthalodinitriles of different structure [1,12]. Using the first two methods, only one product, formed by three identical and one other isoindole unit, should Scheme 1.…”

The use of bisphthalonitriles in the synthesis of side-strapped 1,11,15,25-tetrasubstituted phthalocyanines

“…5) result in an enhanced bathochromic shift of the Q-band in their UV-VIS spectra (1,7,28,29), when compared to similar substitution at the 2 , 3 , 9 , 10, 16, 17,23, and 24 positions of the PC nucleus. Thus, 5 shows a typical A, , , at 726 nm.…”