Turn-on Fluorescent Chemosensor Research Articles

A highly sensitive turn-on fluorescent chemosensor for recognition of Zn2 + and Hg2 + and applications

A fluorescence probe has been designed and synthesized, and applied with a combined theoretical and experimental study. Research suggests that the probe can be used to sense Zn2+ and Hg2+ through selective turn-on fluorescence responses in the aqueous HEPES buffer (0.05M, pH=7.4). The limit of detection (LOD) were determined as 1.46×10−7M (Zn2+) and 2.50×10−7M (Hg2+). Moreover, based on DFT, the geometry optimizations of probe 1, [1-Hg2+] complex and [1-Zn2+] complex were carried out using the Gaussian 09 program, in which the B3LYP function was used. The electronic properties of free probe 1 and the metal complexes were studied based on the Natural Bond Orbital (NBO) analyses. The probe 1 has also been successfully applied to detection of Zn2+ and Hg2+ in living cells.

A fluorescent sensor for Al3+ based on a photochromic diarylethene with a hydrazinobenzothiazole Schiff base unit

A new fluorescent turn-on chemosensor for Al3+ based on a diarylethene unit was designed and synthesized. Photochromism, fluorescence switch, and metal ion recognition behaviors of this diarylethene derivative were investigated by absorption and fluorescence emission spectra. It shows an outstanding fluorometric sensing ability toward Al3+ ion, and the detection limit was measured to be 9.3×10−8molL−1 via fluorescence methods. Based on these interesting properties, a combinational logic circuit was constructed successfully.

A dual responsive colorimetric and fluorescent reversible turn-on chemosensor for iron (Fe3+): Computational and spectroscopic investigations

Herein, we report a highly selective dual responsive chemosensor for detecting iron ion. The structural characterization of synthesized compounds was investigated on the basis of UV–vis, FTIR, 1NMR, 13NMR and Mass spectral data. The sensitivity and selectivity of RDFB toward Fe3+ among different metal ions was examined by absorption, fluorescence, FTIR and mass spectral studies. Complexing with Fe3+ ion leads to spirolactam ring opening of RDFB and consequently causes a color variation from colorless to red. Fe3+-specific binding to RDFB afford a 53-fold enhancement in fluorescence intensity and strong absorption in the visible range. The 1:1 binding mode was proposed on the basis of absorption, FTIR and MS studies. The HOMO and LUMO energy gap for RDFB and RDFB-Fe3+ complex were found to be 3.782eV and 1.875eV suggesting that the interaction of Fe3+ to RDFB reduces the HOMO-LUMO energy gap of the complex and stabilizes the system. The association constant of newly synthesized compound to the receptor is found to be 1.13×105M−1 which further implying the potential of RDFB to acts as a selective chemosensor for Fe3+ ions. Furthermore the reversibility of complexation of RDFB to Fe3+ was also studied by conducting experiments against EDTA.

The chromogenic and fluorescent sensing properties for a water soluble polymeric chemosensor bearing rhodamine ethanediamine moieties with oxethyl (OCH2CH2) as a spacer

The water-soluble copolymer, poly(AM-ARBEE) has been prepared by free radical precipitation copolymerization of N−acryl−(2−oxyethyl) ethylenediamine−N′−(rhodamine B−yl) ethylenediamine (ARBEE) and hydrophilic comonomer (acrylamide, AM) and was characterized by FTIR and 1H NMR. The viscosity average molecular weight Mη of poly(AM-ARBEE) was with (7.07×103gmol−1). The poly(AM-ARBEE) was a selective turn-on fluorescent and chromogenic chemosensor for Cr3+, Fe3+, Hg2+ and Al3+ over other metal ions. Titration curves of Cr3+, Fe3+, Hg2+ and Al3+ was constructed using rapid, cheap and widely available techniques of fluorescence spectroscopies. Furthermore, a colorimetric response from the polymeric chemosensor permitted the detection of Cr3+, Fe3+, Hg2+ and Al3+ by naked-eye due to the development of a purple color when these cations interacted with the copolymer in aqueous media.

