Methoxy-substituted derivatives of 1,4-bis(2-phenylethenyl) benzene and of1,4-bis(2-phenylethyl) benzene as ligands in ion-selective electrodes for lead ions

We report the potentiometric responses towards lead ions of liquid membrane electrodes containing 1,4-bis[2-(3,4,5-trimethoxyphenyl)ethenyl]benzene (1 ),2,5-dimethoxy-1,4-bis[2-(3,4,5-trimethoxyphenyl)ethenyl]benzene (2),l,4-b is[2-(3,4,5-trimethoxyphenyl)ethyl]benzene (3) and 2,5-dimethoxy-1,4-bis[2- (3,4,5-trimethoxyphenyl)ethyl]benzene (4). All ligands strongly respond to lead ions in the activity range 10 (-6)-10 (-3) M and three show high selec tivity against common interfering mono- and doubly charged cations. ne new ligands demonstrate low affinity for protonation. Addition of 1 mol% of pot assium tetrakis(p-chlorophenyl)borate as a lipophilic anionic salt signific antly increases the selectivity of ligands 2, 3 and 4. The ligands show pot ential as sensory elements of liquid membrane electrodes destined for deter mination of lead ions. (C) 2001 Elsevier Science B.V. All rights reserved.