1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

MS (FAB+, NBA): m/z = 535 (100) [M] +· .
Experimental Section 6
IR (ATR): 𝜈� [cm -1 ] = 3393, 2922, 1691, 1618, 1552, 1497, 1450, 1399, 1345, 1221, 1162, 1123,
1025, 979, 891, 785, 731, 674, 612.
UV/Vis (CH2Cl2): λ [nm] (ε [M -1 ·cm -1 ]) = 413 (85200), 508 (9700), 538 (9000), 610 (7700), 668
(37900).
6.2.3 General Procedures (GP’s)
GP I: Formation of o-(Cyanomethyl)-Substituted Porphyrin Systems from the
Corresponding o-(Bromomethyl) Porphyrin Precursors
a. Preparation of Zinc(II) Bromomethyl Porphyrin Complexes
The starting material is completely dissolved in CH2Cl2 in an appropriate round bottom flask
and a concentrated methanolic solution of an excess (20 eq.) of Zn(OAc)2·2H2O is added. The
reaction mixture is then stirred at rt until TLC control shows completion. The time usually
ranges in between 2 and 15 h depending on the level of substitution in the parental
bromomethyl porphyrin compound. Afterwards, the reaction mixture is transferred into a
separatory funnel, washed trice with water, dried over MgSO4 and evaporated to dryness to
give the corresponding zinc(II) complexes as pinkish powders.
b. Substitution of Bromide by Cyanide and Subsequent Demetallation
The dry zinc(II) complex (up to 250 mg) obtained from part a. is placed in a 100 mL
ERLENMEYER flask and mixed with a huge excess (50-100 eq.) of powdered KCN. After addition
of PEG 400, the suspension is stirred at rt for 24 h. Within that period, the suspension slowly
turns into a dark green-purple solution. Afterwards, the reaction mixture is transferred into
a separatory funnel, diluted with 100 mL of water and extracted with CH2Cl2 until the
aqueous layer becomes colorless. The combined organic extracts are then repeatedly
washed with water (at least trice) to get rid of residing cyanide before half-concentrated
aqueous HCl is added (100 mL) to the purple solution turning green immediately. After
vigorous shaking for several minutes, the organic layer is separated and washed with 2 M
aqueous HCl and with water until the organic layer appears purple. Subsequent
neutralization by shaking out with a saturated aqueous solution of NaHCO3, washing with
water, drying over MgSO4 and evaporation to dryness yields the corresponding free base o-
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