A new macrocyclic ligand as a turn-on fluorescent chemosensor for the recognition of Pb2+ions

The chemosensor L has a detection limit of 9.63 nM for Pb2+in an acetonitrile/H2O (9 : 1, v/v) mixture.

2-Hydroxy-naphthyl functionalized mesoporous silica for fluorescence sensing and removal of aluminum ions.

Mesoporous silica functionalized with a 2-hydroxy-naphthyl moiety has been synthesized and characterized by standard techniques like powder X-ray diffraction, N2 adsorption/desorption studies, transmission electron microscopy and spectral studies like FT-IR, UV-visible, fluorescence and 13C and 29Si solid state NMR. The functionalized silica material showed significant enhancement in its emission intensity in the presence of Al3+ ions whereas other metal ions could not bring about any increase in its emission intensity. They either quench the emission or do not alter the intensity significantly making the functionalized material a fluorescence chemosensor for Al3+. The sensitivity of the probe towards Al3+ has been determined to be high with a low limit of detection value. As functionalized silica is not soluble in common solvents, it has been effectively used to bind and remove Al3+ from a solution. Theoretical calculations on a model system have been performed to investigate the electronic spectral transitions.

A turn-on fluorescent chemosensor based on acylhydrazone for sensing of Mg2+ with a low detection limit

A novel highly selective chemosensor for Mg2+ ions based on the naphthalene group as the fluorophore has been designed and synthesized, which shows a fluorescence turn-on response from colorless to green for Mg2+ ions in DMSO–H2O solutions.

A red fluorescent turn-on chemosensor for Al3+based on a dimethoxy triphenylamine benzothiadiazole derivative with aggregation-induced emission

A red fluorescent turn-on chemosensor TB-COOH for Al3+was developed. The dye showed excellent AIE and biocompatibility properties, in which imaging detection and real-time monitoring of Al3+in living HeLa cells were successfully achieved.

A Turn-On Fluorescent Sensor for Selective and Sensitive Detection of Alkaline Phosphatase Activity with Gold Nanoclusters Based on Inner Filter Effect.

In this work, a novel approach for simple and sensitive determination of alkaline phosphatase (ALP) is developed on the basis of an inner filter effect of p-nitrophenylphosphate (PNPP) on the fluorescence of gold nanoclusters (AuNCs). AuNCs with a high quantum yield of 12% were synthesized by one-pot strategy and were directly applied as fluorescent substance. When AuNCs were mixed with PNPP, the fluorescence of the AuNCs was remarkably quenched or was decreased via the inner filter effect since the absorption spectrum of PNPP overlaps well with the excitation spectrum of the AuNCs. While in the presence of ALP, PNPP was catalytically hydrolyzed into p-nitrophenol, which has different absorption characteristics from those of PNPP, resulting in the recovery of the AuNCs fluorescence. Thus, a novel "turn-on" fluorescent sensor for detecting ALP was established with a detection limit as low as 0.002 U/L (signal-to-noise ratio of 3). The turn-on fluorescent sensor exhibits many merits such as high sensitivity, excellent selectivity, and high signal output because of the low background signals. In addition, the developed sensing method was successfully applied to investigate ALP inhibitors and ALP determination in serum samples. A good linear relationship was obtained in the range from 0.02 to 50 U/L, and satisfactory recoveries at four spiking levels of ALP ranged from 95% to 106% with precision below 5%. The very simple sensing approach proposed here should promote the development of fluorescence turn-on chemosensors for chemo/biodetection.

A simple highly sensitive and selective turn-on fluorescent chemosensor for the recognition of Pb2+

A simple highly sensitive and selective turn-on fluorescent chemosensor L based on bis-Schiff-base for Pb2+ ions was synthesized and characterized by spectroscopic techniques. L having high binding affinity towards Pb2+ ions of 2.10×104M−1 selectively detects Pb2+ ions with almost no interference among various competitive ions by a 11-fold fluorescent enhancement in CH3CN/H2O (95:5, v/v) solution over a wide pH range. Moreover, sensor L displayed a lower detection limit of 3.80×10−7M, which is low enough for sensing sub-millimolar concentration of Pb2+ encountered practically.

