Sealants for inhibiting corrosion

A method of protecting a substrate from corrosion comprising applying a coating composition to a surface of the substrate, wherein the coating composition comprises:

• a corrosion inhibitor comprising a metal organic framework (MOF) comprising a metal ion each coordinated to one or more organic ligands,
• wherein the one or more organic ligands comprise at least one exocyclic sulphur group represented by Formula 1:
• wherein, A is a 5- or 6-membered aryl, heteroaryl or heterocyclic ring, which is optionally substituted with one or more substituents and optionally fused with one or more aryl or heteroaryl rings, wherein a dotted line represents one or more optional double bonds;
• Y1 is selected from S or SH, wherein a dotted line represents a double bond when Y1 is S or is absent when Y1 is SH;
• X1 is selected from N, NH, O, and S;
• X2 is selected from N, NR5, O, S, CR6 and CR7R8;
• R5 is selected from hydrogen, amino, C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C2-C10 aryl, and C2-C10 heteroaryl, in which each amino, alkyl, alkenyl, alkynyl, aryl or heteroaryl group can be optionally substituted;
• and
• R6, R7 and R8, are each independently selected from hydrogen, halo, thiol, amino, C1-C10 alkyl, C2-C10 alkenyl, C2-C10 alkynyl, C2-C10 aryl, and C2-C10 heteroaryl, in which each amino, alkyl, alkenyl, alkynyl, aryl or heteroaryl group can be optionally substituted, and
• wherein the metal ion of the MOF comprises a rare earth metal or transition metal;
• and
• a sealant comprising a non-stoichiometric sensitive composition and an activator.