The Long-Lasting Story of One Sensor Development: From Novel Ionophore Design toward the Sensor Selectivity Modeling and Lifetime Improvement

Larisa Lvova,Corrado Di Natale,Roberto Paolesse,Donato Monti

doi:10.3390/s21041401

Larisa Lvova, Corrado Di Natale + Show 2 more

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https://doi.org/10.3390/s21041401

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Abstract

The metalloporphyrin ligand bearing incorporated anion-exchanger fragment, 5-[4-(3-trimethylammonium)propyloxyphenyl]-10,15,20-triphenylporphyrinate of Co(II) chloride, CoTPP-N, has been tested as anion-selective ionophore in PVC-based solvent polymeric membrane sensors. A plausible sensor working mechanism includes the axial coordination of the target anion on ionophore metal center followed by the formed complex aggregation with the second ionophore molecule through positively charged anion-exchanger fragment. The UV-visible spectroscopic studies in solution have revealed that the analyte concentration increase induces the J-type porphyrin aggregation. Polymeric membranes doped with CoTPP-N showed close to the theoretical Nernstian response toward nitrite ion, preferably coordinated by the ionophore, and were dependent on the presence of additional membrane-active components (lipophilic ionic sites and ionophore) in the membrane phase. The resulting selectivity was a subject of specific interaction and/or steric factors. Moreover, it was demonstrated theoretically and confirmed experimentally that the selection of a proper ratio of ionophore and anionic additive can optimize the sensor selectivity and lifetime.

Highlights

The success of new chemical sensors’ development in very high degree depends on the tailored choice of an appropriate ligand/ionophore responsible for selective analyte binding, and determining the sensor stability, reproducibility, and lifetime
We reported the progress in our studies on ICPP-9 (International Conference on Porphyrins and Phthalocyanines) [27], describing the influence of ionophore aggregation on sensor reexperimental data
An application of self-aggregating macrocycle bearing incorporated anionexchanger fragment, 5-[4-(3-trimethylammonium)propyloxy-phenyl]-10,15,20-triphenylpor phyrinate of Co(II) chloride, CoTPP-N, as a sensitive ligand in solvent polymeric membrane electrodes was investigated for a first time

Summary

Introduction

The success of new chemical sensors’ development in very high degree depends on the tailored choice of an appropriate ligand/ionophore responsible for selective analyte binding, and determining the sensor stability, reproducibility, and lifetime. Among anion-selective ionophores metalloporphyrins are most widely used due to their rich electrochemical and optical properties and high structural versatility, which can be modulated both through the incorporation of various main-core substituents and/or through different central metal selections [1,2]. Metalloporphyrin-based chemical sensors, and potentiometric ion selective electrodes (ISEs), in particular, are popular devices for specific detection of anions since they demonstrate the selectivity, different from the lyotropic Hofmeister series, determined by energies of hydration of target analyte [3]. The covalent attachment of the porphyrin ionophore to the various supports and further incorporation into polymeric matrices, for instance, polymethacrylate [19,20] or Single-Walled Carbon Nanotubes (SWCNTs) [21], the exploitation of highly lipophilic metalloporphyrin ionophores bearing bulky side moieties, as for instance, Ge(IV)-tert-butyl-tetraphenylporphyrin, Ge(IV)-tBTPP, reported in [22], or use of

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