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AZ9RBAYCAN KIMYA JURNALI № 1 2012
UDC 543.4:54.412.2
SPECTROPHOTOMETRIC INVESTIGATION OF COMPEX FORMATION OF CERIUM(III) WITH 1-PHENYL-2,3-DIMETHYLPYRAZOLONE-5-AZO-4-PYROGALLOLE IN THE PRESENCE OF 8-HYDROXYQUINOLINE
S.R.Gadjiyeva, F.E.Huseynov, A.Sh.Efendiyeva, M.T.Akhundova, F.M.Chiragov
Baku State University
[email protected] Received 23.12.2011
Complex formation of cerium(III) with 1-phenyl-2,3-dimethylpyrazolone-5-azo-4-pyrogallole (L) in the presence and absence of 8-hydroxyquinoline (HQ) was investigated. It is revealed that homogeneous CeL and mixed ligand CeL-HQ compounds are formed at pH 6. Ratio of reagents in composition of homogeneous is 1:2 and in different ligand it equals to 1:2:2. The technique for photometric determination of cerium has been worked out in artificial mixture.
Keywords: 1 -phenyl-2,3-dimethylpyrazolone-5-azo-4-pyrogallol, cerium (III), 8-hydroxyquinoline, complex formation, photometric.
It is known that synthesis and the study of analytical means of azoderivatives of pyragollole and the application in photometric determination of elements is up-to-date in analytical chemistry [1]. It is also known, that using of mixed ligand complexes for improvement of analytical parameters of reaction found wide application in practical works [2, 3].
In this article the influence of 8-hydroxyquinoline (HQ) on conditions of complex formation of cerium(III) with 1-phenyl-2,3-dimethylpyrazolone-5-azo-4-pyragallole and analytical characteristics of formed complexes was investigated.
EXPERIMENTAL
110-3 M aqueous-spirit solution of L and 1 • 10-2 M spirit solution of HQ were used. Solution of cerium(III) was prepared from Ce2(CO3)3 by dilution in HCl (1:1) at heating. Solutions of lower concentrations were prepared by subsequent dilution. For keeping up of pH they used acetate-ammonium buffer solution.
Acidity of buffer solutions was measured by ionomer I-130 with glass electrode ESL-43-07, tuned in standard buffer solutions. Optical density of solutions was measured by spectrophotometer Lamda 40 (Perkin Elmer) and photo colorimeter KFK-2MP in ditch with thickness of layer 1 sm.
RESULTS AND DISCUSSION
Determination of Dissociation Constants of Reagent. For determination of dissociation constants of reagent they used pH-meter titration in aqua medium. The volume of 110-3 M titrated solutions is 50 mL. Ionic strength (I = 0.1) was kept up by constant introduction of calculated amount of KCl. Titrant is 210-2 M solution of KOH, free from carbonic acid. For calculation of dissociation constant of reagent they used the equation [4]. According to calculations pK = 6.71±0.02, pK2 = 7.85±0.04, pK3 = 8.83±0.08.
Investigation of Complex Formation of Cerium(III). Investigation of dependence of complex formation on acidity of medium showed that maximum output of binary complex is observed at pH = 6, ^max = 420 nm, and at HQ the mixed ligand compound is formed at pH 6, ^max=442 nm.
Using of saturation curve of 4 10-5 M solution of CeL complex with HQ method of curve's crossing, there was determined stability constant of mixed ligand complex. For this purpose, they found equilibrium concentration (ccompl) of CeL-HQ complex for several points of saturation curve: cconp i = cceL (AA/ AAlim), where AA/ AAlim - ratio of limiting value of difference of optical densities of
different ligand complex's solution at the saturation conditions and solution of complex CeL at cCeL= const. After this the stability constant was calculated by equation
Kn = Ccompl/(cCeL -CcomplXCHQ -nCcompl) [5].
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DETERMINATION OF COMPEX FORMATION OF CERIUM(III) WITH 33
It is known, that the form of reagent in solution depends on acidity of medium. For determination of the forms of reagent responsible for complex formation with cerium, using the equation [6], on the basic of pKi, pK2 and pK3 molar shares of ionic and molecular forms of L were calculated and diagrams of reagent's distribution in solutions were built (Figure).
a, % 100
80 -
60 -
40 -
20
Diagram of distribution of reagent in solution.
5 6 7 8 9 pH
Shows that reactive form of reagent in the presence and absence of HQ is actually H3L and H2L". Ratio of reagents in complexes was established by Starik-Barbanel's method of relative output, by method of dislocation of equilibrium and isomolar series. Molar coefficients of complexe's absorption are calculated from saturation curves [7]. The intervals of concentrations where Beer's law is observed were established (Table 1).