Novel fluorescent cyanide-selective chemosensor based on a functionalised pillar[5]arene copper(II) complex

As a novel macrocyclic host, pillar[5]arene can selectively recognise guest molecules in organic solvents. In this study, a fluorescent chemosensor composed of a functionalised-pillar[5]arene and Cu2+ metal complex (PN–Cu), which shows good selectivity for CN− anions, has been designed and synthesised. Complexation between PN–Cu and anions has been probed by means of various fluorescence-based methods. PN–Cu, as a turn-on fluorescence chemosensor showed high selectivity towards CN− ions in comparison to other anions, and its detection limit for CN− was calculated as 9.03 × 10−7 M. The PN–Cu sensor can serve as a recyclable component in sensing materials. Moreover, the interaction between the singly functionalised pillar[5]arene and Cu2+ has been probed through various tests. Based on the remarkable selectivity of the chemosensor PN–Cu, we propose that it might be used as a potential material for CN− recognition.

1,8-Naphthalimide-based turn-on fluorescent chemosensor for Cu2+ and its application in bioimaging

Afluorescent chemosensor based on 1,8-naphthalimidewas synthesized for the specific detection of Cu2+. The presence of Cu2+ can induce a large blue shift in emission, which yield a naked-eye visible color change from yellow to blue. Other metal ions including heavy and transition metal ions have no effect on the response of the sensor to Cu2+, and the response to Cu2+ is applicable over a wide pH range. In addition, the chemosensor has been used for imaging of Cu2+ in living Hela cells with satisfying results.

A simple fluorescence turn-on chemosensor based on Schiff-base for Hg2+-selective detection

A simple and effective Schiff-base fluorescent chemosensor L was synthesized, which showed highly selective and sensitive detection of Hg2+ ions in CH3CN/H2O (9:1, v/v) solution over a wide pH range. Sensor L exhibited a specific ‘turn-on’ fluorescent response to Hg2+ with a low detection limit of 2.268×10–8M. The complex solution of L with Hg2+ ion exhibited reversibility with EDTA and regenerated free ligand for further Hg2+ sensing. The results implied that sensor L could effectively act as Hg2+ sensor in aqueous CH3CN media.

A novel diarylethene-based fluorescent switch with a carboxamidoquinoline unit for sensing of Zn(II) ion

Abstract An asymmetrical diarylethene was designed and synthesized as a ratiometric and fluorescent turn-on chemosensor for Zn 2+ by conjugating diarylethene bromide with 2-amino- N -(quinolin-8-yl)acetamide. The diarylethene was highly selective toward Zn 2+ ion with obvious fluorescence change. When triggered by Zn 2+ ion, the diarylethene displayed a remarkable red-shift of fluorescence emission (100 nm) and an obvious increase in fluorescence intensity at 530 nm with a concomitant color change (dark to bright green). Job’s plot and electrospray ionization mass spectrometry analysis implied that the diarylethene bound to Zn 2+ with a binding stoichiometry of 2:1. Additionally, the logic gate based on Zn 2+ /EDTA and UV/vis titration has also been described.

Fluorescence sensor for sequential detection of zinc and phosphate ions

A new, highly selective turn-on fluorescent chemosensor based on 2-(2′-tosylamidophenyl)thiazole (1) for the detection of zinc and phosphate ions in ethanol was synthesized and characterized. Sensor 1 showed a high selectivity for zinc compared to other cations and sequentially detected hydrogen pyrophosphate and hydrogen phosphate. The fluorescence mechanism can be explained by two different mechanisms: (i) the inhibition of excited-state intramolecular proton transfer (ESIPT) and (ii) chelation-induced enhanced fluorescence by binding with Zn2+. The sequential detection of phosphate anions was achieved by the quenching and subsequent revival of ESIPT.

