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

New pyrazole porphyrin conjugates were successfully prepared from a reaction of beta-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+, Na+, K+, Mg2+, Ca2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+, and Cr3+ was studied by spectrophotometric and spectrofluorimetric titrations. In the presence of Zn2+, 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 Cu2+ and Ag+, and in poly(methyl methacrylate) doped films with promising results for Zn2+ detection.