A new arylimido derivative of polyoxometalate (Bu4N)2[Mo6O17(NAr)2] [Ar = 2,6-(CH3)2C6H3]: Synthesis, structure and physicochemical properties

A novel bifunctionalized arylimido derivative of hexamolybdate, (Bu₄N)₂Mo₆O₁₇(NAr)₂] Ar = 2,6-(CH₃)₂C₆H₃] (1), in which the two 2,6-dimethylaniline groups are bounded to hexamolybdate at the cis positions, was synthesized by a facile reaction of α-octamolybdate with 2,6-dimethylaniline using DCC as a dehydration agent. The existence of strong non-typical C-H?O hydrogen bonds plays an important role in crystal structure stabilization of compound 1. The results of fluorescence spectra show that the formation of a covalent bond between 2,6-dimethylaniline molecule and hexamolybdate could efficiently quench the fluorescence intensity of 2,6-dimethylaniline molecule, with a fluorescence quencher efficiency of 87.7%. Thermal analysis results indicate that two substituted 2,6-(CH₃)₂C₆H₃ molecules bonding to the same cluster dissociated at different temperature, in well agreement with the different MoN bond length in compound 1. The electrochemical behavior of modified 1-CPE has been studied in detail. Compared with the conventional polyoxometalate (POM)-modified electrode, 1-CPE presents a merit of remarkable stability over 500 cycles due to the insolubility of the POM nanoparticles, which is especially important for practical applications.