Dual chemosensing properties of new ferrocene-based receptors towards fluoride and copper(II) ions

Fluorescent chemosensors containing redox-active ferrocene: a review

The redox-active ferrocene containing two cyclopentadienyl rings and iron was extensively employed in the field of sensing, catalysis, medicine, biotechnology etc., due to the structural stability, solubility in common solvents and easy structural modification to make a wide variety of ferrocene derivatives. The ferrocene moiety can be linked suitably with fluoro-chromogenic units and applied for the multichannel (fluorescent, chromogenic and redox) sensing of various bioactive and toxic analytes. This review was narrated to compile some important ferrocene based fluorescent chemosensors developed for the detection of metal ions, anions and neutral analytes. The analytical novelty and sensing mechanisms of the summarized chemosensors are discussed to open new scopes for future research.

A novel high performance nano chemosensor for copper (II) ion based on an ultrasound-assisted synthesized diphenylamine-based Schiff base: Design, fabrication and density functional theory calculations

A novel high selective colorimetric chemosensor was introduced based on a nano diphenyl-based Schiff base (H₂L), 2,2'-((1E,1'E)-(((hexylazanediyl)bis(4,1-phenylene))bis(methanylylidene))bis(azanylylidene))bis(4-methylphenol) that synthesized using sonochemical method. H₂L was characterized by FT-IR, MS, TGA, ¹H NMR, ¹³C NMR, SEM and elemental analysis techniques, then fabricated as the portable strips for sensing copper (II) ions in aqueous media. The binding interaction between H₂L and various metal ions was investigated by UV-Vis spectroscopic that showed favorable coordination toward Cu²⁺ ion. H₂L exhibited binding-induced color changes from yellow to pink and practically no interference in the presence of other metal ions, i.e., Cr²⁺, Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Pb²⁺, Mg²⁺ and Ca²⁺. The chemsensor showd the color change from yellow to pink in presence of copper (II) ion in aqueous media due to binging of H₂L and Cu (II). This sensor can determine the copper (II) at in the rang of 7.5 × 10^-8-1.8 × 10^-5 mol L^-1 with a correlation equation: Absorbance = 0.0450[Cu²⁺] × 10^-6 + 0.71 and R² = 0.975 and low detection limit of 1.89 × 10^-8 mol L^-1. Density functional theory (DFT) calculations were carried out at the B3LYP levels of theory with B3LYP/6-311+G(d,p) and LANL2DZ/6-311+G(d,p) basis sets for chemosensor and its copper complex respectively. The optimized geometry, harmonic vibrational frequencies, ¹H NMR and ¹³C NMR chemical, Molecular orbital (M.O.), Mulliken population analysis (MPA), contour of Electrostatic Potential (ESP) and Molecular Electrostatic Potential (MEP) map of H₂L were calculated which show good agreement with behavior of sensor for detection of Cu²⁺ ion.

Design, synthesis, characterization and cation sensing behavior of amino-naphthoquinone receptor: Selective colorimetric sensing of Cu(II) ion in nearly aqueous solution with mimicking logic gate operation

An amino-naphthoquione receptor (R1) has been rationally designed, synthesized and characterized using ¹H and ¹³C NMR, LCMS and single crystal X-ray diffraction studies. The receptor exhibits an instantaneous colour change from yellow to blue selectively with Cu(II) ions in water-DMF (98:2% v/v) medium. The results of UV-Vis and fluorescence spectral studies indicates that the mechanism of sensing involves formation of a 1:1 complex between R1 and Cu(II) ion. The proposed mechanism has been confirmed through product analysis using FT-IR, UV-Vis, EPR and HRMS studies in addition to magnetic moment and elemental analysis measurements. The formed [Cu(R1)Cl₂] possess a square planar geometry. The binding constant for the interaction of Cu(II) ion with the present unsubstituted quinone is found to be relatively higher than that with quinones containing electron withdrawing chlorine atom and electron releasing methyl group reported in literature. The detection limit of Cu(II) ion in aqueous solution by R1 is observed to be 8.7nM. The detection of Cu(II) ion by R1 in aqueous solution produces remarkable changes in the electronic and fluorescence spectra, which is applied to construct logic gate at molecular level.

Highly selective fluorescence sensors for the fluoride anion based on carboxylate-bridged diiron complexes

The diiron–sulfur clusters bearing urea and anthracene units showed rapid and selective recognition for the fluoride ion.

A new dual fluorogenic and chromogenic "turn-on" chemosensor for Cu²⁺/F⁻ ions

Turn "off-on" chemosensor 2-(-2-((3',6'-bis(diethylamino)-3-oxospiro[isoindoline-1,9'-xanthen]-2-yl)imino)ethylidene)-N-phenylhydrazine-1-carbothioamide (RBS) was designed and synthesized. Using the naked eye, RBS showed favorable observation characteristics with both Cu(2+) and F(-) ions. The various modes of sensitivity shown by RBS toward the Cu(2+) and F(-) ions were investigated by spectral techniques, including UV-Vis, fluorescence and (1)H NMR spectroscopy. The Job's plot indicated the formation of 1:1 complex between RBS and Cu(2+)/F(-). The binding constant of the RBS-guest(-) complexes were found to be 1.3×10(4) and 6.2×10(3)M(-1) for the RBS-Cu(2+) and RBS-F(-), respectively.

Chromogenic naked-eye detection of copper ion and fluoride

Colorimetric chemosensor was reported for detection of Cu²⁺ and F⁻via the color change from colorless to yellow and to orange.