Triethylene Glycol Ether End-grafted Carbosilane Dendrimer: A Potential Ionophore for Potassium Ion Recognition

Abstract

The performance of a newly synthesized carbosilane dendrimer bearing four triethylene glycol ether (TEG) units, Si(CH₂CH₂CH₂Si(Me)₂CH₂CH₂CH₂(OCH₂CH₂)₃Me)₄ (1), as ionophores in ion-selective electrodes has been investigated. Optimization of the plasticized polyvinyl chloride membrane composition has produced electrodes that exhibit a Nernstian response for potassium ions. The best general characteristics exhibited by the electrodes were found when the membrane composition ratio of DPE:1:NaTPB:PVC 60:3:2:35 (wt%) was used. The response of the electrode was linear with a Nernstian slope of 58.3 mV/decade over the K⁺ ion concentration range of 1.9 × 10^-7 to 1.0 × 10^-1 M with a detection limit of 3.1 × 10^-7 M. The response time to achieve a 95% steady potential for the K⁺ concentration ranging from 1.0 × 10^-1 to 1.0 × 10^-8 M was less than 10 s, and it was found that the electrode is suitable for use within a pH range of 5.5 - 8.5. The selectivity coefficients (log K^Pot_K⁺,Mⁿ⁺), which were determined by the fixed interference method, showed good selectivity for K⁺ against most of the interfering cations. The influence of this selective ion-binding behavior using electrospray ionization time-of-flight (ESI-TOF) mass spectrometric studies is discussed.