Chromogenic Indicator for Anion Reporting Based on an N-Substituted Oxoporphyrinogen

5,10,15,20-Tetrakis-3,5-di-tert-butyl-4-oxocyclohexadienylidene porphyrinogen and its di-N-benzylated derivative are
solvatochromic dyes capable of binding anionic species. The influence of solvent polarity and hydrogen bonding on
their electronic absorption spectra was observed. Hydrogen bonding by the porphyrinogen amine protons of acetone
solvent molecules could be observed in the solid state. The acetone solvate of N21N23-dibenzyl-5,10,15,20-tetrakis-3,5-di-tert-butyl-4-oxocyclohexadienylidene porphyrinogen crystallized under anhydrous conditions in the space group
P1̄ with cell dimensions a = 12.1693(11) Å, b = 17.5849(13) Å, c = 21.0965(17) Å, α = 69.870(4)°, β =
78.140(4)°, γ = 82.865(5)°. These porphyrinogens are capable of binding a variety of anions and can be used to
distinguish fluoride chromogenically from the other halide anions. Solvatochromism was combined with anion binding
in an attempt to provide more selective tests for anions. The anion binding properties were investigated using
UV/vis spectrophotometry and 1H NMR spectroscopy.