Spectrophotometric Investigation of Iron(III)-N-Phenylcin-namohydroxamic Acid System
作者:
Aberra Fura,
BhagwanSingh Chandravanshi,
期刊:
Analytical Letters
(Taylor Available online 1987)
卷期:
Volume 20,
issue 5
页码: 689-715
ISSN:0003-2719
年代: 1987
DOI:10.1080/00032718708062922
出版商: Taylor & Francis Group
关键词: Iron(III) complexes;isobestic point;stability constant
数据来源: Taylor
摘要:
N-Phenylcinnamohydroxamic acid, PCHA, was found to react with iron (III) to form complex species of different colour depending upon the reaction environment. The reaction conditions for the formation of the complex species were studied in aqueous-ethanolic medium. The general spectral properties of the species were investigated. The absorption curves were found to have two isobestic points. The number and composition of the complexes were determined and found to have composition 1:1, 1:2, 1:3 (Fe: PCHA). The wavelengths of the maximum absorbances were figured out to be 535, 495, and 445 nm for the I, II, and III complex species, respectively. It was verified that the Beer's law holds for these complexes at all wavelengths, and for the mixtures at the wavelengths of the isobestic points in a wide range of pH. The stepwise stability constants have been determined by the method of isobestic point and found to be log K1= 11.55, log K2= 10.11, and log Kg3= 7.44 for the I, II, and III complex species, respectively. The distribution diagrams (nomograms) of the complex species as a function of pH were constructed and the molar extinction coefficients of the three consecutive complexes have also been determined.
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