Синтез и спектроскопическая характеристика комплексов рутения(II) с бипиридинами, содержащими модифицированный каликс[4]арен в качестве ионофора, электрохимия и исследования связывания ионов

In this book I have reported a number of molecular receptors containing ruthenium(II) bipyridine moiety as fluorophore andcalix[4]arene-azacrown hybrid molecule as an ionophore. All the molecules have been synthesized and characterized. These receptors (1–4) can produce significantly strong 3MLCT luminescence bands in the range 613–618 nm. The ion-binding property of these fluoroionophores have been investigated against a large number of cations like Na⁺, K⁺, Mg²⁺, Ca²⁺, Cs⁺, Zn²⁺, Cd²⁺, Hg²⁺, and Pb²⁺ ions. The ion recognition ability of the fluoroionophores (1–4) was monitored by luminescence, ¹H NMR spectroscopy, the oxidation potential of metal ions, and UV/Vis absorption studies. The luminescence study suggests complexation of all four receptors with Zn²⁺, Cd²⁺, and Hg²⁺ and for 2 and 3 also with Pb²⁺. The binding constants (Ks, except 4) and stoichiometries of the complexes have been calculated from the luminescence titration data, with values of Ks ranging from 2.53 x 10⁵ to 6.27 x 10³ M⁻¹. The 1H NMR spectroscopy study exhibits interactions of Na⁺ and K⁺ with 1 and 4, K⁺ and Cs⁺ with 2, and K⁺ with 3. Binding constants with these metal ions have been calculated from 1H NMR titrations using computer programs or by a direct method depending on the type of change in the chemical shifts observed upon addition of metal ions. Stoichiometry of the complexes has been determined from Job’s plot. Electrochemical properties of 1–4 have been studied in the absence and also in the presence of selected metal ions, and the shift of the oxidation potentials of the Ru(II) in the presence of guest ions suggests an interaction of Na⁺, Hg²⁺, and Pb²⁺ with 1 and 2 but not with 3 and 4, indicating a selective electrochemical response towards certain metal ions. The results obtained are presented and discussed in light of ion-binding properties and methods of detection.