Spectrofluorimetric determination of benzoimidazolic pesticides: effect of p-sulfonatocalix[6]arene and cyclodextrins

Analytica Chimica Acta
Natalia L PacioniA V Veglia

Abstract

The effect of the addition of a macrocyclic host (H) such as p-sulfonatocalix[6]arene (C6S), native and modified cyclodextrins (CDs), on the fluorescence of benzoimidazolic fungicides (P), like Benomyl (BY) and Carbendazim (CZ), has been studied. The fluorescence of BY in water at pH 1.000 and 25.0 degrees C was increased in the presence of C6S, alphaCD and hydroxypropyl-beta-CD (HPCD). The association constants determined by fluorescence enhancement showed weak interactions (K(A) approximately 10(1) to 10(2) M(-1)) between the fungicide with both CDs, whereas they were stronger with C6S (K(A) approximately 10(5) M(-1)). Molecular recognition of BY for C6S was mainly attributed to electrostatic interactions, and for CDs to the hydrophobic effect and hydrogen bond formation. On the other hand, the fluorescent behaviour of CZ in the presence of C6S at pH 6.994 was interpreted as the formation of two complexes with 1:1 (P:H) and 1:2 (P:H(2)) stoichiometry, the latter being less fluorescent than the free analyte. Relative fluorescence quantum yield ratios between the complexed and free BY (phi(P:H)/phi(P)) were 2.00+/-0.05, 1.40+/-0.03 and 2.8+/-0.4 for C6S, alphaCD and HPCD, respectively. The analytical parameters improved in the ...Continue Reading

Citations

Feb 23, 2011·Analytica Chimica Acta·Valeria N Sueldo Occello, Alicia V Veglia
Nov 11, 2008·Carbohydrate Research·Isabelle Mallard-FavierFrançois Delattre
Mar 24, 2012·Chemical Society Reviews·M Teresa AlbeldaHans-Jörg Schneider
May 4, 2021·Frontiers in Chemistry·Mindy Levine
Nov 24, 2018·The Journal of Physical Chemistry. B·Ludovic GarnierPatrice Malfreyt

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