Synthesis, Spectroscopy Studies, and Theoretical Calculations
of New Fluorescent Probes Based on Pyrazole Containing Porphyrins
for Zn(II), Cd(II), and Hg(II) Optical Detection
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Abstract
New
pyrazole–porphyrin conjugates were successfully prepared from
a reaction of β-porphyrin–chalcone derivatives with phenylhydrazine
in acetic acid followed by an oxidative step. This fast and efficient
synthetic approach provided the expected compounds in yields up to
82%. The sensing ability of the new porphyrin–pyrazole derivatives
to detect the metal ions Ag<sup>+</sup>, Na<sup>+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, Ca<sup>2+</sup>, Ni<sup>2+</sup>, Cu<sup>2+</sup>, Zn<sup>2+</sup>, Cd<sup>2+</sup>, Hg<sup>2+</sup>, Pb<sup>2+</sup>, and Cr<sup>3+</sup> was studied by spectrophotometric and spectrofluorimetric
titrations. In the presence of Zn<sup>2+</sup>, the conjugates exhibit
changes in the emission spectra that are desired for a ratiometric-type
fluoroionophoric detection probe. The studies were extended to gas
phase, where the pyrazole–porphyrin conjugates show ability
to sense metal ions with high selectivity toward Cu<sup>2+</sup> and
Ag<sup>+</sup>, and in poly(methyl methacrylate) doped films with
promising results for Zn<sup>2+</sup> detection