A new thio-Schiff base fluorophore with copper ion sensing, DNA binding and nuclease activity

Study on the photochromism, photochromic fluorescence switch, fluorescent and colorimetric sensing for Cu2+ of naphthopyran-diaminomaleonitrile dyad and recognition Cu2+ in living cells

A well-designed naphthopyran-diaminomaleonitrile dyad (sensor 1) has been synthesized successfully, its molecular structure was well characterized by NMR and mass spectrometry. Sensor 1 exhibits excellent photochromic and photochromic fluorescence switch performance with reversible color change and good fatigue resistance upon alternating ultraviolet irradiation and thermal bleaching. In addition, sensor 1 displayed excellent fluorescent and colorimetric sensing ability towards Cu²⁺ ions with high selectivity and sensitivity. The addition of 5.0 equiv. of Cu²⁺ ions into sensor 1 (1 × 10^-5) in CH₃CN solution significantly quenched the fluorescence of sensor 1 by 80.0%. Furthermore, the addition of Cu²⁺ ions also caused the complete disappearance of the absorbance band at 350-450 nm in absorbance spectra of sensor 1 and accompanied by the distinct color change form yellow to colorless. Job's plot, mass spectrometry, ¹H NMR titration and DFT calculations proved that sensing performance was attributed to the formation of 1:1 sensor 1-Cu²⁺complexes. Sensor 1 can monitor the existence of Cu²⁺ ions in living cells via the fluorescence images. Sensor 1 showed great potential applications as chemosensor and photochromic materials.

Ultrasensitive and highly selective detection of Cu2+ ions based on a new carbazole-Schiff

A new chemosensor for Cu²⁺ based on Schiff base with high sensitivity and selectivity was designed and synthesized. The fluorescence intensity of the chemosensor in CH₃CN solution was enhanced 160-fold after the addition of 10 equiv. Cu²⁺ over other metal ions. In addition, it also facilitates colorimetric detection for Cu²⁺ in CH₃CN solution. The chemosensor displayed low detection limit and fast response time to Cu²⁺.

A new multi-analyte fluorogenic sensor for efficient detection of Al3+and Zn2+ions based on ESIPT and CHEF features

The synthesized ESIPT based fluorogenic chemosensor, H₂L, selectively detects Zn²⁺and Al³⁺in a MeOH–H₂O (4/1, v/v, pH = 7.2) medium.

New approach for the quantification of metallic species in healthcare products based on optical switching of a Schiff base possessing ONO donor set

A new method is reported for the quantification of some metallic components of healthcare products utilizing a Schiff base chelator derived from 2-hydroxyacetophenone and ethanolamine. The Schiff base chelator recognizes some metallic species such as iron, copper and zinc (important components of some healthcare products), and cadmium (common contaminant in healthcare products) giving colorimetric/fluorimetric response. It coordinates with Fe²⁺/Fe³⁺ and Cu²⁺ ions via ONO donor set and switches the colour to bright red, green and orange, respectively. Similarly, it switches 'ON' a fluorometric response when coordinates with Zn²⁺ and Cd²⁺ ions. In the present approach, detailed studies on the colorimetric and fluorimetric response of ONO Schiff base is investigated in detail. The Job plot for the complexation of ONO switch with various metal ions suggested formation of 1:1 (metal-chelator) complex with Fe²⁺, Fe³⁺, and Cu²⁺ while 1:2 (metal-chelator) for Zn²⁺ and Cd²⁺ ions. The limit of detection, limit of quantification are 6.73, 18.0, 25.0, 0.65, 1.10μM and 27.0, 72.0, 100.0, 2.60 and 4.40μM for Fe²⁺, Fe³⁺, Cu²⁺, Zn²⁺ and Cd²⁺ ions, respectively. Under the optimized conditions, chelator was used for the quantification of important metals present in healthcare products via direct dissolution and furnace treatment during sample preparation. The results were found precise and accurate for both sample preparation techniques using the developed method.