Development of highly selective chemosensor for Al3+: Effect of substituent and biological application (original) (raw)
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Imine linked fluorescent chemosensor for Al3+ and resultant complex as a chemosensor for HSO4− anion
Inorganic Chemistry Communications, 2012
Imine linked chemosensor has been synthesized and examined for cation recognition properties. The sensor shows strong affinity for Al 3+ over other cations such as Na + , K + , Mg 2+ , Ca 2+ , Ba 2+ , Sr 2+ , Cr 3+ , Mn 2+ , Fe 3+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Ag + , Hg 2+ , Pb 2+ , Zr 4+ , Th 4+ and VO 4+ . The resultant Al 3+ complex has been synthesized and characterized on the basis of elemental analysis, mass spectra, and IR spectra. The recognition behavior of this complex was tested towards various anions and the complex has offered an interesting opportunity for the ratiometric determination of HSO 4 − in DMF/H 2 O (7:3, v/v) solvent system. This is the first Al 3+ complex used for the ratiometric determination of HSO 4 − in semi-aqueous medium.
A novel, optical rhodamine-2-chloronicotinaldehyde-type chemosensor (R6CN) was designed, synthesized and characterized as a reversible switch. R6CN displayed high selectivity toward Al 3+ from various metal ions, including Al 3+ , Li + , Na + , K + , Cs + , Mg 2+ , Ca 2+ , Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , Ag + , Cd 2+ , Hg 2+ , Pb 2+ and the resultant complex [R6CN-Al 3+ ]. The ring-opening mechanism of the rhodamine spirolactam was induced by Al 3+ binding, and the 1:1 stoichiometric structure between R6CN and Al 3+ was adequately supported by the Job-plot evaluation, optical titration, FT-IR and 1 H NMR results. Theoretical calculations and modeling simulations were performed using Material Studio 4.3 suite (VAMP), and the results supported the formation of a 1:1 complex between R6CN and Al 3+. The fluorescence quantum yield of R6CN-Al 3+ (˚ f = 92.33%) was very high compared to that of the bare ligand. The detection limit for Al 3+ was 4.28 × 10 −9 M, and a significant color change from almost colorless to pale-pink occurred in the presence of Al 3+. In turn, the R6CN-Al 3+ complex acted as a selective chemosensor toward N 3 − among various anions, including F − , Cl − , Br − , I − , NO 3 − , CH 3 COO − , ClO 4 − , CN − , SCN − , HSO 4 − , HPO 4 − and PF 6 − , in acetonitrile media. Moreover, the R6CN-Al 3+ complex also exhibited a high selectivity and sensitivity toward the azide anion upon the addition of Al 3+ , and the color reversed back to colorless when the two ions were present together in solution. At last, R6CN was productively applied to the PEGDMA polymer to sense Al 3+ ions, which was analyzed using FT-IR, fluorescence confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) images.
We have synthesized a novel 2-chloronicotinaldehyde-functionalized rhodamine B derivative (RBCN)that acts as an “OFF–ON” chemosensor. RBCN specifically binds Al3+in the presence of a large excessof competing metal ions (Li+, Na+, K+, Cs+, Mg2+, Ca2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Ag+, Cd2+, Hg2+andPb2+) and exhibits visible changes in its electronic and fluorescent spectral behavior. These spectralchanges are significant in the visible region of the spectrum and thus enable detection with the nakedeye. Upon coordination with Al3+, the promoted ring opening of the rhodamine spirolactam ring in theRBCN chemosensor evokes a fluorescence turn-on response via the chelation-enhanced fluorescence pro-cess. The probe exhibited good brightness and fluorescence enhancement in which the lower detectionlimit for Al3+was 2.86 × 10−8M. The ring-opening mechanism of the rhodamine spirolactam inducedby Al3+binding and the 1:1 stoichiometric structure between RBCN and Al3+were supported by Job’splot evaluation, UV–vis, fluorescence titrations, FT-IR and1H NMR spectroscopic studies. Finally, theo-retical calculations and modeling simulations were conducted using Material Studio 4.3 suite to simulatethe formation of a 1:1 complex between RBCN and Al3+. However, the fluorescence and colorimetricresponse of the RBCN-Al3+complex was quenched by the addition of azide (N3−) anion, which abstractsthe Al3+ion from the complex and turns off the sensor, confirming that the recognition process isreversible.
Colorimetric and optical discrimination of halides by a simple chemosensor
A thiophene-based tripodal copper(II) complex has been synthesized as a new colorimetric and optical chemosensor for naked-eye discrimination of halides in acetonitrile and an acetonitrile–water mixture. The binding interactions of the new receptor with several anions were analyzed by UV-Vis titrations, electrospray ionization mass spectrometric (ESI-MS) experiments and density functional theory (DFT) calculations. The results from UV-Vis titrations indicate that the coordinative unsaturated copper(II) complex strongly binds a halide at its vacant copper(II) centre via a metal–ligand bond forming a 1 : 1 complex, exhibiting binding affinities in the order of fluoride > chloride > bromide > iodide. The interactions of the receptor with halides were further confirmed by ESI-MS, showing a distinct signal corresponding to a 1 : 1 complex for each halide, suggesting that the noncovalent interactions also exist in the gas phase. In addition, time-dependent DFT (TD-DFT) calculations were also carried out to understand the excited-state properties of the chemosensor complexes. A detailed analysis of the TD-DFT calculations shows a consistent red-shift in the first optically-allowed transition, consistent with the observed colorimetric experiments.
