Acid-base and spectroscopic properties of a novel supramolecular porphrin bonded to four pentacyanoferrate(II) groups - Winnischofer, Herbert; Engelmann, Fábio Monaro; Toma, Henrique Eisi; Araki, Koiti; Rechenberg, Hercilio Rodolfo (Inorganica Chimica Acta, 2002)