Synthesis and Characterization of Electroactive Ferrocene Derivatives: Ferrocenylimidazoquinazoline as a Multichannel Chemosensor Selectively for Hg²⁺ and Pb²⁺ Ions in an Aqueous Environment

Abstract

The synthesis and characterization of ferrocene (Fc) derivatives 4-[2,5-diferrocenyl-4-(4-pyridyl)imidazolidin-1-ylmethyl]pyridine (1), ferrocenylmethylenepyridin-3-ylmethylamine (2), N,N'-bis(ferrocenylmethylene)-2,4,6-trimethylbenzene-1,3-diamine (3), and 6-ferrocenyl-5,6-dihydro[4,5]imidazo[1,2-c]quinazoline (4) have been described. Structures of 1, 2, and 4 have been determined by single-crystal X-ray diffraction analyses. At 25 °C, 1-3 are nonfluorescent, while 4 displays moderate fluorescence and chromogenic, fluorogenic, and electrochemical sensing selectively toward Hg(2+) and Pb(2+) ions. Association constants (K(a)) for Hg(2+) and Pb(2+) have been determined by the Benesi-Hildebrand method. Job's plot analysis supported 1:1 and 1:2 stoichiometries for Hg(2+) and Pb(2+) ions. Cyclic voltammograms of 1-4 exhibited reversible waves corresponding to a ferrocene/ferrocenium couple. The wave associated with 4 (+0.0263 V) exhibited positive (ΔE(pa) = 0.136 V) and negative (ΔE(pa) = 0.025 V) shifts in the presence of Hg(2+) and Pb(2+) ions, respectively. The mode of interaction between metal ions and 4 has been supported by (1)H NMR spectroscopy and mass spectrometry studies and verified by theoretical studies. It presents the first report dealing with ferrocene-substituted quinazoline as a multichannel chemosensor for Hg(2+)/Pb(2+) ions.

Addressing of multiple-metal ions on a single platform

“…Pandey et al [89] recently reported some ferrocene derivatives among which ferrocenylimidazoquinazoline, 70, acted as a multiple-channel chemosensor for Hg 2+ and Pb 2+ ions. The molecule demonstrated vivid responses toward Hg 2+ and Pb 2+ ions in three channels viz.…”

Optical methods for the detection of heavy metal ions

“…101 It was shown that this ligand is suitable for determination of mercury and lead ions in 50% aqueous ethanol. After the addition of Hg 2+ , the almost colourless solution becomes dark-red, while after the addition of Pb 2+ , the solution becomes light-green.…”

Design and synthesis of some imidazolyl derivatives: Photophysical studies and application in detection of anions

“…The limit of detection (LOD) for Fand CNions have been estimated through the fluorescence spectroscopic method, as reported previously [59][60][61][62][63][64][65][66]. The slope of fluorescence curves gave calibration sensitivity (m) 6.03 and 4.27 for Fand CN -, respectively.…”