Binding ability of Zn-tetraarylporphyrins with two, four and eight 4-(4-(3,6-bis(t-butyl)carbazol-9-ylphenyl)-1,2,3-triazole end groups towards N-containing substrates of different nature

The binding ability of Zn-tetraarylporphyrins with two, four and eight 4-carbazolylphenyl-1,2,3-triazole end groups towards 1,4-diazabicyclo[2.2.2]octane, pyridine and 1,2,3-triazole in toluene was studied by spectrophotometric and 1H NMR titration. It was determined that due to a good geometric match of the ligand size to the size of the intramolecular cavities of the porphyrinic receptor, and by the existence of additional and/or hydrogen bonding interactions between the ligand and the triazole fragments of the porphyrin, the Zn-tetraarylporphyrin with eight 4-carbazolylphenyl-1,2,3-triazole end groups could be used as an effective receptor for 1,2,3-triazole and other small heterocycles such as pyridine. Taking into account the fact that binding is accompanied by a clear and easily identifiable response in the UVvis spectra of the reaction mixture, this metalloporphyrin could be considered as a molecular optical sensing device for small heterocyclic substrates.