Zinc(ii) triazole meso-arylsubstituted porphyrins for UV-visible chloride and bromide detection. Adsorption and catalytic degradation of malachite green dye

Abstract

Three new triazole meso-arylporphyrins (4a–c) were synthesized by the copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) “click” reaction in high yield. The corresponding zinc(II) coordination compounds (5a–c) have also been prepared. All 4a–c and 5a–c porphyrin species were fully characterized by elemental analysis, electrospray ionization and MALDI-TOF mass spectrometry, infrared spectroscopy, proton nuclear magnetic resonance, UV-visible, fluorescence and cyclic voltammetry. The zinc(II) 5a–c complexes have been tested as detectors for Cl⁻ and Br⁻ anions. UV-visible titrations reveal that these host systems exhibit strong anion binding affinities. The efficiency of the adsorption of the malachite green dye (MG) dye on the 4a–c free base porphyrins and the corresponding zinc(II) complexes 5a–c was investigated by a kinetic study using these synthetic porphyrin derivatives as adsorbents. The use of our triazole Zn(II) complexes in the catalytic degradation of the MG dye is the first example where a metalloporphyrin is involved in the MG dye decolorization reaction. The degradation reactions were carried out using an ecological oxidant (H₂O₂), where the efficiency of the decolorization has been characterized by UV-visible spectroscopic analysis. Several factors affecting the degradation phenomenon have been studied. The energetic parameters concerning the degradation process have also been determined.