Simple Fluorescent Chemosensor Research Articles

A simple salicylaldehyde-bearing pyrazine as a turn-on fluorescent chemosensor for Al3+ and Zn2+ recognition and its applications

Abstract A simple fluorescent chemosensor, 5-(diethylamino)-2-((2-(pyrazin-2-yl) hydrazono)methyl)phenol, has been synthesized by Schiff-base condensation reaction. The chemosensor exhibited highly selective and sensitive “off-on” fluorescent responses toward Al3+ and Zn2+ but the signal of fluorescence emission varies. The detection limits were found to be 2.33 × 10−7 M for Al3+ and 1.68 × 10−7 M for Zn2+, respectively. The binding mechanisms between chemosensor and Al3+ or Zn2+ ions were supported by Job′s, 1H NMR, Fourier transform infrared spectra, and MS experiments. The sensing behavior was also studied with molecular logic functions of OR, AND, and NOT gates. In addition, the chemosensor was able to detect Al3+ and Zn2+ by producing distinct color changes observed by the naked eye on sensor-coated swabs. Moreover, the chemosensor was successfully applied to effectively detect Al3+ and Zn2+ in actual water and drug samples.

Experimental and Theoretical Studies of the Pyrazoline Derivative 5-(4-methylphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4,5-dihydro-1H-Pyrazole and its Application for Selective Detection of Cd2+ ion as Fluorescent Sensor.

A simple fluorescent chemosensor 5-(4-methylphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4, 5-dihydro-1H-pyrazole (PY) has been synthesized for the detection of Cd2+ ion.The fluorescent probe PY shows high selectivity for Cd2+in the presence of othermetal ions (Co2+, Cu2+, Hg2+, Mn2+, Zn2+, Fe3+, Pb2+, Ni2+, and Al3+). The fluorescence intensity of the PY has been strongly quenched with increasing concentration of Cd2+ (0-0.9μM)via photoinduced electron transfer mechanism. The binding constant of Cd2+ to PY for the 1:1 complex isfound to be 5.3 × 105M-1with a detection limit of 0.09μM. The chemosensor was successfully applied for determination of Cd2+ in different water samples (tap, river, and bottled water) showing good recovery values in the range of 94.8-101.7% with RSD less than 3%. Density functional theory (DFT) calculations were also performed to investigate electronic and spectral characteristics which are quite agreeable with the experimental value. The results show that the synthesized fluorescent chemosensor shows good selectivity towards Cd2+ and can be readily applied for the detection of Cd2+ in real samples including water samples.

Benzimidazole-functionalized fluorescent probe for rapid detection of 2,4,6-trinitrophenol and Ag+ in semiaqueous medium

In this study, a simple fluorescent chemosensor with good fluorescence properties was synthesized, and was used to develop a sensitive and selective sensor, for the determination of 2,4,6-trinitrophenol (TNP) and Ag+ in THF/H2O medium, based on the fluorescence quenching mechanism. Fluorescence quenching experiments revealed that the fluorescence intensities of the resulted probe were linear with the concentrations of TNP and Ag+ in the concentration range of 3.0?5.0 and 2.0?5.0 ?mol dm-3, with the detection limit of 1.36 and 0.82 ?mol dm-3, respectively. At the same time, accompanied with fluorescent color change under 365 nm UV light irradiation. This has demonstrated that the compound can act as a potential candidate for a ?naked-eye? rapidly detector for Ag+ and TNP in soils and aquatic systems.

Application of Imidazole Derivative for Fluorescent Detection and Determination of Cu(II) in Aqueous and Biological Media

A simple fluorescent chemosensor 2-(furan-2-yl)-4,5-diphenyl-1H-imidazole (P1) based on an imidazole furan conjugate has been designed, synthesized and characterized. Fluorimetric studies on chemosensor P1 showed excellent selectivity toward Cu2+ ions over other metal ions in aqueous media through a “turn on−off” process. A possible reverse photoinduced electron transfer mechanism is proposed. The viability of P1 to Cu2+ has been demonstrated by live cell imaging.

A Simple Fluorescent Chemosensor for Detection of Zinc Ions in Some Real Samples and Intracellular Imaging in Living Cells

A new designed fluorescent chemosensor TYMN ((E)-1-((thiazol-2-ylimino)methyl)naphthalen-2-ol) for highly sensitive and selective tracing of trace amount of Zn2+ ions in some real samples was synthesized and characterized. The sensor TYMN can detect Zn2+ ions via fluorescence enhancement with a high selectivity over a wide range of metal ions, especially Cd2+. The sensor showed large fluorescence enhancement upon complexation with Zn2+ and simultaneous color change from yellow to orange. The limit of detection was analyzed to be 0.0311 μM with a linear dynamic range 0.1-1.0 μM. The sensor could work in a pH span of 5.0-8.0. Based on the physicochemical and analytical methods like electrospray ionization (ESI)-mass, Job plot, 1H nuclear magnetic resonance (NMR) and theoretical calculations, the detection mechanism for Zn2+ was explained based on restriction of internal charge transfer (ICT) mechanism. TYMN sensor was potentially utilized for Zn2+ ions concentration evaluation in some real samples. Fluorescence microscopy experiments revealed that probe TYMN may have application as a fluorophore to detect the Zn2+ in living cells.

