Interaction of meso-tetraarylporphyrins with formic acid: A variable temperature 1H NMR study

Variable-temperature 1H NMR spectroscopy was performed in the range − 60 to 20 °C to study the diprotonated species of meso-tetraarylporphyrins (aryl = phenyl, 4-methoxylphenyl and 4-chlorophenyl) with formic acid as a weak carboxylic acid.