Bis-benzimidazole diamide iron(III) complexes as mimics of phenoxazinone synthase

New Bis Benzimidazole diamide ligands-N,N′-Bis(2-Methylbenzimidazolyl) pyridinediamide [GBPA = L1] and N-Picolylated-N,N′-Bis(2-Methylbenzimidazolyl) hexandiamide [Pic-GBHA = L2] have been synthesized and utilized to prepare Fe(III) complexes. The X-ray structure of the ligand L2 crystallizes in the monoclinic space group P21/n. The complexes were suitable as catalyst for the oxidation of 2-aminophenol (OAPH) to 2-aminophenoxazine-3-one (APX) (phenoxazinone synthase activity) with dioxygen at ambient temperature. Kinetic measurements revealed dependence on the substrate concentration with respect to the corresponding catalyst. The results show that the oxidation of OAP is not dependent upon E1/2 values of the respective complexes.

► N-Picolyl Benzimidazole diamide are used to prepare iron complexes.
► Iron complexes are used for the oxidation of o-aminophenol.
► Oxidation is independent of E1/2 values of complexes.
► Reaction follows 1st order kinetics with respect to substrate.