New Porphyrinoid Triaza[22]annulenes from 1,9-Bis(5-formylpyrrol-2-yl)dipyrrins, Diaminomaleonitrile and o-Phenylenediamine - Drews, Axel; Schönemeier, Thomas; Seggewies, Stephan; Breitmaier, Eberhard (Synthesis, 1998)