Aminoferrocene Derivatives in Chloride Recognition and Electrochemical Sensing

New ferrocenylamine derivatives 1,3-C6H4(CONHFc)2 (3), 1,3-C6H4(SO2NHFc)2 (4), and 1,3-C6H4(CONHFc)(COOEt) (5) (Fc = ferrocenyl), readily synthesized from FcNH2 and the appropriate acid dichlorides, bind chloride 1:1 as shown by 1H NMR, FT-IR, and cyclic voltammetry. NMR titrations gave association constants as high as 9.5 × 103 (for 4·Cl-). Cyclic voltammetry of 4·Cl- vs 4 shows a 20 mV negative shift for the ferrocene wave, indicating Cl- binding. An improved synthesis of FcNH2 is reported.