Electronic Structure and Magnetism in Transition Metals Doped 8-Hydroxy-Quinoline Aluminum

Preparation and Characterization of Paramagnetic Bis (8-Hydroxyquinoline) Manganese Crystals

The magnetic properties of π-conjugated bis (8-hydroxyquinoline) manganese (Mnq₂) crystals are investigated. Rod-shaped Mnq₂ crystals are prepared by using the physical vapor deposition method. Field emission scanning electronic microscopy spectra show that the Mnq₂ nanorods have perfect plane quadrangular ends. Energy dispersive spectrometer and X-ray photoelectron spectroscopy analysis demonstrates that the powders and nanorods are the same compound with a high purity. X-ray diffraction analysis shows the high crystal quality of the prepared Mnq₂ nanorods. The magnetic measurement, using alternating gradient magnetometer and magnetic property measurement system superconducting quantum interference device vibrating sample magnetometer, indicates that the prepared Mnq₂ nanorods show a paramagnetic property at room temperature. First-principles density functional theory (DFT) calculations are used to study the electronic structure and magnetic properties of the prepared Mnq₂ crystals. DFT calculations show that the magnetic moment of the Mnq₂ isolated molecule is 5 μ_B, which mainly comes from the localized Mn 3d orbital. The energy difference between the antiferromagnetic and ferromagnetic states of the Mnq₂ monoclinic cell is only 0.1 meV, which may explain the paramagnetic property observed in the prepared Mnq₂ nanorods and also indicates the difficulty of preparing intrinsic ferromagnetic Mnq₂ crystals.

A curious interplay in the films of N-heterocyclic carbene Pt(II) complexes upon deposition of alkali metals

The recently synthesized series of Pt^II complexes containing cyclometallating (phenylpyridine or benzoquinoline) and N-heterocyclic carbene ligands possess intriguing structures, topologies, and light emitting properties. Here, we report curious physicochemical interactions between in situ PVD-grown films of a typical representative of the aforementioned Pt^II complex compounds and Li, Na, K and Cs atoms. Based on a combination of detailed core-level photoelectron spectroscopy and quantum-chemical calculations at the density functional theory level, we found that the deposition of alkali atoms onto the molecular film leads to unusual redistribution of electron density: essential modification of nitrogen sites, reduction of the coordination Pt^II centre to Pt⁰ and decrease of electron density on the bromine atoms. A possible explanation for this is formation of a supramolecular system “Pt complex-alkali metal ion”; the latter is supported by restoration of the system to the initial state upon subsequent oxygen treatment. The discovered properties highlight a considerable potential of the Pt^II complexes for a variety of biomedical, sensing, chemical, and electronic applications.

Room temperature ferromagnetic properties of dysprosium-doped tris(8-hydroxyquinoline) aluminum: experimental and theoretical investigation

Room-temperature ferromagnetism was observed in a Dy-doped Alq₃ film.

Structure of Co-Doped Alq3 thin films investigated by grazing incidence X-ray absorption fine structure and Fourier transform infrared spectroscopy

The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.