Спектрально-люминесцентные свойства стекол системы (Y-=SUB=-1-x-=/SUB=-Yb-=SUB=-x-=/SUB=-)-=SUB=-2-=/SUB=-О-=SUB=-3-=/SUB=--Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=--В-=SUB=-2-=/SUB=-О-=SUB=-3-=/SUB=--SiO-=SUB=-2-=/SUB=- + Cr-=SUB=-2-=/SUB=-О-=SUB=-3-=/SUB=-+Na-=SUB=-2-=/SUB=-О

Fused yttrium-alumoborate glasses doped with ytterbium, silicon, chromium, and sodium were synthesized. The influence of the matrix on the "spectroscopic behavior" of chromium ions and the efficiency of their sensitization of Yb3+ luminescence was established by spectral-luminescence and EPR-studies. It was found that (1) chromium in alkali-free glasses is mainly in the oxidation degree Cr(III) with an appreciable admixture of Cr(IV) and Cr(V), (2) the partial replacement of Al2O3 or B2O3 by SiO2 and Y2O3 by Yb2O3 affects to a different extent the relative concentration of optical centers of chromium ions, (3) the addition of alkali results in the formation of Cr(VI) centers as a result of oxidation of less charged chromium ions and predominantly tetracoordinated Cr4+ and Cr5+, (4) Cr3+ ions make the main contribution to the luminescence sensitization of Yb3+ ions, while Cr4+ ions and to a lesser extent Cr5+ play the role of luminescence quencher and internal filter. Sensitization of Yb3+ luminescence through the charge transfer band in Cr(VI) was found. An alkaline glass doped with Cr and Yb upon excitation through the sensitizer produced a luminescence quantum yield of 32% and the conditions for its enhancement were considered. It is shown that the temperature quenching of luminescence of CrYb-containing glasses is significantly lower than that of Cr-containing glasses.

Multi Metal Ion Recognizing Unsymmetrical tetra Dentate Schiff bases associated with Antifungal Activity

New unsymmetrical Schiff bases containing azomethine moiety with simple aromatic section in one side and ferrocene fragment attached imine on the other side have beensynthesized. Advent of metal-to-ligand charge transfer band for the coordination of Cu2+ ions with receptors and appropriate changes in UV-Visible spectra for other metal ion combination with the sensor is reported. Observed extravagant ΔEpvalues suggest quasi-reversible process. The ΔIpa amount calculated from the anodic current Ipa value noticed for receptor solution and different metal ion added sensor solution discloses the concentration of metal ions required for effective sensing. The synthesized ligands were subjected to antimicrobial activity against four bacterial and two fungal stains and the zone of inhibition (in mm) was calculated. Further molecular docking study was carried out and the binding energy (Kcal.mol-1) for the synthesized ligand (R1 and R2) with the selected protein was intended.

Momentum-resolved visualization of electronic evolution in doping a Mott insulator

High temperature superconductivity in cuprates arises from doping a parent Mott insulator by electrons or holes. A central issue is how the Mott gap evolves and the low-energy states emerge with doping. Here we report angle-resolved photoemission spectroscopy measurements on a cuprate parent compound by sequential in situ electron doping. The chemical potential jumps to the bottom of the upper Hubbard band upon a slight electron doping, making it possible to directly visualize the charge transfer band and the full Mott gap region. With increasing doping, the Mott gap rapidly collapses due to the spectral weight transfer from the charge transfer band to the gapped region and the induced low-energy states emerge in a wide energy range inside the Mott gap. These results provide key information on the electronic evolution in doping a Mott insulator and establish a basis for developing microscopic theories for cuprate superconductivity.