Kuoxi Xu

Acridine-based enantioselective fluorescent sensors for the malate anion in water

Compounds S-1, S-2, S-3 and R-1 were synthesized and the interactions of all of the compounds with the malate anion were studied in H2O (comprising 0.3% DMSO and 0.01 M HEPES at pH = 7.4) by fluorescence titration experiments. Sensor S-1 was found to present good enantioselective fluorescent sensing ability towards the malate anion. The results indicated that sensor S-1 was very promising as a fluorescent sensor for recognition of the malate anion in H2O solution.

Acridine-based complex as amino acid anion fluorescent sensor in aqueous solution.

Novel acridine-based fluorescence sensors containing alaninol ligands, L1 and D1, were designed and synthesized. The structure of the compound was characterized by IR, (1)H NMR, (13)C NMR, MS spectra. L1 and D1 possess efficient Cu(2+) cation ON-OFF selective signaling behavior based on ligand-to-metal binding mechanism at physiological pH condition. Additionally, the L1-Cu(II) and D1-Cu(II) complexes could further serve as reversible OFF-ON signaling sensing ensemble to allow ratiometric response to amino acid anion in aqueous solution.

Study on the synthesis of novel fluorescent macrocyclic sensors and their sensitive properties for Cu2+ and Fe3+ in aqueous solution

Abstract In this work, we synthesised and characterised three novel fluorescence macrocyclic sensors containing optically active dansyl groups. The studies for the interaction of the synthesised compounds with various mental ions (Li+, Na+, K+, Ag+, Mg2+, Ca2+, Ba2+, Pb2+, Zn2+, Co2+, Cd2+, Hg2+, Ni2+, Cu2+, Mn2+, Cr3+, Al3+, Fe3+) were performed by fluorescence titration, Job’s plot, ESI-MS and DFT calculations. The results showed that the sensors 1a–1c displayed selective recognition for Cu2+ and Fe3+ ions and formed stoichiometry 1:1 complex through PET mechanism in DMSO/H2O solution (1:1, v/v, pH 7.4 of HEPES). The binding constant (K) and detection limit were calculated. We reported the synthesis of three novel fluorescence macrocyclic sensors containing optically active dansyl groups. The studies for the interaction of the synthesized compounds with various mental ions (Li+, Na+, K+, Ag+, Mg2+, Ca2+, Ba2+, Pb2+, Zn2+, Co2+, Cd2+, Hg2+, Ni2+, Cu2+, Mn2+, Cr3+, Al3+, Fe3+) were performed by fluorescence titration, Job’s plot, ESI-MS and DFT calculations. The results showed that the sensors 1a–1c displayed selective recognition for Cu2+ and Fe3+ ions and formed stoichiometry 1:1 complex through PET mechanism in DMSO/H2O solution (1:1, v/v, pH 7.4 of HEPES). The binding constant (K) and detection limit were calculated.

Novel naphthalene-based fluorescent chemosensors for Cu2+ and Fe3+ in aqueous media

Three novel compounds bearing 2,7-dihydroxylnaphthalene capable of detecting Cu2+ or Fe3+ have been synthesised based on photoinduced electron transfer. The ability of these compounds for complex transition metal ions has been studied, and complex stoichiometry for Cu2+ and Fe3+ complex has been determined in the Tris–HCl (0.01 M DMSO/H2O (v/v) 1:1, buffer, pH 7.4) solution system by fluorescence titration experiments. These chemosensors form a 1:1 complex with Cu2+ or Fe3+ and show a fluorescent quenching with a binding constant of (4.46 ± 0.29) × 103 and (8.04 ± 0.26) × 104, respectively.

