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New dithiacrown–ether butadienyl dyes: synthesis, structure, and complex formation with heavy metal cations
Author(s) -
Vedernikov Artem I.,
Ushakov Evgeny N.,
Kuz'mina Lyudmila G.,
Churakov Andrei V.,
Strelenko Yuri A.,
Wörner Michael,
Braun André M.,
Howard Judith A. K.,
Alfimov Michael V.,
Gromov Sergey P.
Publication year - 2010
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1596
Subject(s) - chemistry , stability constants of complexes , crown ether , acetonitrile , ether , selectivity , metal , medicinal chemistry , stereochemistry , organic chemistry , aqueous solution , ion , catalysis
Benzothiazole type butadienyl dyes containing a dithia‐15‐crown‐5 ( 2a ) or dithia‐18‐crown‐6 ether ( 2b ) moieties were synthesized. The structures of dyes 2a , b and their complexes with Ag + and Pb 2+ were studied by an X‐ray crystallography. It was found that the conformations of dithiacrown–ether moieties of dyes 2a , b are unfavorable for complex formation and change significantly upon binding of Ag + or Pb 2+ . The complexation of 2a , b with Ag + , Cd 2+ , Pb 2+ , and Hg 2+ in water–acetonitrile mixtures with different contents of water ( P W = 0–75%, v/v) was studied by 1 H NMR, UV–Vis spectroscopy, and polarography. In anhydrous acetonitrile, the stability constants of 1:1 complexes change in the sequence Cd 2+ < Pb 2+ ≤ Ag + << Hg 2+ in the case of 2a and in the sequence Cd 2+ < Ag + < Pb 2+ << Hg 2+ in the case of 2b . As P W increases, the thermodynamic stability of Ag + complexes increases. The opposite effect is observed for the complexes with Cd 2+ , Pb 2+ , and Hg 2+ . When P W ∼ 50%, the stability constants of complexes with Cd 2+ and Pb 2+ become too small to be measured. The selectivity of ligands 2a , b toward Hg 2+ versus Ag + is very high at any P W values (selectivity coefficients > 10 4 ). The complexation of 2a , b with Hg 2+ at P W ≤ 50% is accompanied by a substantial hypsochromic effect. This allows dithiacrown‐containing butadienyl dyes to be used as selective optical molecular sensors for heavy metal ions, in particular, in aqueous solutions. Copyright © 2009 John Wiley & Sons, Ltd.