Electrochemical Measurements. The electrochemical measurements were carried out by using CH Instruments 617D potentiostat-galvanostat system. The electrochemical cell containing a Ag wire as a reference electrode (RE), a Pt wire as counter electrode (CE) and glassy carbon as a working electrode (WE) immersed in 0.1 M tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte under argon atmosphere. In addition, oxidation potential onsets determined from the cyclic voltammetry (CV) were used for the HOMO level calculations by using the equation EHOMO = -e (Eox -EFc) + (-4.8 eV) according to the ferrocene oxidation E(Fc/Fc + ) = 0.41 V as internal standard.