Manganese(II)-selective PVC membrane electrode based on a pentaazamacrocyclic manganese complex

Manganese(II) complex of 14,16-dimethyl-1,4,7,10,13-pentaazacyclohexadeca-13,16-diene [Me₂(16)dieneN₅] (I) was synthesized and used in the fabrication of Mn²⁺-selective ISE membrane in PVC matrix. The membrane having Mn(II) macrocyclic complex as electroactive material along with sodium tetraphenylborate (NaTPB) as anion discriminator and dioctylphthalate (DOP) as plasticizer in poly(vinylchloride) (PVC) matrix was prepared for the determination of Mn²⁺. The best performance was observed by the membrane having Mn(II) complex–PVC–NaTPB–DOP in the ratio 1:5:1:3. The sensor worked well over a concentration range of 1.25 × 10⁻⁵ to 1.0 × 10⁻¹ M between pH 3.0 and 8.0 and had a fast response time of 20 s with a lifetime of 4 months. Their performance in partially non-aqueous medium was found satisfactory up to 30% (v/v) alcoholic content. Electrodes exhibited excellent selectivity for Mn²⁺ ion over other mono-, di-, trivalent cations. It can also be used as indicator electrode in the potentiometric titration of Mn²⁺ against EDTA.