Novel Silver(I) Ion Selective PVC Membrane Electrode Based on the Schiff Base (N2E,N2′E)-N2,N2′-Bis(Thiophen-2-ylmethylene)-1,1′-Binaphthyl-2,2′-Diamine

A potentiometric sensor based on the Schiff base ((NE)-E-2,(NE)-E-2')-N-2,N-2'-bis(thiophen-2-ylmethylene)-1,1(')-binaphthyl-2,2(')-diamine has been synthesized and explored as an ionophore PVC-based membrane sensor selective for the silver (Ag+) ion. Potentiometric investigations indicate a high affinity of this receptor for the silver ion. Seven membranes have been fabricated with different compositions, with the best performance shown by the membrane with an ionophore composition (w/w) of: 1.0 mg, PVC: 33.0 mg, DOA: 66.0 mg in 1.0 mL THF. The sensor worked well within a wide concentration range of 1.0 x 10(-2) to 1.0 x 10(-7) M, at pH 5, at room temperature (slope 57.4 mV/dec.), and with a rapid response time of 9 s; the sensor also showed good selectivity towards the silver ion over a huge number of interfering cations, with the highest selectivity coefficient for Hg2+ at -3.7. Thus far, the best lower detection limit was 4.0 x 10(-8)M.