A fluorescence turn-on chemosensor for hydrogen sulfate anion based on quinoline and naphthalimide

A new fluorescence turn-on chemosensor 1 based on quinoline and naphthalimide was prepared and its anion sensing toward various anions behavior was explored in this paper. Sensor 1 exhibited a highly selective fluorescent response toward HSO4− with an 8-fold fluorescence intensity enhancement in the presence of 10equiv. of HSO4− in DMSO-H2O (1/1, v/v) solution. The sensor also displayed high sensitivity to hydrogen sulfate and the detection limit was calculated to be 7.79×10−7M. The sensing mechanism has been suggested to proceed via a hydrolysis process of the Schiff base group. The hydrolysis product has been isolated and further identified by 1H NMR and MS.

A novel colorimetric and turn-on fluorescent chemosensor for iron(III) ion detection and its application to cellular imaging

A novel rhodamine-based dual probe Rh-2 for trivalent ferric ions (Fe3+) was successfully designed and synthesized, which exhibited a highly sensitive and selective recognition towards Fe3+ with an enhanced fluorescence emission in methanol-water media (v/v=7/3, pH=7.2). The probe Rh-2 could be applied to the determination of Fe3+ with a linear range covering from 3.0×10−7 to 1.4×10−5M and a detection limit of 1.24×10−8M. Meanwhile, the binding ratio of Rh-2 and Fe3+ was found to be 1:1. Most importantly, the fluorescence and color signal changes of the Rh-2 solution were specific to Fe3+ over other commonly coexistent metal ions. Moreover, the probe Rh-2 has been used to image Fe3+ in living cells with satisfying results.

A highly selective colorimetric and fluorescent turn-on chemosensor for Al3 + based on naphthalimide derivative

A new chemosensor L based on the naphthalimide moiety was synthesized and characterized. L exhibited the high selectivity and sensitivity for Al3+ in CH3OH, along with colorimetric and fluorometric dual-signaling responses based on the joint contribution of the ICT and CHEF processes. A 1:1 stoichiometry for the L-Al3+ complex was formed with an association constant of 7.6×104M−1, and the limit of detection for Al3+ was determined as 6.9μM. In addition, L was successfully applied to the determination of Al3+ in real water samples.

A turn-on fluorescent chemosensor selectively detects cyanide in pure water and food sample

A turn-on fluorescent chemosensor (H-1) for cyanide anions based on dihydroxy phenazine was designed and synthesised. The sensor H-1 exhibits high sensitivity and good selectivity for cyanide in pure water. The CN− response mechanism involves a hydrogen bonding and deprotonation process in the sensor, which induced prominent fluorescence enhancement. The detection limit of the sensor toward CN− is 5.65×10−7M, and other anions had nearly no influence on the probing behavior. In addition, test strips based on the sensor were fabricated, which also exhibit a good selectivity to CN− in water. Notably, this sensor was successfully applied to detect CN− in food samples, which proves a very simple and selective platform for on-site monitoring of CN− in agriculture samples.

A turn-on fluorescent chemosensor for Zn2+ ion: X-ray structure and application in cell imaging study

The selective fluorescence zinc(II) sensing properties of a Schiff-base compound, 2-methoxy-6-(2-morpholinoethyliminomethyl)phenol (HL) have been explored. The emission intensity of HL in the presence of one equivalent of Zn2+ ion increases by about 25 times. Several other metal ions, except Cd2+ and Ni2+, have not been able to increase the emission intensity of HL significantly. The quantum yield and life-time of HL have also been increased in the presence of Zn2+ ions. The enhancement in fluorescence intensity of HL is mainly due to the restriction of ESIPT, CHEF and PET on complex formation. HL forms a complex with Zn2+ in 1:1 ratio as evidenced by Job's plot analysis and X-ray single crystal structure determination. Some theoretical calculations have been performed to get a better view on the nature of the observed electronic transitions. The probe has been applied for imaging of DLD-1, human colorectal adenocarcinoma cell.