A quinoline-based Cu2 + ion complex fluorescence probe for selective detection of inorganic phosphate anion in aqueous solution and its application to living cells

A quinaldine functionalized probe QP has been designed and synthesized. It exhibited selective turn-off fluorescence response toward Cu2+ ion over most of the biologically important ions at physiological pH. The binding ratio of the probe QP and Cu2+ ion was determined to be 1:1 through fluorescence titration, Jobs plot and ESI-MS. The binding constant (K) of Cu2+ to probe QP was found to be 2.12×104M-1. Further, the Cu2+ ensemble of probe QP was found to respond H2PO4- and HPO42- among other important biological anions via fluorescence turn-on response at physiological pH. Fluorescence microscopy imaging using living Hela cells showed that probe QP could be used as an effective fluorescent probe for detecting Cu2+ cation and H2PO4- and HPO42- anions in living cells.

A pair of chiral fluorescent sensors for enantioselective recognition of mandelate in water.

A pair of chiral compounds S-1 and R-1 derived from (1S, 2S) or (1R, 2R)-1, 2-diphenylethane-1, 2-diamine were designed and synthesized, the interactions of S-1 and R-1 with mandelate were studied in H2O (0.01 M HEPES buffer, pH=7.4) by fluorescence titration experiments. The sensors S-1 and R-1 were found to present enantioselective fluorescent sensing ability to mandelate. The results indicated that the sensors S-1 and R-1 were very promising to be used as fluorescent sensors in determining the enantiomeric composition of mandelate in H2O.

A novel turn-on fluorescent probe for Al3 + and Fe3 + in aqueous solution and its imaging in living cells

A quinoline-based fluorescence probe has been prepared and characterized. Probe 1 showed a selective sensing ability for Al3+ and Fe3+ ions through fluorescence enhancement response at 515nm when it was excited at 360nm. In the presence of Fe3+ ion, probe 1 exhibited a detection limit of 2.10×10-6M. As for Al3+, its detection limit of 3.58×10-7M was significantly lower than the highest limit of Al3+ in drinking water recommended by the WHO (7.41μM), representing a rare example in reported fluorescent probe for Al3+ ion. The fluorescence microscopy experiments have demonstrated that probe 1 could be used in live cells for the detection of Al3+ and Fe3+ ions.

Novel enantioselective fluorescent sensors for tartrate anion based on acridinezswsxa

Novel chiral fluorescence sensors L-1 and D-1 incorporating N-Boc-protected alanine and acridine moieties were synthesized. The recognition ability of the sensors was studied by fluorescence titration, 1 H NMR spectroscopy and density functional theory (DFT) calculations. The sensors exhibited good enantioselective fluorescent sensing ability toward enantiomers of tartrate anion for the selected carboxylate anions and formed 1: 1 complexes by multiple hydrogen bonding interactions.

Acridine-based fluorescence chemosensors for selective sensing of Fe 3+ and Ni 2+ ions

Two novel acridine-based fluorescence chemosensors (L1 and L2) were prepared and their metal ions sensing properties were investigated. L1 (L2) exhibited an excellent selective fluorescence response toward Fe3+ (Ni2+) and the stoichiometry ratio of L1-Fe3+ and L2-Ni2+ were 1:1. The detection limits of L1 and L2 were calculated by the fluorescence titration to be 4.13μM and 1.52μM, respectively, which were below the maximum permissive level of Fe3+ and Ni2+ ions in drinking water set by the EPA. The possible mechanism of the fluorescence detection of Fe3+ and Ni2+ had been proposed according to the analysis of Jobs plot, IR spectra and ESI-MS. The determination of Fe3+ and Ni2+ ions in living cells had been applied successfully.

Novel fluorescent chemosensors based on tryptophan unit for Cu2+ and Fe3+ in aqueous solution

We reported four fluorescent chemosensors containing tryptophan units. The fluorescence spectrum titration experiments suggest that chemosensors 1, 2, 3 and 4 are highly selective for Cu2+ and Fe3+ over Li+, Na+, K+, Co2+, Zn2+, Ni2+, Hg2+ and Cr3+via forming complexes with Cu2+ or Fe3+, which is confirmed by dramatical quench of fluoreseence in aqueous solution at pH 7.4, thus making all the chemosensors suitable for Cu2+ and Fe3+ fluorescent sensors.