Novel azaphthalocyanines with efficient anti-corrosion capability: Effect of halogens and heavy metals

Abstract

A series of azaphthalocyanines (AzaPcs) substituted with peripheral 2,6-dihalogenated (Cl, Br or I) phenoxyl groups containing different central ions [2H+, Zn (II), Mg (II) or In (III)] were synthesized and their structural characterization were confirmed. Non-aggregation behavior exhibited by all the prepared complexes was perfectly achieved as confirmed by single crystal analyses due to the bulkiness of their peripheral substituents. Based on physicochemical analyses including fluorescence and singlet oxygen quantum yields, heavy metal effects were determined, and consequently, the highest singlet oxygen was recorded by the indium complex bearing iodine atoms (AzaPc12). The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) results revealed that the investigated azaphthalocyanine molecules pronouncedly retarded the mild steel corrosion in the acidic media by adsorbing at the metal/electrolyte interface. Theoretical DFT and molecular dynamic simulation studies supported the experimental results with the best inhibition efficiency achieved with AzaPc12. Surface morphology of mild-steel was examined by AFM and SEM techniques. The results proved the strong adsorption of AzaPc12 on the steel surface, forming a protective film which consistent with the electrochemical and theoretical results. The findings of this research obviously show a simple approach to the manufacture of phthalocyanine-derivatives that can find significant industrial application in metal corrosion suppression.