Chromogenic and fluorogenic sensing of Cu2+ based on coumarin

A new rhodamine-based colorimetric chemosensor for naked-eye detection of Cu(2+) in aqueous solution

A new colorimetric probe 1 based on rhodamine B lactam was developed for naked-eye detection of Cu(2+). The optical feature of 1 for Cu(2+) was investigated by UV-vis absorption spectroscopy. Upon the addition of Cu(2+), the 1 displayed a distinct color change from colorless to pink, which can be directly detected by the naked eye. The stoichiometry of 1 to Cu(2+) complex was found to be 1:1 and the naked-eye detection limit was determined as low as 2 μM. The results suggest that the probe 1 may provide a convenient method for visual detection of Cu(2+) with high sensitivity.

A mitochondria-targeted near-infrared probe for colorimetric and ratiometric fluorescence detection of hypochlorite in living cells

A mitochondria-targeted near-infrared probe for rapid, sensitive and specific detection of hypochlorite with colorimetric and ratiometric fluorescence dual responses.

Fluorescein-N-Methylimidazole Conjugate as Cu(2+) Sensor in Mixed Aqueous Media Through Electron Transfer

A new highly selective, chromogenic, and fluorogenic Cu(2+) chemosensor, fluorescein-N-methylimidazole conjugate 1, and another fluorescein-N-imidazole conjugate 2 were synthesized and investigated by UV-visible and fluorescence spectroscopy. The sensing of Cu(2+) quenches the emission band of 1 at λmax = 525 nm, with an association constant (K a = 1.0 x 10(7) M(-1)) and a stoichiometry of 1:1 in a buffered H2O: MeOH solution (4:1, pH = 7.4). The Cu(2+) detection limit for chemosensor 1 is 37 nM. The presence of the N-methyl group in 1 increased the Cu(2+) binding selectivity, resulting in a stronger binding constant and a broader pH working range (pH 5-10) in comparison to 2. The fluorescence in 1 and 2 is caused by electron transfer phenomenon from the imidazole nitrogen to fluorescein, which is readily inhibited by Cu(2+) binding.

N-(3-Imidazolyl)propyl dansylamide as a selective Hg(2+) sensor in aqueous media through electron transfer

N-Imidazolylpropyl dansylamide 1 was synthesized for the sensing of metal ions and found to be selective and sensitive toward Hg(2+) ions in a PBS-EtOH (1:4, pH=7.4) solution. The sensing ability of probe 1 was examined by UV-Vis, fluorescence, and (1)H NMR spectroscopy. The sensing of Hg(2+) exhibited a quenching of emission band at λmax=515 nm of probe 1, which was associated with quenching of green fluorescence emission under 365 nm illumination. Probe 1 showed a good association constant with Hg(2+) (Ka=6.48×10(4) M(-1)) with a stoichiometry of 1:1 in PBS-EtOH (1:4, pH=7.4) having the lowest detection limit of 1 μM for Hg(2+); on the other hand, probe 2, which has no imidazole moiety, was not able to detect any metal ion. In the case of probe 1, electrons on the imidazole nitrogen are available for electron transfer (ET), which was responsible for its green emission band that was quenched on addition of Hg(2+); this clearly indicates that these electrons were used for the formation of a coordinate bond with Hg(2+) and that ET was switched off.

A novel pyrazole biscoumarin based chemosensors for the selective detection of Cu(2+) and Zn(2+) ions

A novel chemosensor based on pyrazole biscoumarin molecule "4-hydroxy-3-((4-hydroxy-2-oxo-2H-chromen-3-yl)(1,3-diphenyl-1H-pyrazol-4-yl)methyl)-2H-chromen-2-one" (PBC) was synthesized by a simple method. The chemosensing properties of PBC towards transition metal ions like Cu(2+) and Zn(2+) by naked eye, UV-Visible and fluorescence spectroscopic methods were described. The PBC solution with Cu(2+) and Zn(2+) ion showed brown and blue colour respectively. The UV-Visible spectra of PBC with Cu(2+) and Zn(2+) ions exposed their corresponding absorption maxima. Further, the Job's plot method confirmed the 1:1 and 2:1 stoichiometry of the complex formation between the PBC with Cu(2+) and Zn(2+) ions respectively. The fluorescence enhancement of PBC on binding with Cu(2+) and Zn(2+) is due to the inhibition of photo induced electron transfer mechanism.

Optical sensor: a promising strategy for environmental and biomedical monitoring of ionic species

In this review, we cover the recent developments in fluorogenic and chromogenic sensors for Cu²⁺, Fe²⁺/Fe³⁺, Zn²⁺and Hg²⁺.

Synthesis of 4-hydroxyindole fused isocoumarin derivatives and their fluorescence “Turn-off” sensing of Cu(ii) and Fe(iii) ions

A simple and efficient protocol has been developed for the synthesis of 4-hydroxyindole fused isocoumarins from easily available starting materials.

A selectively fluorescein-based colorimetric probe for detecting copper(II) ion

A novel fluorescein derivative 3-bromo-5-methylsalicylaldehyde fluorescein hydrazone (BMSFH) has been synthesized by reacting fluorescein hydrazide with 3-bromo-5-methylsalicylaldehyde and was developed as a new colorimetric probe for detection of Cu(2+). In the presence of Cu(2+) the BMSFH exhibits a rapid color change from colorless to yellow together with an obvious new band appeared at 502nm in the UV-vis absorption spectra. However, other common alkali-, alkaline earth-, transition- and rare earth metal ions induced no or minimal spectral changes. This change is attributed to BMSFH via coordination with Cu(2+) in a 1:1 stoichiometry and this binding to Cu(2+) is reversible, as indicated by the bleaching of the color when the Cu(2+) is extracted with EDTA. Experimental results indicate that the BMSFH can provide a rapid, selective and sensitive response to Cu(2+) with a linear dynamic range 3.0-330μmol/L and can be used as a potential Cu(2+) colorimetric probe in aqueous solution.

