A series of new styryl dyes containing N-phenyl-aza-15-Crown-5 moiety is synthesized and their complexation and spectroscopic properties are studied together with the parent macrocyclic compound and related benzothiazolic derivative. Stability constants of the corresponding Ca2+, Sr2+, Ba2+ complexes obtained in dry acetonitrile solution are determined spectrophotometrically. Two different mathematical approaches are developed enabling the spectrophotometric determination of stability constants in the cases when ligand and complex absorption bands are overlapping and the complex spectrum cannot be obtained experimentally.

An approach for quantitative spectrophotometric analysis of binary mixtures based on first derivative spectra is developed. The proposed method is used for investigation of the complex formation of some aza-15-crown-5-containing ligands with Sr(2+), where the stability constant is low and the absorption spectrum of the complex cannot be obtained directly. The described general approach can be applied for quantitative analysis of any other two-component mixture where the absorption spectra of the components cannot be obtained experimentally.

The spectral properties of a series of styryl dyes containing the aza-15-crown-5 macrocycle are investigated. Using absorption UV-Vis spectroscopy the protonation and aggregation processes are studied and the corresponding pKa values and dimerization constants Kd determined. Oligomer formation occurs in the presence of HClO4 and ClO42−, and a scheme describing these processes is suggested.

The complex formation of two styryl dyes, viz. 1-ethyl-2-[4-(1,4,7,10-tetraoxa- 13-aza-cyclopentadecyl)styryl]-benz[cd]indolium perchlorate 1 and 1,3,3-trimethyl-2-[4-(1,4,7,10-tetraoxa-13-aza-cyclopentadecyl)styryl] indolium perchlorate 2 with Ca(ClO4)(2) and Ba(ClO4)(2) was investigated spectrophotometrically in acetonitrile. The estimated log K-st values were found to be: I + Ca(ClO4)(2), 1.78 + 0.05; 1 + Ba(ClO4)(2), 1.25 + 0.02; 2 + Ca(ClO4)(2), 1.72 + 0.02; 2 + Ba(ClO4)(2), 1.25 + 0.03; pK(a) values for 1 and 2 were also determined.

The synthesis of 1-[(4-benzothiazolyl)phenyl]-4,7,10,13-tetraoxa-1-aza-cyclopentadecane, a new chromofluoroionophore is described. Its interaction with alkali and alkaline-earth metal salts in acetonitrile is investigated both spectrophotometrically and spectrofluorimetrically.

The complexation of 1-[(4-benzothiazolyl)phenyl]-4,7,10,13-tetraoxa-1-aza-cyclopenta-decane with Ba2+ and Ca2+ cations was investigated spectrophotometrically and spectrofluorometrically. The stability constants of the complexes formed are: for Ba2+ logKst=3.17±0.01 (absorption) and logKst=2.95±0.03 (fluorescence); for Ca2+ logKst=3.71±0.02 (absorption) and logKst=3.58±0.05 (fluorescence). Protonation of the ligand leads to fluorescence quenching. AM1 and PPP quantum chemical calculations were used to predict molecular geometry, proton affinities and the spectra of the compounds studied.

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Complexation of two cationic styryl dyes containing aza-15-crown-5 moiety and Na+, K+, Ca2+ and Ba2+ was investigated spectrophotometrically in water-containing acetonitrile medium. The ligand/complex ratio was estimated using a method for resolution of overlapping bands. A model for evaluation of the water action is proposed and stability constants were calculated for all metal ions in question.

Two extraction systems incorporating novel derivatives of benzothiazole are described for the determination of trace amounts of HgII and PdII by flame atomic absorption spectrometry (AAS). The extraction ability of the systems was studied both in strongly acidic (3 mol dm–3 HCl) and slightly acidic (Ph 5) media. By using the equilibrium shift method the composition of the extracted complexes was determined. The experimental data obtained indicate that the composition of the complexes depends on the acidity of the reaction system. A procedure for the extraction, separation, preconcentration and flame AAS determination of HgII in Pb, Cu and Cd salts was developed, allowing 2 × 10–4% Hg to be determined.

Seven new styryl dyes containing an aza-15-crown-5 moiety were synthesized and characterized by means of elemental analysis, m.p., UV, I R and 1H-NMR spectra. The colour change in the presence of metal salts was investigated.