Ion Recognition


Ion recognition, thus chemical sensors based on Ion Selective Electrodes, or ISFET’s, Ion Selective Field Effect Transistors; transport membranes based on Supported Liquid Membranes (SLM’s) and Fixed Site Complexing Membranes (FSCM’s).

Ion Selective Electrodes: We have developed a new material based on polypyrrole (PPy) which uses the cobaltabisdicarbollide anion as a doping agent.   

Cyclic voltammetry of PPy[Co(C2B9H11)2] in aqueous alkaline chlorides 0.1 M: LiCl, NaCl, KCl, RbCl, CsCl.

The high volume of [Co(C2B9H11)2] imposes low mobility inside the polymeric matrix thus preventing dopant leakage when a reducing potential is applied on the material. Under these conditions the cation capture (Eq. 1) prevails during the reversible electrochemical redox process, also called doping/undoping. The membrane is highly sensitive to the cationic volume of the solute. This property has allowed us to develop cationic selective membranes of Li+, Na+, K+ and Rb+ by control of the applied reducing potential (Fig. 1). The chronocoulometries registered during the charge-discharge process show an almost perfect reversibility of cation exchange process and no detectable degradation of the membrane due to dopant loss or overoxidation even after 40 successive cycles.

[PPyn + (A)n] + nC+ + ne → [PPy(A)n(C+)n] (Equation1)

The electrode is suitable for pH measurements: Monoprotic titrations of strong alkalis with strong acids, and weak bases with strong acids.

This property has been applied to manufacture of hydrogen-selective microelectrodes on silicon needle-shaped substrates . The performance of the resulting solid-contact ion-selective microelectrodes (SCISME) was investigated by using potentiometric measurement and electrochemical impedance spectrometry. The feasibility of the fabrication technology is demonstrated and the devices operate satisfactorily, with a response showing good sensitivity and selectivity against common interfering cations in background solutions. The SCISME has been developed for organ monitoring during cardiac surgery or during transportation for transplants.


“Síntesis de Metalocarboranos Substituídos. Estudio de su actividad como transportadores en membranas líquidas”. (PB94/0226).

“Materiales poliméricos Polipirrol/Metalacarboranos para purificación de aguas y separación de gases” (MAT98-0921).


[1] C. Masalles, S. Borros, C. Viñas, F. Teixidor, Advanced Materials, 2000, 12, 1199 – 1202.
[2] C. Masalles, F. Teixidor, S. Borrós, C. Viñas, Journal of Organometallic Chemistry, 2002 , 657, 239 – 246.
[3] C. Masalles, S. Borrós, C. Viñas, F. Teixidor, Analitical and Bioanalytical Chemistry, 2002, 372, 513 – 518.
[4] N. Zine, J. Bausells, A. Ivorra, J. Aguiló, M. Zabala, F. Teixidor, C. Masalles, C. Viñas, A. Errachid, Sensors and Actuators B, 2003, 91, 76 – 82.

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