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A simple and effective fluorescence “turn on” chemosensor (ZPA) has been synthesized for rapid, sensitive and selective detection of copper ions (Cu 2+ ) in fully aqueous buffer. The binding interaction between ZPA and Cu 2+ was investigated through UV–vis absorption, fluorescence measurement, mass spectroscopy, and IR spectrum analysis. Cu 2+ could specifically bind with the hydroxyl-O and imine-N atom in ZPA with high affinity ( K a  = 6.08 × 10 7  M −1 ). Coordination of Cu 2+ to ZPA restricting the photoinduced electron transfer (PET) process in free ZPA and generating a more rigid ZPA/Cu 2+ complex with an extended π-electron conjugation system, sequentially leading to the fluorescence enhancement of ZPA. The detection limit (calculated to be 1.49 × 10 −8  M) was far below the limit in the World Health Organization (WHO) guidelines for drinking water (30 μM) and the sensing process was fully reversible. Practical applications of ZPA for Cu 2+ detection in real water samples were investigated with satisfactory results. Endowed with attributes like high binding affinity, specificity, relatively long excitation/emission properties and excellent bio-compatibility, ZPA demonstrated outstanding fluorescent imaging of intracellular Cu 2+ in living cells. [ABSTRACT FROM AUTHOR]

A zinc(II) porphyrin derivative (ZPSN) was designed and synthesized, and this probe exhibited rapid, selective and reversible binding to Cu + for fluorescence monitoring in pure aqueous buffer. The detection mechanism is based on Cu + -activated disruption of axial coordination between the pyridyl ligand and the zinc center, which changes the molecular geometry and inhibits intramolecular electron transfer (ET), leading to fluorescence enhancement of the probe. The proposed sensing mechanism was supported by UV-vis spectroscopy/fluorescence spectral titration, NMR spectroscopy, mass spectrometry, and time-resolved fluorescence decay studies. The dissociation constant was calculated to be 6.53 × 10 -11 M. CLSM analysis strongly suggested that ZPSN could penetrate live cells and successfully visualize Cu + in mitochondria. This strategy may establish a design and offer a potential building block for construction of other metal sensors based on a similar mechanism.

The title compound, C(14)H(15)BrN(2)O(2), an inter-mediate in drug discovery, was synthesized by the reaction of 5-bromo-pyridin-2-amine and 3,4-dimeth-oxy-benzaldehyde. In the crystal, molecules are linked via pairs ofN-H⋯N hydrogen bonds, leading to the formation of inversion dimers. A short contact occurs between the aryl H atom (ortho position from N) and the centroid of the benzene ring.