Synthesis, electrochemistry and liquid crystal properties of 1,2,3-(NH)-triazolylferrocene derivatives

A series of aryl(5-ferrocenyl-2H-1,2,3-triazol-4-yl)methanone 3a–3d have been firstly synthesized and characterized. The X-ray crystal structure of phenyl(5-ferrocenyl-2H-1,2,3-triazol-4-yl)methanone 3a confirms that 1,2,3-triazole ring exists in the crystal as the 2H isomer form. The UV–vis absorption spectra of these compounds correspond to the assembled spectra of ferrocene and aryl substitute groups, and the fluorescence spectra show a maximum at 374 nm in CH2Cl2. The cyclic voltammograms of 3b–3d show the reversible oxidation waves of the ferrocenyl groups, and these waves anodically shift in comparison with ferrocene standard due to the electron withdrawing effect of the 1,2,3-triazoles ring. According to thermal polarizing microscopy and differential scanning calorimetry studies, compounds 3b–3d display liquid crystal behaviors over wider mesophase range during first heating.