Synthesis and characterization of lead metallated non-peripherally substituted octa-octyl tetrabenzo(aza)porphyrins showing face-to-face columnar stacking in the crystal phase

Abstract

The full range of porphyrin-phthalocyanine hybrids can be synthesized by treatment of 1,4-dioctylphthalonitrile with varying equivalents of MeMgBr to produce mixtures favoring specific hybrid structures and the tetrabenzoporphyrin in the extreme case. The individual macrocycles can be isolated in pure form as their magnesium derivatives and subsequently demetallated to give the parent metal-free compounds. Insertion of lead proceeded smoothly with all hybrids using lead (II) acetate. In the case of monoaza- and triaza-hybrids, the resulting materials could be recrystallized to give crystals suitable for X-ray diffraction. The crystal structures are distinctive from previously reported examples of non-peripherally substituted octaalkyl phthalocyanines and hybrids (metal-free and metallated, including with lead) and they each present infinite stacks of cofacial macrocycles linked through bridging lead ions which, as expected, lie outside of the macrocycle plane.