An easy prepared dual-channel chemosensor for selective and instant detection of fluoride based on double Schiff-base

A series of benzothiazole-based Schiff bases for the colorimetric sensing of fluoride and acetate ions: acetate-induced turn-on fluorescence for selectivity

Benzothiazole-based Schiff bases show colorimetric sensing of fluoride and acetate ions. It also exhibits selective acetate-induced turn-on fluorescence.

A new colorimetric and fluorescent probe based on Rhodamine B hydrazone derivatives for cyanide and Cu2+ in aqueous media and its application in real life

A simple selective colorimetric and fluorimetric chemosensor RD based on Rhodamine B hydrazone derivatives was designed and synthesized, which showed both colorimetric and fluorescence responses for cyanide and Cu²⁺ in aqueous solution with specific selectivity and high sensitivity. In the presence of cyanide, the sensor exhibited a visible color change from colorless to pale yellow by naked-eyes and rapidly produced a strong yellow fluorescence in aqueous solution. The detection limit on fluorescence response of RD sensor to CN^- is down to 3.54×10^-7M. In addition, compared to other metal ions such as Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Cr³⁺, Zn²⁺ and Mg²⁺ in aqueous solutions, RD could show both colorimetric and fluorescence responses rapidly for Cu²⁺. Notably, this sensor can be used as a molecular switch controlled by CN^- and H⁺ cyclically. Test strips based on RD were fabricated that could be used as a convenient and efficient CN^- and Cu²⁺ test kits. RD could detect cyanide in germinated potato, bitter almond and tap water. This chemosensor enabled detection of two ions, which do not need to rely on two different sensors.

A selective chemosensor for fluoride ion and its interaction with Calf Thymus DNA

The amido-Schiff base 1 (N¹, N³-bis (2-nitrobenzylidene)benzene-1,3-dicabohydrazide) containing a CONH group and CHN linkage has been synthesized by the condensation between isophthalic acid dihydrazide and o-nitrobenzaldehyde. This molecule can act as a fluoride ion sensor with high selectivity and sensitivity. Presence of nitro group in the phenyl ring may be responsible for the detection of fluoride ion visually with a dramatic color change from colorless to deep red in aqueous dimethyl sulphoxide solution. This Schiff base can be used as test kit for sensing of fluoride ion in the solid state. Compound 1 can detect fluoride also in commercially available toothpaste. As the compound has adequate solubility in DMSO-water mixture (7:93, v/v) and having some hydrogen bond donor and acceptor centers, we have investigated its nature of binding with Calf Thymus-DNA (CT-DNA) using theoretical molecular modelling and other experimental methods like UV-vis spectroscopy, circular dichroic and thermal melting studies. Thermodynamic parameters have been obtained using the well known Van't Hoff's equation. From both theoretical and experimental findings it has been observed that it can interact effectively with CT-DNA with binding energy -7.55kcal/mol to -7.50kcal/mol.

A new unsymmetrical azine derivative based on coumarin group as dual-modal sensor for CN- and fluorescent "OFF-ON" for Zn2

A simple chemosensor YS based on coumarin group was designed and synthesized. Its structure was determined by single crystal X-ray diffraction analysis. In the presence of cyanide the sensor showed an immediate visible change in color from colorless to pale yellow by naked-eyes and produced a strong blue fluorescence rapidly in DMSO/H₂O (3:7, v/v). The detection limit on fluorescence response of the sensor to CN^- is down to 1.69×10^-7M. In addition YS could show fluorescence turn-on response rapidly for Zn²⁺ over other metals ions such as Fe³⁺, Hg²⁺, Ag⁺, Ca²⁺, Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Pb²⁺, Cr³⁺ and Mg²⁺ in aqueous solutions. Notably, this sensor served as a molecular switch, which was controlled by Zn²⁺ and EDTA cyclically. Test strips based on YS were fabricated, which could act as a convenient and efficient CN^- and Zn²⁺ test kit. This chemosensor could achieve the detection of two ions, which need not depend on two different sensors.

A novel dual-channel chemosensor for CN− based on rhodamine B hydrazide derivatives and its application in bitter almond

We successfully designed and synthesized a novel chemosensor PW bearing rhodamine B hydrazide and 8-formyl-7-hydroxyl-4-methylcoumarin, which displayed both colorimetric and “turn-on” fluorescence responses for CN⁻ in DMSO/H₂O (1 : 1, v/v, pH = 7.20) solution.