Synthesis, characterization and selective fluorescent zinc(II) sensing property of three Schiff-base compounds

A novel chromone Schiff base as Zn2+ turn-on fluorescent chemosensor in a mixed solution

In this study, a novel fluorescent chemosensor 1 based on chromone-3-carboxaldehyde Schiff base was synthesized and featured through nuclear magnetic resonance (NMR) and mass spectra. Spectroscopic investigation indicated that the fluorescent sensor showed high selectivity toward Zn2+ over other metal ions and that the detection limit of 1 could reach 10-7  M. These indicated that 1 acted as a highly selective and sensitive fluorescence chemosensor for Zn2+ .

A new diformyl phenol based chemosensor selectively detects Zn2+ and Co2+ in the nanomolar range in 100% aqueous medium and HCT live cells

A new diformyl phenol based chemosensor that can sense Zn2+ and Co2+ in the nanomolar range in 100% aqueous solution and in HCT cells was explored.

A Fluorescent Chemosensor Based on Schiff Base for the Determination of Zn2+, Cd2+and Hg2

Metal complexes were obtained by the reaction of zinc, cadmium and mercury(II) salts with Schiff base HL (N(salicylidene)benzylamine). HL was synthesized by the condensation reaction of benzylamine and 2-hydroxybenzaldehyde. The fluorescence properties of the Schiff base and its metal complexes were studied in ethanol-water solutions. HL was examined for its utility as a fuorescent chemosensor for the determination of Zn²⁺, Cd²⁺ and Hg²⁺ in aqueous samples. The HL chemosensor was found to be sensitive to Zn²⁺, Cd²⁺ and Hg²⁺ than some metal ions and its complexes emitted strong fluorescence at 452 nm for Zn²⁺ at 474 nm for Cd²⁺ and at 491 nm for Hg²⁺, respectively. It was determined that HL forms complexes with a ratio of 2:1 for Zn²⁺ and Hg²⁺ and with a ratio of 1:1 for Cd²⁺ by Job plots. For the detection of Zn²⁺, Cd²⁺ and Hg²⁺ in aqueous samples, pH, solvent type and ligand concentration were optimized for an analytical method based on HL chemosensor. HL gave a wide range of linearity with Zn²⁺, Hg²⁺ and Cd²⁺, the limit of detection was found to be 2.7 × 10^-7 M, 7.5 × 10^-7 M and 6.0 × 10^-7 M, respectively.

Zinc complexes as fluorescent chemosensors for nucleic acids: new perspectives for a "boring" element

Zinc(II) complexes are effective and selective nucleic acid-binders and strongly fluorescent molecules in the low energy range, from the visible to the near infrared. These two properties have often been exploited to quantitatively detect nucleic acids in biological samples, in both in vitro and in vivo models. In particular, the fluorescent emission of several zinc(II) complexes is drastically enhanced or quenched by the binding to nucleic acids and/or upon visible light exposure, in a different fashion in bulk solution and when bound to DNA. The twofold objective of this perspective is (1) to review recent utilisations of zinc(II) complexes as selective fluorescent probes for nucleic acids and (2) to highlight their novel potential applications as diagnostic tools based on their photophysical properties.

Synthesis and Fe3+ Recognition of Novel Triazole Schiff-Base Derivatives Bearing Fluorogenic Naphthalene and Anthracene Units

Novel triazole Schiff-bases derivatives have been synthesised from 3,5-diaryl-4-amino-1,2,4-triazole with naphthaldehyde and anthraldehyde. The emission spectrum of 3,5-diphenyl-4-(anthrylmethyleneamino)-1,2,4-triazole exhibited fluorescent quenching upon chelation to Fe3+ ions.

A highly selective chemosensor for Al3+ based on 2-oxo-quinoline-3-carbaldehyde Schiff-base

A new Schiff-base ligand (1) with good fluorescence response to Al(3+), derived from 2-oxo-quinoline-3-carbaldehyde and nicotinic hydrazide, had been synthesized and investigated in this paper. Spectroscopic investigation revealed that the compound 1 exhibited a high selectivity and sensitivity toward Al(III) ions over other commonly coexisting metal ions in ethanol, and the detection limit of Al(3+) ions is at the parts per billion level. The mass spectra and Job's plot confirmed the 1:1 stoichiometry between 1 and Al(3+). Potential utilization of 1 as intracellular sensors of Al(3+) ions in human cancer (HeLa) cells was also examined by confocal fluorescence microscopy.

Bis(2-{[(9H-fluoren-2-yl)methyl-idene]amino}-phenolato-κ(2)N,O)zinc methanol disolvate

In the title compound, [Zn(C(20)H(14)NO)(2)]·2CH(3)OH, the Zn(II) atom lies on a crystallographic twofold rotation axis and is coordinated by two O atoms and two N atoms from two bidentate 2-{[(9H-fluoren-2-yl)methyl-idene]amino}-phenolate ligands within a distorted tetra-hedral geometry. The dihedral angle between the two chelate rings is 82.92 (5)°. In the coordinated ligand, the phenol ring is twisted at 30.22 (9)° from the mean plane of the fluorene ring. In the crystal, O-H⋯O hydrogen bonds link the complex mol-ecules to the methanol solvent mol-ecules.

Fluorescence "turn-on" chemosensor for the selective detection of zinc ion based on Schiff-base derivative

N,N'-phenylenebis(salicylideaminato) (L) has been used to detect trace amounts of zinc ion in acetonitrile-water solution by fluorescence spectroscopy. The fluorescent probe undergoes fluorescent emission intensity enhancement upon binding to zinc ions in MeCN/H(2)O (1:1, v/v) solution. The fluorescence enhancement of L is attributed to the 1:1 complex formation between L and Zn(II), which has been utilized as the basis for selective detection of Zn(II). The linear response range for Zn(II) covers a concentration range of 1.6x10(-7) to 1.0x10(-5)mol/L, and the detection limit is 1.5x10(-7)mol/L. The fluorescent probe exhibits high selectivity over other common metal ions, and the proposed fluorescent sensor was applied to determine zinc in water samples and waste water.