Selective Fluorescent Sensor For Hg2 Research Articles

2,3-Dihydro-Quinazolin-4(1H)-One as a Fluorescent Sensor for Hg2+ Ion and its Docking Studies in Cancer Treatment

Abstract The 2,3-dihydro-quinazolin-4(1H)-one was synthesised via the deployment of SBA-Pr-SO3H and its application was explored as a highly selective fluorescent sensor for Hg2+ ion; fluorescence intensity was decreased selectively by Hg2+ ions. Furthermore, this compound also indicated for its superb anti-interference ability among other ions. It is important to mention that this compound could be employed to detect a very low amount of Hg2+ ions, which are highly toxic and general contaminants. The docking study shows that the molecule, 2,3-dihydro-quinazolin-4(1H)-one, is a good inhibitor for the 5ACC enzyme.

A novel triazene-based cadmium metal–organic framework as a selective fluorescent sensor for Hg2+

A new cadmium metal–organic framework (Cd-MOF) has been synthesized by one-pot reaction between 5,5′-(triaz-1-ene-1,3-diyl)diisophthalic acid (H4TEDA) and cadmium acetate. Interestingly, the uncoordinated triazene groups locate in the channel of Cd-MOF. Moreover, the compound exhibits good luminescent property. Benefitting from the porosity, uncoordinated triazene group and luminescence property, Cd-MOF displays high selective response for Hg2+, which makes it as a potential sensor for detecting the toxic metal ions.

1,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ Ions.

We report here the synthesis of a 1,3-alternate calix[4]arene 8, with bis-pyrazolylmethylpyrenes on the one end and bis-triazolylmethylphenyls on the other end, as a homoditropic fluorescent sensor for both Hg2+ and Ag+ ions. Calix[4]arene 3, with lower-rim bis-pyrazolylmethylpyrenes in cone conformation, was also synthesized as a control compound. UV-Vis and fluorescence spectra were used for metal ions screening, and we found that both ligands 8 and 3 showed strong excimer emission of pyrenes when they are as a free ligand in CHCl3/MeOH (v/v, 3:1) solution; however, they both showed a high selectivity toward Hg2+ and Ag+ ions with strong fluorescence quenching and yet with different binding ratios. The fluorescence of ligand 8 was strongly quenched by Hg2+ but was only partially quenched by Ag+ ions; however, the fluorescence of ligand 3 was strongly quenched by Hg2+, Ag+, and Cu2+ ions. Job plot experiments showed that ligand 8 formed a 1:2 complex with both Hg2+ and Ag+ ions; ligand 3 formed a 1:1 complex with Hg2+, but it formed a 2:3 complex with Ag+. The binding constant of ligand 3 with Hg2+ and Ag+ ions was determined by the Benesi-Hildebrand plot of UV-vis titration experiments to be 2.99 × 103 and 3.83 × 103 M−1, respectively, while the association constant of ligand 8 with Hg2+ and Ag+ was determined by Hill plot to be 1.46 × 1012 and 9.24 × 1011 M−2, respectively. Ligand 8 forms a strong complex with either two Hg2+ or two Ag+ ions using both the upper and lower rims of the 1,3-alternate calix[4]arene as the binding pockets; hence, it represents one of the highly selective fluorescent sensors for the homoditropic sensing of Hg2+ and Ag+ ions.

Reusable highly sensitive and selective fluorescent sensor for Hg2+ detection in water based on a thermoresponsive copolymer

A copolymer poly(NIPAM-co-RD) consisting of N-isopropylacrylamide (NIPAM) and N-tripodal rhodamine 6G units (RD) as the thermoresponsive and sensing parts, respectively, has been prepared. At room temperature, the copolymer is fully dissolved in water and it could be used as a highly sensitive and selective fluorescent sensor for Hg2+ in a wide range of pH from 5.0 to 10.0. The non-fluorescent copolymer showed a significant fluorescence enhancement in the presence of Hg2+ over other competitive metal ions. It works based on the Hg2+ induced ring-opening of the rhodamine units. The detection limit was as low as 2.25×10−8M. Upon heating above the lower critical solution temperature (LCST), the copolymer may collapse and form aggregates, therefore the copolymer containing Hg2+ could be separated from water by centrifugation at high temperature. In addition, the separated copolymer with Hg2+ could be treated by sodium sulfide, and the original copolymer was successfully regenerated and then reused for further Hg2+ sensing.

Highly selective fluorescent sensor for Hg2+ ion based on a novel rhodamine B derivative

A highly selective fluorescent sensor (L1) based on a novel rhodamine B derivative was designed, and its recognition mechanism for Hg2+ was studied using fluorescence spectroscopy in methanol–water solution. The results showed that L1 was highly selective for recognizing Hg2+, and that other metal ions did not interfere with this recognition. A good linear relationship was shown between the relative fluorescence intensity of L1 and the concentration of Hg2+ within the range of 4–80μM, with a detection limit of 0.19μM. Job's plot method indicated 1:1 L1-to-Hg2+ stoichiometry in the complex. The mechanism of L1 recognition for Hg2+can be explained by the crystal structure of L2, which was the product of L1 reacting with Hg2+.

Sequential logic operations with a molecular keypad lock with four inputs and dual fluorescence outputs.

