The potentiometric behavior of polymer supported metalloporphyrins as anion-selective electrodes

The potentiometric behavior of polystyrene pyridine copolymer supported man ganese (III) and tin (IV) protoporphyrin IX (MnPPIX-PSP4 and SnPPIX-PSP4) w as investigated. As expected, both MnPPIX-PSP4 and SnPPIX-PSP4-based membra ne electrodes showed size exclusion effects on salicylate, these may be cau sed by a cross-linked polymer matrix which can act as an asymmetric cellulo se membrane to exclude the bigger sized lipophilic anions such as salicylat e. Pyridine attached to the polymer chain can influence the selectivity pat tern of the aforementioned membrane electrodes as the axial ligand to the c entral metal of the porphyrins. The Lifetimes of the polymer supported iono phore-based membrane electrodes are significantly enhanced from those of po rphyrin-based electrodes and the super-Nernstian phenomenon found on Sn por phyrin-based membrane electrodes also disappeared. (C) 2001 Elsevier Scienc e B.V. All rights reserved.