Polymeric phthalocyanines and their precursors, 7. Synthesis and analytical characterization of polymers from 1,2,4,5‐benzenetetracarboxylic acid derivatives

Structurally uniform polymeric phthalocyanines 5a–e, containing imido end groups, were synthesized by reaction of different derivatives of 1,2,4,5‐benzenetetracarboxylic acid, 2a–d, with metal salts, urea and a catalyst. 5a–e were converted into polymers 3, 4 and 6, containing anhydride, carboxylic acid and amido end groups, respectively. IR and UV/VIS spectroscopy were used as appropriate methods for describing end groups and structural uniformity. It could be shown that the octasubstituted phthalocyanines 7–10 and not the phthalocyanine 1 must be considered as the low‐molecular‐weight analogues. The number of phthalocyanine units in the polymers was found to be ⩾ 9. The determination of the real molecular weights is not possible, due to the low solubility of the polymers.