A novel coumarin-rhodamine conjugate was prepared, and its metal binding properties were studied by UV/Vis and fluorescence spectroscopy. The conjugate serves as a ratiometric and highly selective fluorescent sensor for Hg(2+) ions. Its metal-responsive spectral properties were utilized to construct a molecular keypad lock with four inputs and dual fluorescence outputs. The complexity of this molecular logic network can greatly enhance the security level of this device.

Sequential Logic Operations with a Molecular Keypad Lock with Four Inputs and Dual Fluorescence Outputs

AbstractA novel coumarin–rhodamine conjugate was prepared, and its metal binding properties were studied by UV/Vis and fluorescence spectroscopy. The conjugate serves as a ratiometric and highly selective fluorescent sensor for Hg2+ ions. Its metal‐responsive spectral properties were utilized to construct a molecular keypad lock with four inputs and dual fluorescence outputs. The complexity of this molecular logic network can greatly enhance the security level of this device.

A water-soluble highly sensitive and selective fluorescent sensor for Hg2+ based on 2-(2-(8-hydroxyquinolin)-yl)benzimidazole via ligand-to-metal charge transfer (LMCT)

A water-soluble fluorescent sensor (L) based on 2-(2-(8-hydroxyquinolin)-yl)benzimidazole has been synthesized and characterized. Sensor L displays highly selective and sensitive recognition of Hg2+ with a fluorescence “ON–OFF” response in buffered aqueous solution (1% dimethyl sulfoxide (DMSO), Tris–HCl 10 mM, pH = 7.4). X-ray crystal structure of the L–Hg2+ complex reveals that the oxygen and nitrogen atoms of 8-hydroxyquinoline and the imine N atom of the benzimidazole unit (N1) bind Hg2+ through a 1 : 1 binding stoichiometry. The fluorescence quenching mechanism is qualitatively evaluated by quantum chemical calculations which show that the fluorescence quenching phenomenon is caused by ligand-to-metal charge transfer (LMCT) in the excited state.

A selective fluorescent sensor for Hg2+ based on covalently immobilized naphthalimide derivative

In this work, a selective fluorescent sensor for Hg2+ detection in aqueous solution, which contains a naphthalimide derivative covalently grafted to the glass surface, was developed. To fabricate the sensor, the naphthalimide derivative (compound 1) with a terminal double bond was prepared and photo-copolymerized with 2-hydroxyethyl methacrylate (HEMA) on the glass surface treated with a silanizing agent. Upon binding mercuric ions in 0.05mol/L Tris/HCl (pH 7.01) at 25°C, the resulting optical sensor undergoes fluorescence enhancement. Thus, the proposed sensor with visible excitation can behave as a fluorescent sensor for the selective detection of Hg2+. The fluorescence enhancement was induced by a photo-induced electron transfer (PET) inhibition process. In addition, the proposed sensor showed satisfactory selectivity, reproducibility and response time. The sensing membrane possesses a relatively long lifetime of at least 2 months. The chemosensor can be applied to the quantification of Hg2+ with a linear range covering from 6.0×10–6 to 2.0×10−4M and a detection limit of 2.0×10−6M. The determination of Hg2+ in river water samples shows satisfactory results.

A selective “turn-on” fluorescent sensor for Hg2+ based on “reactive” 7-hydroxycoumarin compound

A simple 7-hydroxycoumarin-based compound L1 was rationally designed and synthesized behaving as a highly selective fluorescent sensor for Hg2+ in aqueous media. It shows selective and “turn-on” fluorescence upon addition of Hg2+. Fluorescence titration and 1H NMR investigation reveal that the fluorescence enhancement of L1 upon Hg2+ addition is promoted by Hg2+-induced cyclization of L1 to a more rigid dihydrobenzofuran derivative.

A highly selective fluorescent sensor for Hg2+ based on the water-soluble poly(p-phenyleneethynylene)

The conjugated polymer P-1 could be synthesized by the polymerization of 4,7-diethynyl-benzo[2,1,3]thiadiazole (M-1) and 1,4-bis[3′-(N,N-diethylamino)-1′-oxapropyl]-2,5-diiodobenzene (M-2) via Pd-catalyzed Sonogashira reaction. The water-soluble conjugated polyelectrolyte P-2 could be obtained by the reaction of P-1 with ethyl bromide. Both P-1 and P-2 can emit orange fluorescence. The responsive optical properties of P-1 and P-2 on Hg2+ were investigated by fluorescence spectra. Hg2+ can lead to nearly complete fluorescence quenching of P-1. On the contrary, Hg2+ can show the most pronounced fluorescence enhancement response of P-2 in aqueous solution without interference from those coexistent ions, such as K+, Mg2+, Pb2+, Co2+, Ni2+, Ag+, Cd2+, Cu2+, Fe3+ and Zn2+. The results also exhibit that this kind of water-soluble conjugated polyelectrolyte can be used as a highly sensitive and selective fluorescence sensor for Hg2+ detection in water.

A thioether-rich crown-based highly selective fluorescent sensor for Hg2+ and Ag+ in aqueous solution

A new fluorescent sensor 1, based on the naphthalimide chromophore and thioether-rich crown receptor, exhibited dual signaling behaviors for Hg(2+) and Ag(+) in aqueous solution. Upon addition of Hg(2+), the fluorescence intensity enhanced in a linear fashion with a quantum yield increase of about 5-fold. Moreover, with the 1-Hg(2+) complex, Ag(+) was easily recognized by a marked fluorescence quenching. The living cells image experiments demonstrate the value of sensor 1 in fluorescent visualization of Hg(2+) ions in biological systems.