Compact Metal-Organic Frameworks for Anti-Corrosion Applications: New Binary Linear Saturated Carboxylates of Zinc

Zinc-based metal-organic frameworks (MOFs), binary zinc carboxylates ZnCnCn` with C-n and C-n` = CH3(CH2)(n-2)COO-, have been synthesised and characterised for anti-corrosion applications. The crystallographic structures of ZnC10C14 and ZnC10C16 were determied from synchrotron powder diffraction data and refined by the Rietveld method. Protective coatings on electrogalvanised steel composed of ZnC12C16 have been developed by formulating a particular carboxylating bath. The ZnC12C16 coating exhibits better anti-corrosion behaviour than the pure Zn(C-16)(2) and Zn(C-12)(2) coatings, according to electrochemical and non-electrochemical measurements. The crystallographic results and corrosion measurements demonstrate the great flexibility of the zinc carboxylate lamellar structures in modifying the insolubility and hydrophobicity of the protective coatings. In addition, the conditions for the ZnC12C16 coating process fulfil the specifications for the surface treatment of zinc. Finally, these new compounds, which can be easily synthesised in water, provide a new and environmentally friendly anti-corrosion treatment for metals.