On the incorporation of iron into hexagonal barium titanate: I. electron paramagnetic resonance (EPR) study

A New Coumarin-Acridone Compound as a Fluorescence Probe for Fe3+ and Its Application in Living Cells and Zebrafish

A new coumarin-acridone fluorescent probe S was designed and synthesized, and the structure was confirmed with ¹H/¹³C NMR spectrometry, single-crystal X-ray diffraction, and high-resolution mass spectrometry. This probe has high sensitivity and selectivity for Fe³⁺ over other testing metal ions at 420 or 436 nm in acetonitrile-MOPS (3-Morpholinopropanesulfonic Acid) buffer solution (20.0 μM, pH = 6.9, 8:2 (v/v)). Under physiological conditions, the probe displayed satisfying time stability with a detection limit of 1.77 µM. In addition, probe S was successfully used to detect intracellular iron changes through a fluorescence-off mode, and the imaging results of cells and zebrafish confirmed their low cytotoxicity and satisfactory cell membrane permeability, as well as their potential biological applications.

On the incorporation of iron into hexagonal barium titanate: II. Magnetic moment, electron paramagnetic resonance (EPR) and optical transmission

Systematic measurements of the magnetic moment in dependence on temperature and magnetic field of hexagonal 6H-BaTiO3 + 0.04 BaO + x/2 Fe2O3 (0.005 ⩽ x ⩽ 0.05) ceramics were performed to study the influence of Fe ions on the magnetic properties. While the samples show Curie-Weiss paramagnetism for Fe concentrations ⩽1.0 mol%, antiferromagnetic interactions become manifest for 2.0 and 5.0 mol% iron. With increasing Fe content the antiferromagnetic interaction, which is assumed to be caused by a superexchange mechanism [Formula: see text], becomes stronger. At external magnetic fields smaller than 1 T a further, ferromagnetic interaction between Fe3+ ions is detected below 200 K. The interactions between Fe3+ ions in the samples with 2.0 and 5.0 mol% iron are also manifest in the EPR spectra by numerous lines with low intensity. Q-band EPR investigations of 5.0 mol% Fe doped single crystals confirm the existence of only one type of Fe3+-VO associates in the samples.