A new fluorescent probe based on imidazole[2,1-b]benzothiazole for sensitive and selective detection of Cu2+

Abstract A simple fluorescent chemosensor WS1 (N'-[(Z)-1H-indazol-3-ylmethylidene]imidazo [2,1-b] [1,3]benzothiazole-2-carbohydrazide) based on imidazole [2,1-b]benzothiazole was designed and synthesized. The probe showed specific recognition towards Cu2+ through colorimetric and “turn-off” fluorescence response in MeOH/H2O (9:1 V/V) buffer solution (10 mM Tris, pH = 7.4) with detection limit of 4.32 × 10−8 M. In addition, WS1 was a reversible fluorescence probe for the detection of Cu2+, the fluorescence intensity recovered to the similar state of free WS1 as PPi was added. And it showed a favorable potency for actual water monitoring. The proposed binding mode of WS1 with Cu2+ was verified by DFT calculation using Gaussian 09.

A highly sensitive turn-on fluorescent chemosensor for recognition of Zn(II) ions and its application in live cells imaging

A novel and simple fluorescent chemosensor, DH, was synthesized. As designed, DH displayed excellent selectivity exhibiting a “turn-on” response for Zn2+ over other relevant metal ions based on PET mechanism in 100% aqueous media, and the binding constant of Zn2+ binding to DH was calculated to be 7.27 × 108 M−2. Importantly, DH exhibited high sensitivity as a Zn2+ fluorescent chemosensor with a limit of detection (LOD) of 19.25 nM, which is lower than WHO guidelines (76.0 μM). Moreover, the 2:1 stoichiometry between the chemosensor DH and Zn2+ was verified by Job's plot, fluorescent titration and high resolution mass spectroscopy. In addition, the recognition process of DH toward Zn2+ was chemically reversible and recyclable by adding Na2EDTA. Moreover, due to its good biocompatibility and low cytotoxicity, DH was successfully applied to the fluorescence imaging of Zn2+ and Na2EDTA in living HK2 cells.

Naphthalene-derived Al3+-selective fluorescent chemosensor based on PET and ESIPT in aqueous solution

A simple fluorescent chemosensor HL based on naphthalene with high selectivity and sensitivity towards Al3+ over other commonly coexisting metal cations in fully aqueous solution to enhance the potential applications of the fluorescent chemosensor was developed. HL exhibited a significant fluorescence enhancement at 475 nm in the presence of Al3+ over other competitive metal ions with a low detection limit of 0.43 μM due to the inhibition of the photo induced electron transfer (PET) and the excited-state intramolecular proton transfer (ESIPT). The 1:1 binding stoichiometry between HL and Al3+ was corroborated by the Job plot and the ESI-MS spectrum. Importantly, the reversible recognition process of HL to Al3+ will make HL could be used circularly and repeatedly in practical applications by addition of Na2EDTA. In addition, the binding behavior and sensing mechanism of HL to Al3+ were illustrated in detail by the 1H NMR titration experiment.

A simple benzimidazole quinoline-conjugate fluorescent chemosensor for highly selective detection of Ag+

A novel and simple fluorescent chemosensor (L), N-((1H-benzo[d]imidazol-2-yl)methyl)quinoline-2-carboxamide, based on quinoline benzimidazole scaffold was synthesized successfully, which had a ‘turn-on’ effect for Ag+ detection in methanol/Tris buffer(1:1, v/v, pH=7.35) and exhibited a strong fluorescence emission at 357 nm (λex=300 nm). The chemosensor had high sensitivity and selectivity for Ag+ even in the presence of other metal ions with the detection limit of 4.4×10−7 M, which reached the standard of World Health Organization (WHO) for drinking water (5.0×10−7 M). The mechanism of the interaction between the sensor and Ag+ was investigated in detail through NMR and MALDI Mass spectra analysis.

