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Fluorimetric Detection of Phosphates in Water Using a Disassembly Approach: A Comparison of Fe III ‐, Zn II ‐, Mn II ‐ and Mn III ‐salen Complexes
Author(s) -
Winkler Daniela,
Banke Sophie,
Kurz Philipp
Publication year - 2020
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.202000045
Subject(s) - chemistry , reactivity (psychology) , pyrophosphate , steric effects , inorganic chemistry , selectivity , aqueous solution , crystallography , catalysis , stereochemistry , organic chemistry , medicine , alternative medicine , pathology , enzyme
Details of the reaction sequence used for the fluorimetric detection of phosphates by disassembly of transition metal Schiff base complexes were investigated for [Fe III (salen)(H 2 O)] + , [Zn II (salen)], [Mn II (salen)(H 2 O) 2 ], and [Mn III (salen)(H 2 O)] + . The reactivity of these compounds towards phosphorus oxoanions of differing charge, number of donor atoms and steric hindrance was detected by UV/Vis and fluorescence spectroscopy in both aprotic organic and aqueous media. Selectivity of [Fe III (salen)(H 2 O)] + towards pyrophosphate over all other tested phosphorus‐containing analytes was strongly supported. [Zn II (salen)] showed a faster reactivity but was much less selective. In contrast, [Mn III (salen)(H 2 O)] + proved to be more stable than the iron complex but generally showed little reactivity towards phosphorus oxoanions. The influence of the charge of the central atom was investigated using the Mn II analogue [Mn II (salen)(H 2 O) 2 ]. As expected, the reduced charge resulted in a reactivity comparable to the Zn II complex in organic solution but lead to hydrolysis of the complex in water. Finally, the reaction products of [Fe III (salen)(H 2 O)] + with phosphates were characterized by IR spectroscopy and mass spectrometry, providing further insights into the reaction mechanism of the disassembly process.