Highly Selective and Reversible Optical, Colorimetric, and Electrochemical Detection of Mercury(II) by Amphiphilic Ruthenium Complexes Anchored onto Mesoporous Oxide Films

Abstract

The colorimetric, fluorimetric, and electrochemical detection of mercury ions by functionalized ruthenium sensitizers in aqueous and non‐aqueous solutions and on anchored TiO2 films are investigated. Mercury ions coordinate reversibly to the ruthenium sensitizers, inducing a color change and increasing the phosphorescence intensity significantly. The electrochemical data of the adsorbed sensitizer on TiO2 films show a reversible couple, owing to the percolation through electronic couplings between –NCS ligands of neighboring molecules; upon exposure to a Hg2+‐containing solution, the electrical signal is appreciably reduced. The detection limit for mercury(II) ions using UV‐vis spectroscopy in homogeneous aqueous solutions is estimated to be ∼ 20 ppb. The results presented herein have important implications in the development of reversible colorimetric, fluorimetric, and electrochemical on–off sensors based on nanocrystalline semiconductor films for the simple, swift, and selective detection of mercury ions in solution.

A colorimetric probe for the detection of Ni2+ in water based on Ag-Cu alloy nanoparticles hosted in electrospun nanofibres

“…If Ag and Cu ions are reduced simultaneously in the same solution, Ag-Cu alloy nanoparticles are expected to form. The alloy formation could be concluded from the fact that the optical absorption spectrum showed only one plasmon band, in agreement with literature reports (Mulvaney, 1996;Papavassiliou, 1976;Torigoe et al, 1993). Two bands would be expected if there was a mixture of Ag and Cu nanoparticles.…”

“…2 inset). Silver NPs alone in the polymeric solution had a strong surface plasmon resonance peak at 408 nm, while that of the Ag-Cu alloy NPs was broad and redshifted to 424 nm (Mulvaney, 1996). In addition, the plasmon resonance absorption band of Ag NPs was stronger and sharper in comparison with that of Cu nanoparticles (at 551 nm), and occurred at longer wavelengths (Fig.…”

“…Hence, there is a need to develop simple, reliable methods that are cheap, sensitive, selective as well as capable of use by non-skilled personnel, preferably in the field. Recently, colorimetric sensing of metal ions has been shown to be a less labour-intensive alternative to techniques based on fluorescence (Nazeeruddin et al, 2006). It is well known that solid materials that change colour upon recognition of macromolecules are widely accepted for fingerprinting and for conducting pregnancy tests at home (Prabhakaran et al, 2007).…”

Highly Efficient Nanoporous TiO2‐Polythiophene Hybrid Solar Cells Based on Interfacial Modification Using a Metal‐Free Organic Dye

“…A similar blue-shift was reported by treatment of N719-modified TiO 2 films with metal ions. [31] After the same film was rinsed with CH 3 CN, the resulting absorption spectrum (curve 4) was similar to curve 3. When the Li-salt and TBP treatmenst and washing cycle were repeated on the same film, there was no significant variation in the absorption spectrum of N719, according to curves 5 and 6.…”

Spiropyran-based optical approaches for mercury ion sensing: Improving sensitivity and selectivity via cooperative ligation interactions using cysteine

“…Alternatively, optical probes using organic fluorophores [6,7], semiconduct [8,9], DNAzymes [10,11], and oligonucleotides [12] have been developed for simple and rapid detection of Hg 2+ . Recently, much effort has been made on exploring Hg 2+ colorimetric detection [13][14][15][16][17]. This approach possesses the advantage of the convenience and aesthetic appeal of a visual assay.…”