A fluorescent chemosensor for Al3+ based on julolidine and tryptophan moieties

A new and simple fluorescent chemosensor 1, based on julolidine and tryptophan moieties, has been synthesized and characterized. The sensor 1 displayed a selective and sensitive detecting ability for aluminum (III) ion by ‘OFF–ON’ fluorescent response in aqueous solution. This sensing mechanism might be due to the inhibition of CN isomerization, and the activation of chelation enhanced fluorescence (CHEF). This sensing mechanism of 1 for Al3+ was supported by theoretical calculations. Moreover, sensor 1 had a low detection limit (6.4 μM), which is below than the WHO recommendation level (7.41 μM) for drinking water. Importantly, the chemosensor 1 could be applied to living cells to detect Al3+. Therefore, the sensor 1 can be employed as a practical fluorescent chemosensor for recognition of Al3+ in aqueous solution.

A highly selective fluorescent chemosensor for Hg2+ based on rhodamine B and its application as a molecular logic gate

A novel and simple fluorescent chemosensor based on rhodamine (R-2) is designed and synthesized to detect Hg2+. Probe R-2 exhibits high selectivity and sensitivity for sensing Hg2+ with a detection limit at 10(-8) M level, and displays a significant color change from colorless to pink color in the presence of Hg2+. About a 400-fold increase in fluorescence emission intensity is observed upon binding excess Hg2+ in 50% H2O/CH3CN HEPES buffer at pH 7.00. The titration results show a 1:1 complex formation between R-2 and Hg2+. The reversibility of chemosensor R-2 is verified through its spectral response toward Hg2+ and I- titration experiments. Using Hg2+ and I- as chemical inputs and the fluorescence intensity signal as outputs, R-2 can be utilized as an INHIBIT logic gate at molecular level. (C) 2013 Elsevier Ltd. All rights reserved.

Reversible “off–on” fluorescent chemosensor for Hg 2+ based on rhodamine derivative

A novel and simple fluorescent chemosensor based on rhodamine was designed and synthesized to detect Hg 2+ with high selectivity. The structure of chemosensor 1 was characterized by IR, 1H NMR, and HRMS spectroscopies. Chemosensor 1 exhibited distinct fluorescent and colorimetric changes toward Hg 2+ in an ethanol/water (80/20, v/v) solution, which resulted in the formation of 1/Hg 2+ complex with the Hg 2+-induced ring opening of the spirolactam ring in rhodamine. The reversibility of chemosensor 1 was verified through its spectral response toward Hg 2+ ions and TBAI (tetrabutylammonium iodide) titration experiments.

A Simple Fluorescent Chemosensor for Mg2+ Based on C=N Isomerization with Highly Selectivity and Sensitivity

Abstract A simple fluorescent chemosensor based on naphthalene has been prepared. It was shown to be selective for Mg2+ in acetonitrile based on C=N isomerization. The free ligand showed quite weak fluorescence emission due to the isomerization of C=N double bond in the excited state, however, after addition of Mg2+, fluorescence emission results in a prominent fluorescence enhancement.

Fluorescent Probe for Oxalic Acid: Design, Synthesis, and Evaluation.

Center for Integrated Molecular Systems and Department of Chemistry, Division of Molecular and Life Sciences,Pohang University of Science and Technology, Pohang 790-784, KoreaReceived August 4, 2004A novel-type of structurally simple fluorescent chemosensor for oxalic acid was designed, synthesized, andevaluated to show that it detects oxalic acid in methanol with high selectivity over other anions including mono-and dibasic carboxylic acids.Key Words : Chemosensor, Oxalic acid, Photoinduced electron transfer, Cyclen, Isothermal titration calorimetryIntroductionMost of chemosensors are constructed by linkingcovalently a signaling unit to a receptor that recognizes andbinds an analyte molecule.

Fluorescent Probe for Oxalic Acid: Design, Synthesis, and Evaluation

Center for Integrated Molecular Systems and Department of Chemistry, Division of Molecular and Life Sciences,Pohang University of Science and Technology, Pohang 790-784, KoreaReceived August 4, 2004A novel-type of structurally simple fluorescent chemosensor for oxalic acid was designed, synthesized, andevaluated to show that it detects oxalic acid in methanol with high selectivity over other anions including mono-and dibasic carboxylic acids.Key Words : Chemosensor, Oxalic acid, Photoinduced electron transfer, Cyclen, Isothermal titration calorimetryIntroductionMost of chemosensors are constructed by linkingcovalently a signaling unit to a receptor that recognizes andbinds an analyte molecule.

A highly selective fluorescent chemosensor for lead ions.

A simple fluorescent chemosensor 1 exhibits a 40-fold fluorescence enhancement upon addition of lead ion and yet is insensitive to most of univalent and divalent metal ions. The high affinity of 1 toward Pb2+ presumably results from the cooperative binding behaviors of two potential metal binding sites: the dicarbonyl and the 15-monoazacrown-5 ether.