A new rhodamine-6G phenylthiourea derivative (L1) condensed product was developed as a fluores-cent and colorimetric dual chemosensor in acetonitrile with more selective towards Hg2+and F−ions.Hg2+-promoted spirolactam ring opening of the rhodamine moiety induced urea formation through thediphenylcarbodiimide intermediate from the thiourea moiety. It demonstrates high selectivity for sensingHg2+with about 700-fold enhancement in fluorescence emission intensity and micromolar sensitivity(limit of detection 4.52 × 10−7M) in comparison with other various metal ions. Hg2+ions coordinatedreversibly to L1, forming a 1:2 metal–ligand complex. The thiourea moiety provided an anion bindingsite, and the rhodamine system was responsible for fluorescence. In turn, the chemosensor L1 acted asa selective chemosensor toward F−among various anions. Thus, L1 associated with F−with 1:1 stoi-chiometry. A recognition mechanism based on the binding modes of Hg2+and F−ions were proved bythe analytical techniques like UV–vis, changes in fluorescence,1H NMR, FT-IR, ESI-mass and HRMS. Inaddition, this chemosensor exhibited highly selective and sensitive recognition of azide (N3−) anionsupon the addition of Hg2+with a color change back to colorless in the same solution.
Tetrahedron, 2000
The selective de-tert-butylation of p-tert-butyl thiacalix[4]arene (p-tert-butyl TCA) with AlCl3 at 80°C has been investigated. Mono-, di-, and tri-p-tert-butyl thiacalix[4]arene (mono-, di- and tri-TCA, respectively) were obtained in yields of 6.5, 20 and 21%, respectively, when p-tert-butyl TCA was treated with 7.1 equiv. of AlCl3 for 30 min. De-tert-butyl TCA (TCA) was exclusively obtained when 10.5 equiv. of AlCl3 was used. These derivatives are converted to fluorescent active derivatives by modification with dansyl moiety at the lower rim, which are used as metal sensors in aqueous solution. The extent of the fluorescent variations with the metal cations was used to display the sensing factors, ΔI/I0. These hosts show much higher sensitivity for transition metal cations such as Co2+, Ni2+, and Cd2+ than those of alkali metal cations such as Li+, Na+, and K+. The effect of p-tert-butyl groups on metal sensing ability of these hosts was studied. It was found that p-tert-butyl groups decrease the sensing ability of these hosts. It is the first example to show that water soluble TCA derivatives can detect metal cations directly in aqueous solution by variation of fluorescence intensity upon addition of a metal cation.
Thiourea and its derivatives display several electronic and structural features which enable its application in various fields, ranging from biological to non-biological. These compounds contain heteroatom's like sulfur and nitrogen, which are nucleophilic and allow for establishing inter-and intramolecular hydrogen bonding. In addition, they also provide coordination sites to act as ligands in the field of coordination chemistry. Due to these properties, thiourea derivatives are used as chemosensors to detect various metal cations. This article covers a broad range of thiourea based chemosensors that are used for colorimetric and fluorimetric (turn-off and turn-on) detection of different cations such as
Journal of Luminescence, 2019
A new 2-hydroxynaphthalen based Schiff base colorimetric and fluorescence chemosensor, H 2 L {(E)-4-((2-hydroxynaphthalen-1-yl)methyleneamino)benzoic acid}, for selective sensing of Al 3+ ions has been synthesized and characterize by different physico-chemical and spectroscopic techniques. The probe shows enhanced fluorescence and significant color change from bright yellow to colorless in the presence of Al 3+ ions in methanol-water (9:1 v/v) solution, without interference from other metal ions. The binding mode of H 2 L with Al 3+ was studied by UV-vis, fluorescence titration, job's plot analysis, and ESI-MS. The probe acts as a bidentate ligand and interacts with Al 3+ ions with a binding constant of K b = 1.546 × 10 5 M-1. The limit of detection for Al 3+ is found to be 6.4 × 10 −7 M. The cytotoxicity of the probe has been evaluated by MTT assay on MCF-7 cell line, indicating more than 92% cell viability in the concentration range of 1.25-50 μM with no serious cytotoxicity on cells. Live cell imaging study clearly indicates that the 2 accumulation of Al 3+ in living cells can be detected by H 2 L.
Chemosensors
In this paper, a Schiff base ligand 1-(2-thiophenylimino)-4-(N-dimethyl)benzene (SL1) bearing azomethine (>C=N-) and thiol (-SH) moieties capable of coordinating to metals and forming colored metal complexes was synthesized and examined as a colorimetric chemosensor. The sensing ability toward the metal ions of Cu2+, Cr3+, Fe2+ Ni2+, Co2+, Mg2+, Zn2+, Fe2+, Fe3+, NH4VO3 (V5+), Mn2+, Hg2+, Pb2+, and Al3+ was investigated in a mixture of H2O and dimethylformamide (DMF) solvent using the UV–Visible spectra monitoring method. The synthesized Schiff base ligand showed colorimetric properties with Cr3+, Fe2+, Fe3+, and Hg2+ ions, resulting in a different color change for each metal that could be identified easily with the naked eye. The UV–Vis spectra indicated a significant red shift (~69–288 nm) from the origin after the addition of the ligand to these metal ions, which may be due to ligand-to-metal charge-transfer (LMCT). On applying Job’s plot, it was indicated that the ligand bind...