Abstract
Ionophore incorporated PVC membrane sensors are well-established analyticaltools routinely used for the selective and direct measurement of a wide variety of differentions in complex biological and environmental samples. Potentiometric sensors have someoutstanding advantages including simple design and operation, wide linear dynamic range,relatively fast response and rational selectivity. The vital component of such plasticizedPVC members is the ionophore involved, defining the selectivity of the electrodes' complexformation. Molecular recognition causes the formation of many different supramolecules.Different types of supramolecules, like calixarenes, cyclodextrins and podands, have beenused as a sensing material in the construction of ion selective sensors. Schiff's bases andcrown ethers, which feature prominently in supramolecular chemistry, can be used assensing materials in the construction of potentiometric ion selective electrodes. Up to now,more than 200 potentiometric membrane sensors for cations and anions based on Schiff's bases and crown ethers have been reported. In this review cation binding and anioncomplexes will be described. Liquid membrane sensors based on Schiff's bases and crownethers will then be discussed.
Highlights
From a color change in a flask to highly sophisticated biological mechanisms, every action that occurs around us is the result of chemical reactions and physicochemical interactions occurring in various combinations
Supramolecular chemistry, which is defined as the chemistry of molecular systems beyond individual molecules and which is highly dependant on the phenomenon of molecular recognition due to a host-guest relationship, was first established more than one hundred years ago
The mentioned metal–ligand interactions induce an anion-selectivity in the membrane that significantly differs from those observed in the case of conventional anion ionophores containing lipophilic quaternary ammonium or phosphonium salts, which lead to lipophilicity based selectivity patterns
Summary
From a color change in a flask to highly sophisticated biological mechanisms, every action that occurs around us is the result of chemical reactions and physicochemical interactions occurring in various combinations These reactions and interactions often seem to occur randomly, but this is rarely true. They often occur between selected partners–especially when the reactions and interactions occur in a highly organized system such as those found in biological settings–as the molecule recognizes the best (or better) partner This has helped elaborate the close relationship between this field and the complex supermolecular species, which are formed due to the effect of intermolecular forces on more than one chemical species, holding them together. Many new novel compounds with high selectivities for ion or molecule separation, transport and catalytic purposes have been developed by scientists who have been active in different branches of chemistry
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