•The novel fluorescent sensors based on acridine can selective recognize Cu2 + through ligand-to-metal binding process.•The reported fluorescent sensors for the selective recognition of amino acid anion using metal complex in aqueous solutions•The binding constants were calculated.Novel acridine-based fluorescence sensors containing alaninol ligands, L1 and D1, were designed and synthesized. The structure of the compound was characterized by IR, 1H NMR, 13C NMR, MS spectra. L1 and D1 possess efficient Cu2 + 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.A pair of new acridine fluoroionophore containing two alaninol ligands, L1 and D1, was designed and synthesized. The structures of these compounds were characterized by IR, MS, 1H NMR, 13C NMR spectra and elemental analysis. Their photophysical properties toward metal ions were studied by absorption and fluorescence spectra. The presence of Cu2 + resulted in significant quenching of the fluorescence emission from sensor, while other metal ions posed little interferences. The fluorescence response was concentration-dependent and induced the formation of a 1:1 ligand/metal complex in buffered aqueous. Additionally, the Cu2 + complex ensemble could further serve as a probe to act as a sensor for amino acid anion via a complex mode.

•The novel fluorescent sensors based on acridine can enantioselective recognize malate anion.•In the binding with malate anion, the large fluorescence increase can be attributed to the PET mechanism.•The binding constants were calculated and binding mechanism was given.The compounds L-1 and L-2 were synthesized and the interactions of all of the compounds with malate anion were studied by fluorescent titration and 1H NMR experiments. The Sensors L-1 and L-2 were found to present good enantioselective fluorescent sensing ability to malate anion. The results indicated that sensors L-1 and L-2 were very promising to be used as fluorescent sensors in determining malate anion in CH3CN.The compounds L-1 and L-2 were synthesized and the interactions of all of the compounds with malate anion were studied in CH3CN by fluorescent titration and H NMR experiments. The Sensors L-1 and L-2 were found to present good enantioselective fluorescent sensing ability to malate anion. The results indicated that sensors L-1 and L-2 were very promising to be used as fluorescent sensors in determining malate anion in CH3CN.

•In binding with Cu2+ and Fe3+, the large fluorescence decrease can be attributed to the PET mechanism.•The chemosensors exhibited the highest sensitivity for Cu2+ or Fe3+ in Tris–HCl (0.01 M DMSO/H2O (v/v) 1:1, buffer, pH=7.4) solution system.•The binding constants were calculated.We have developed carbazole-based fluorescent chemosensors that exhibit fluorescence quenching upon binding Cu2+ and Fe3+ in the Tris–HCl (0.01 M DMSO/H2O (v/v) 1:1, buffer, pH=7.4) solution system by fluorescence titration experiments at 25 °C. These sensors form a 1:1 complex with Cu2+ or Fe3+ and show a fluorescent quenching based on photoinduced electron transfer (PET) with a binding constant of (3.44±0.05)×103 and (1.50±0.06)×104, respectively. All the chemosensors (1–4) show the highest sensitivity for Cu2+ and Fe3+ over other metal cations 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.

Sequential fluorescence sensing of Zn2+/Cd2+ ions and phosphate anion by new quinoline based sensors(L1 and L2) have been presented. Sensors exhibit highly selective fluorescence “turn-on” sensing properties to Zn2+/Cd2+ ions in CH3OH/H2O(1/1, v/v, Tris, 10 mol·L−1, pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H2PO4- and HPO42- anions through fluorescence “turn-off” respond. The results of Zn2+/Cd2+ ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn2+/ Cd2+ ions and phosphate anion detection in aqueous media.Sequential fluorescence sensing of Zn2+/Cd2+ ions and phosphate anion by new quinoline based sensors (L1 and L2) have been presented. Sensors exhibit highly selective and sensitive fluorescence “turn-on” sensing properties to Zn2+/Cd2+ ions in CH3OH/H2O(1/1, v/v, Tris, 10 mM, pH 7.4) solution with a 1:1 binding stoichiometry. The complexes display high selectivity to H2PO4- and HPO42- anions through fluorescence “turn-off” respond. Zn2+/Cd2+ ions and phosphate anion sequential recognition via fluorescence changes make sensors L1 and L2 have potential utility for Zn2+/ Cd2+ ions and phosphate anion detection in aqueous media.