1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

6 Experimental Section
(cyanomethyl)-substituted tetraarylporphyrin which is finally purified by FC over silica.
GP II: Saponification of o-(Cyanomethyl)-Substituted Porphyrin Systems to Porphyrin
Ethanoic Acids
In a 250 mL round bottom flask equipped with reflux condenser, the o-(cyanomethyl)
porphyrin system (up to 300 mg, obtained via GP I) is dissolved in a mixture of glacial AcOH,
conc. H2SO4 and water. Under vigorous stirring at 95 °C, the mixture is allowed to react for
80 h. After that, the dark green reaction mixture is poured on ice, whereupon the
protonated porphyrin carboxylic acid derivative precipitates completely. The residue is then
collected by filtration and washed once with water before it is taken up in CH2Cl2. That
solution is shaken out with water trice, washed with a dilute aqueous solution of NaHCO3
and with water. Drying over MgSO4 and removing the solvent furnishes the crude porphyrin
ethanoic acids being of adequate purity in most cases. Else, purification is to be achieved by
FC over silica.
GP III: Accessing Cycloketo-Porphyrin Systems Utilizing FRIEDEL-CRAFTS Chemistry
a. Preparation of Copper(II) Porphyrin Carboxylic Acid Complexes
In a 250 mL round bottom flask, the free base porphyrin carboxylic acid (e. g. obtained via
GP II) is dissolved in CH2Cl2 and acidified with some drops of glacial AcOH. Then a
concentrated methanolic solution of an excess (10 eq.) of Cu(OAc)2·H2O is added and the
reaction mixture is stirred at rt for 16 h. Afterwards, water is added and the layers are
separated. Subsequent washing of the organic layer with water twice, drying over MgSO4
and evaporation to dryness yields the desired copper(II) complexes as cherry-red powders to
be used without further purification.
b. FRIEDEL-CRAFTS Acylation to Close the Exocyclic Ring
In a 100 mL round bottom flask with N2 inlet, the metal complex (Cu(II) or Ni(II)) of an
appropriate porphyrin carboxylic acid (up to 200 mg, e.g. obtained from part a.) is dissolved
in abs. CH2Cl2 under inert gas atmosphere and under exclusion of water. Then an excess of
C2O2Cl2 is added and the flask is closed with a bubble counter as pressure relief valve. After
2 h of stirring at rt, the solvent and the reactant are completely removed under high vacuum
utilizing two coupled cooling traps. The residing dry acid chloride is directly redissolved in
abs. CH2Cl2 under N2 and exclusion of water again before SnCl4 is added. This mixture is then
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