A selectively rhodamine-based colorimetric probe for detecting copper(II) ion

A novel rhodamine derivative 3-bromo-5-methylsalicylaldehyde rhodamine B hydrazone (BMSRH) has been synthesized by reacting rhodamine B hydrazide with 3-bromo-5-methylsalicylaldehyde and developed as a new colorimetric probe for the selective and sensitive detection of Cu2+. Addition of Cu2+ to the solution of BMSRH results in a rapid color change from colorless to red together with an obvious new band appeared at 552 nm in the UV-vis absorption spectra. This change is attributed to the spirocycle form of BMSRH opened via coordination with Cu2+ in a 1:1 stoichiometry and their association constant is determined as 3.2×10(4) L mol(-1). Experimental results indicate that the BMSRH can provide a rapid, selective and sensitive response to Cu2+ with a linear dynamic range 0.667-240 μmol/L. Common interferent ions do not show any interference on the Cu2+ determination. It is anticipated that BMSRH can be a good candidate probe and has potential application for Cu2+ determination. The proposed probe exhibits the following advantages: a quick, simple and facile synthesis.

A selectively fluorescein-based colorimetric probe for detecting copper(II) ion

A novel fluorescein derivative furfuraldehyde fluorescein hydrazone (FFH) has been synthesized by reacting fluorescein hydrazide with furfuraldehyde and characterized by (1)H NMR, (13)C NMR, MS and elemental analysis. Addition of Cu(2+) to the solution of FFH results in a rapid color change from colorless to yellow together with an obvious new band appeared at 502 nm in the UV-vis absorption spectra. This change is attributed to the spirocycle form of FFH opened via coordination with Cu(2+) in a 1:1 stoichiometry and their association constant is determined as 6.1×10(4) L mol(-1). Experimental results indicate that the FFH can provide a rapid, selective and sensitive response to Cu(2+) with a linear dynamic range 6.6-330 μmol/L. Common interferent ions do not show any interference on the Cu(2+) determination. It is anticipated that FFH can be a good candidate probe and has potential application for Cu(2+) determination in aqueous solution.

7-Di-ethyl-amino-3-{(E)-4-[(E)-2-(pyridin-4-yl)ethen-yl]styr-yl}-2H-chromen-2-one

In the title coumarin derivative, C28H26N2O2, the coumarin unit is approximately planar, with a maximum deviation of 0.048 (3) Å. The central benzene ring is oriented at dihedral angles of 30.15 (14) and 10.51 (11)°, respectively, to the pyridine ring and coumarin ring system. In the crystal, weak C-H⋯O and C-H⋯N hydrogen bonds and weak C-H⋯π inter-actions link the mol-ecules into a three-dimensional supra-molecular architecture.

Discovery of a novel fluorescent HSP90 inhibitor and its anti-lung cancer effect

A novel fluorescent HSP90 inhibitor with strong growth inhibitory effects on lung cancer cells was developed.

A novel colorimetric and fluorogenic chemosensor for selective detection of Cu2+ ions in mixed aqueous media

A novel and easy-to-synthesize chemosensor (L) was developed for the selective sensing of Cu²⁺ ions in mixed aqueous medium.

A BODIPY derivative as a colorimetric, near-infrared and turn-on chemosensor for Cu2+

A new colorimetric and near-infrared (NIR) fluorescent chemosensor (1) for Cu(2+) based on BODIPY has been synthesized and investigated in this work. 1 Displays a high selectivity for Cu(2+) with about 250-fold enhancement in fluorescence emission intensity and micromolar sensitivity (K(d)=2.8±0.3 μM) in comparison with alkali and alkaline earth metal ions (Na(+), K(+), Mg(2+), Ca(2+)) and other metal ions (Ba(2+), Zn(2+), Cd(2+), Fe(2+), Pb(2+), Ni(2+), Co(2+), Ag(+)) upon excitation at 635 nm in CH(3)CN. Meanwhile, the distinct color changes and rapid switch-on fluorescence also provide 1 as colorimetric senor for Cu(2+).

A DFT study of pyrrole-isoxazole derivatives as chemosensors for fluoride anion

The interactions between chemosensors, 3-amino-5-(4,5,6,7-tetrahydro-1H-indol-2-yl)isoxazole-4-carboxamide (AIC) derivatives, and different anions (F(-) Cl(-), Br(-), AcO(-), and H(2)PO(4) (-)) have been theoretically investigated using DFT approaches. It turned out that the unique selectivity of AIC derivatives for F(-) is ascribed to their ability of deprotonating the host sensors. Frontier molecular orbital (FMO) analyses have shown that the vertical electronic transitions of absorption and emission for the sensing signals are characterized as intramolecular charge transfer (ICT). The study of substituent effects suggests that all the substituted derivatives are expected to be promising candidates for fluoride chemosensors both in UV-vis and fluorescence spectra except for derivative with benzo[d]thieno[3,2-b]thiophene fragment that can serve as ratiometric fluorescent fluoride chemosensor only.