Охарактеризовано фізико-хімічні властивості 3-(2-піридил)-5-(2-гідроксіфеніл)-1,2,4-тріазолу (logP=3,0±0,1, рКа1= 3,98±0,05, рКa2=8,74±0,03, [формула] 1,36·104 л·моль-1·см-1). Інтенсивна флуоресценція ліганду спостерігається у довгохвильовій ділянці спектра [формула] 535 нм. Можливість використання даного ліганду як реагенту-флюорофору доведено при флуориметричному визначенні вмісту цинку у зразку волосся та таблетці вітамінів "Дуовіт". Розроблені методики дають задовільно правильні та відтворювані результати.
Охарактеризованы физико-химические свойства 3-(2-пиридил)-5-(2-гидроксифенил)-1,2,4-триазола (logP=3,0±0,1, рКа1=3,98±0,05, рКa2= 8,74±0,03, [формула]1,36·104 л·моль-1·см-1). Интенсивная флуоресценция лиганда наблюдается в длинноволновой области спектра [формула] 535 нм. Возможность применения такого лиганда как реагента-флуорофора подтверждена при флуориметрическом определении содержания цинка в образце волос и таблетке витаминов "Дуовит". Разработанные методики обеспечивают достижение удовлетворительно правильных и воспроизводимых результатов.
The development of new fluorescent reagents for determination of trace amounts of zinc in biological samples is an actual issue. Efficient reagents should characterized by high hydrophobicity, low& sensitivity to media acidity and intense fluorescence in the long-wavelength region of the spectrum. Therefore, the using of a rigid ?-conjugated molecule of 3-(2-pyridyl)-5-(2-hydroxyphenyl)-1,2,4-triazole as a fluorescent probe for the determinati&on of zinc micro-quantities in biological samples is considered as a rational choice. 3-(2-pyridyl)-5-(2-hydroxyphenyl)-1,2,4-triazole is a highly hydrophobic ligand (logP=3.0±0.1). Dissociation of the protonated nitrogen atom in the pyridine cycle o&f the ligand occurs at pH = 4, рКа1= 3.98±0.05. The pKa2 value is equal to 8.74 ± 0.03 and corresponds to the dissociation of the N-H group of the triazole fragment. The absorption spectrum of the ligand solution in DMSO is characterized by two bands& with maximum at 272 nm and 320 nm due to intraligand [формула] * transitions. The values of the molar absorption coefficient for these bands are 1.18·104 l ·mol-1·cm-1 and 1.36·104 l·mol-1·cm-1, respectively. Two bands at 402 nm and 535 nm are also &observed on the fluorescence spectra of the ligand. The high fluorescence intensity in the long-wavelength region of the spectrum indicates the promising use of this ligand as an analytical reagent at a creation of new fluoresce techniques. 3-(2-pyri&dyl)-5-(2-hydroxyphenyl)-1,2,4-triazole as chelating ligand can form two complex compounds in DMSO solution with composition ML and ML2. Complex formation is accompanied by the appearance of a third absorption band in the visible regions of the spect&rum at 440 nm ([формула] 6,5·103 l ·mol-1·cm-1) due to LMCT transitions. In addition, the complex formation leads to fluorescence quenching. Developed fluorescent techniques for determination of zinc quantities in a sample of hair and in a tablet of &vitamins "Duovit" are characterized by satisfactory precision and accuracy. The range of zinc concentrations determining in the hair sample is 71-286[формула] Sr=0,033 (n=3, P=0.95). The zinc content that was found in the "Duovit" tablet is well corr&elated with the declared content. This indicates the good selectivity of ligand in relation to the accompanying microelements.