Table 1. Basic photometric characteristics of reactions of cerium (III) with reagents at pH 6
Reagent ^max, nm Ratio Ce:reagent e-10-3 lgK Interval of observation of Ber's law, ^g/mL
L 420 1:2 9.25 5.15±0.02 1.12-11.2
L + HQ 442 1:2:2 12.5 8.24±0.01 1.12-11.2
2,6-dibrome-4-chlorcarboxyarsenazo [8] 630 1:2 160.0 - 0-0.8
0
The influence of foreign ions and masking compounds on complex formation of cerium(III) in the presence and absence of HQ was studied for the determination of selectivity of the reactions.
Determination of Cerium(III) in an Artificial Mixture. There were placed 0.10-0.80 mL of 110-3 M solution of cerium(m), 2.0 mL of 110-3 M solution of HQ and 3.0 mL of 110-3 M solution of reagent in the flask with volume 25 mL for determination of cerium in the presence of 0.5 mL 10-1 M solution of each ion (Ni2+, Cr3+, Mn2+, Mo6+, Zn2+). The solution was diluted till the mark with buffer solution pH 6 and the optical density was measured at 440 nm comparing with HQ solution. Maintenance of cerium(III) in analyzed solutions was determined by graphic curve (Table 2).
Table 2. Results of photometric determination of cerium
Added Ce, ^g Found Ce, ^g St
28.0 28.5 0.01
42.0 41.7 0/02
56.0 55.6 0.01
84.0 83.5 0.02
REFERENCE
1. Гамбаров Д.Г. Дисс. ... докт. хим. наук. Москва: МГУ, 1984. 295 p.
2. Пилипенко А.Т., Тананай М.М. Разнолигандные и разнометалльные комплексы и их применение в аналитической химии. М.: Химия, 1983. 221 р.
3. Саввин С.Б., Чернова Р.К., Штыков С.Н. Поверхностно-активные вещества. М.: Наука, 1991. 251 р.
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S.R.GADJIYEVA et al.
4. Дятлова Н.М., Темкина В.Ю., Колпакова И.Д. Комплексоны. M.: Химия, 1970. 417 p.
5. Проблемы химии и применение ß-дикетонатов металлов / Под ред. Спицина В.И. M.: Наука, 1982.264 p.
6. Дорохова Е.Н., Прохорова Г.Н. Задачи и вопросы по аналитической химии. М.: Мир, 2001. 267 p.
7. Булатов М.Н., Калинкин И.П. Практическое руководство по фотометрическим и спек-трофотометрическим методам анализа. М.: Химия, 1972. 407 р.
8. Li Z., Yang Y., Liu J. et al. // Anal. Lett. 2002. V. 35. P. 1959.
SERÍUMUN(III) 1-FENÍL-2,3-DÍMETÍLPÍRAZOLON-5-AZO-4-PÍROQALLOLLA 8-OKSÍXÍNOLÍN ͧTÍRAKINDA KOMPLEKS OMOLOGOTÍRMOSÍNÍN TODQÍQÍ
S.R.Haciyeva, F.E.Hüseynov, A.§.Ofandiyeva, M.T.Axundova, F.M.£iraqov
8-Oksixinolin i§tirakinda va i§tiraki olmadan seriumun(III) 1-fenil-2,3-dimetilpirazolon-5-azo-piroqallolla (L) kom-pleks amalagatirmasi öyranilmi§dir. Eyniliqandli CeL va müxtalifliqandli CeL-Ox birla§malari pH 6-da amala galir. Qar§iliqli tasirda olan komponenetlarin eyni- (1:2) va müxtalifliqandli (1:2:2) birla§malarda nisbati müayyan edil-mi§dir. Seriumun süni qari§iqda fotometrik tayini metodikasi i§lanilmi§dir.
Agar sözlar: 1-fenil-2,3-dimetilpirazolon-5-azo-piroqallol, serium(III), 8-oksixinolin, komplekssmslsgstirms, fotometrik.
СПЕКТРОФОТОМЕТРИЧЕСКОЕ ИССЛЕДОВАНИЕ КОМПЛЕКСООБРАЗОВАНИЯ ЦЕРИЯ(Ш) С 1-ФЕНИЛ-2,3-ДИМЕТИЛПИРАЗОЛОН-5-АЗО-4-ПИРОГАЛЛОЛОМ В ПРИСУТСТВИИ 8-ОКСИХИНОЛИНА
С.Р.Гаджиева, Ф.Е.Гусейнов, А.Ш.Эфендиева, Н.Т.Ахундова, Ф.М.Чирагов
Изучено комплексообразование церия(Ш) с 1-фенил-2,3-диметилпиразолон-5-азо-4-пирогаллолом (L) в присутствии и отсутствие 8-оксихинолина (Ох). Выявлено, что однородно- CeL и смешанолигандное CeL-Ох соединения образуются при рН 6. Установлено соотношение реагирующих компонентов в составе однородно- (1:2) и смешанолигандного (1:2:2) соединений. Разработана методика фотометрического определения церия в искусственной смеси.
Ключевые слова: 1-фенил-2,3-диметилпиразолон-5-азо-4-пирогаллол, церий(Ш), 8-оксихинолин, комплексообразование, фотометрический.
