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The polyazacycloalkanes, 1,4,8,11-tetra(n-octyl)-1,4,8,11-tetraazacyclotetradecane (L1), 1,4,7,10,13-penta(n-octyl)-1,4,7,10,13-pentaazacyclopentadecane (L2) and 1,4,7,10,13,16-hexa(n-octyl)-1,4,7,10,13,16-hexaazacyclooctadecane (L3) have been synthesised, characterised and the ability of these polyamines as anion receptors has been studied using them as ionophores in PVC membrane anion-selective electrodes. The PVC membranes containing L1, L2 and L3 gave a linear response in the presence of perchlorate. The EMF response characteristics of these membrane-based perchlorate-selective electrodes and the selectivity coefficients using DOS, DBP or NPOE as plasticisers have been determined. The perchlorate-selective electrodes gave anion-selectivity patterns that basically follow the Hofmeister Series, expect the ISE containing L1 and DOS as plasticiser.

The new open-chain polyazaalkanes ligands L 1 , L 2 , L 3 and L 4 functionalised with one or two pyrene groups were synthesised and characterised and their potential use as selective cation and anion sensing chemosensors studied. Solution studies by potentiometric methods were carried out in the presence of the metal cations Cu 2+ and Zn 2+ in acetonitrile–water (70:30 v/v, 0.1 mol dm −3 tetrabutylammonium perchlorate, 25 °C) The results are compared with those reported for the analogous non-functionalised ligand triethylentetraamine ( tta ). The fluorescence behaviour of the ligands L 1 –L 4 has been studied as a function of the pH in the presence of the metal cations Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ and Pb 2+ in acetonitrile–water 70:30 v/v mixtures. The Zn 2+ and Cd 2+ cations enhance the fluorescence emission of the L 1 –L 4 chemosensors at basic pH, whereas Cu 2+ induce quenching of the fluorescence emission at acid pH. The fluorescence behaviour of L 1 –L 4 receptors was also studied as a function of the pH in acetonitrile–water 70:30 v/v in the presence of anions.

The ligand 1,4,8-tri(n-octyl)-1,4,8,11-tetraazacyclotetradecane (L1) containing pendant octyl groups has been synthesised. L1 is a tetraazamacrocycle derived from the well-known cyclam unit, and the Ni2+ and Co2+ complexes, [Ni(L1)]2+ and [Co(L1)]2+, have been isolated and characterised. The ability of the nickel(II) and cobalt(II) complexes to act as anion receptors has been studied by using them as ionophores in membrane-based ion-selective electrodes (ISEs). The PVC membrane containing the complex [Ni(L1)]2+ and 2-nitrophenyloctylether as plasticizer shows a Nernstian response against iodide in a concentration range from 1×10−1 to 4×10−5 M I− with a detection limit of 1.6×10−5 M I− and a slope of 58.6 mV/pI− at pH 7 (25 °C). In comparison, the electrode containing [Co(L1)]2+ as ionophore gave a sub-Nernstian slope and a low lifetime. A comparison between the iodide-selective electrode containing [Ni(L1)]2+ and other reported iodide-selective electrodes is also reported.

The ionophore 1,4,7,10,13-penta(n-octyl)-1,4,7,10,13-pentaazacyclopentadecane (L1) was used for the development of miniaturised perchlorate-selective electrodes in thick-film technology. Different PVC membranes containing L1 and the plasticizers o-nitrophenyl octyl ether (NPOE), dibutyl phthalate (DBP), bis(2-ethylhexyl)sebacate (DOS) and dibutyl sebacate (DBS) were prepared and placed on a graphite working electrode manufactured by using thick film serigraphic technology. The perchlorate selective electrode containing DBS as plasticizer showed a potentiometric Nernstian response of -57 mV per decade in a range of perchlorate concentration from 1 × 10-4 to 1 × 10-1 M with a detection limit of 5 × 10-5 M. The ion selective electrodes containing DBP and NPOE as plasticizers exhibit a working range from 6.3 × 10-5 to 1 × 10-1 M and 7.4 × 10-5 to 1 × 10-1 M for perchlorate, respectively, with a detection limit of ca. 2.2 × 10-5 M. For all three electrodes a response time of ca. 5 s was found. The prepared electrodes do not show appreciable decay of the slope for at least 25 days. Potentiometric selectivity coefficients (log KpotClO4-,X-) with respect to the primary anion perchlorate were evaluated using the fixed interference method. These coefficients are of the order of 10-1.7 or smaller, indicating the relatively poor interference of the different anions studied.

The new cyclic polyazacycloalkane 1,4,8,11-tetra(n-octyl)-1,4,8,11-tetraazacyclotetradecane (L1) was synthesised and the copper(II) complex [Cu(L1)]2+ characterised. Different electrodes were prepared using the [Cu(L1)]2+ complex as ionophore, PVC as plastic matrix and o-nitrophenyl octyl ether (NPOE), bis(2-ethylhexyl) sebacate (BEHS) or dibutyl phthalate (DBP) as plasticizers. The electrode containing DBP showed a Nernstian response over a wide pH range and a fast response time (ca. 3 s) whereas NPOE and BEHS gave near-Nernstian slopes. Selectivity coefficients for the different anions with respect to perchlorate were calculated. The response of the electrodes basically followed the Hofmeister sequence, suggesting that interaction of the ionophore with the anions is via electrostatic forces rather than due to anion coordination to the axial sites of the square-planar [Cu(L1)]2+ complex.

A remarkable enhanced response towards the hydrophilic anion sulfate using plasticized PVC membranes containing the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate and a polyazacycloalkane derivative as ionophore has been found.