A Selective Redox and Chromogenic Probe for Hg(II) in Aqueous Environment Based on a Ferrocene−Azaquinoxaline Dyad

Abstract

A new chemosensor molecule 4 based on a ferrocene-azaquinoxaline dyad effectively recognizes Hg(2+) in an aqueous environment as well as Pb(2+) and Zn(2+) metal cations in CH(3)CN solution through three different channels. Upon recognition, an anodic shift of the ferrocene/ferrocenium oxidation peaks and a progressive red shift (Deltalambda = 112-40 nm) of the low energy band, in their absorption spectra, is produced. These changes in the absorption spectra are accompanied by color changes from orange to deep green, for Hg(2+), and to purple in the cases of Pb(2+) and Zn(2+). Remarkably, the redox and colorimetric responses toward Hg(2+) are preserved in the presence of water (CH(3)CN/H(2)O, 3/7). The emission spectrum of 4 in CH(3)CN (lambda(exc) = 270 nm) undergoes important chelation enhancement of fluorescence (CHEF) in the presence of Hg(2+) (CHEF = 204), Pb(2+) (CHEF = 90), and Zn(2+) (CHEF = 184) metal cations. Along with the spectroscopic data, the combined (1)H NMR data of the complexes and the theoretical calculation suggest the proposed bridging coordination modes.

Fluorescent and colorimetric sensors for environmental mercury detection

“…The naphthalenediimide-based sensor 89 was designed, based on the TICT mechanism, for the recognition of intracellular Hg 2+ in living HeLa cells. 110 Hg 2+ addition induces the formation of a 1:1 complex and progressive enhancement of the intensity of the fluorescence emission band at 620 nm to about 204-fold. Because of TICT, free 89 is almost nonluminescent in solution.…”

A new ferrocene–anthracene dyad for dual-signaling sensing of Cu(II) and Hg(II)

“…In addition, we compared the present proposed sensor with those previously reported fluorophore-appended ferrocenes for determination of Hg 2+ (Table 1) [62][63][64][65][66][67]. As can be seen, the proposed sensor results seem good with respect to the limit of detection (LOD) and working medium.…”

Synthetic Methodology for Asymmetric Ferrocene Derived Bio-conjugate Systems via Solid Phase Resin-based Methodology

“…[30][31][32][33][34][35][36][37][38] Ferrocene is an organometallic molecule that is a gold standard for electrochemistry, which makes it an excellent choice for integration into electrochemical biosensors. Ferrocene-based redox active species have already garnered considerable attention due to their small size, good stability, convenient synthetic access, easy chemical modification, relative lipophilicity, and ease of redox tuning.…”

“…3,[30][31][32][33][34][35][36][37][38][39][40][41][42] Small molecules based on the ferrocene core have been used extensively as detectors of metal ions and small molecules. [32][33][34][35][36][37][38]43 Systems targeting larger species such as biomolecules have utilized the attachment of large antibodies or immunoglobulins to ferrocene derivatives that have been embedded onto an electrochemical surface. 1,3,39,44 In each case, the potential and current intensity of the Fe III /Fe II redox couple was altered upon molecular coupling, thus producing a new spectroscopic handle indicating the presence of the analyte molecule.…”