Magneto-metric Hamiltonians on quantum surfaces in the configuration space

The paper deals with the Schrödinger operator on a generic Riemann surface in a generic magnetic field. On a class of nano-momentum states, this operator is reduced to a system with one degree of freedom whose (quantized) phase space is the given configuration surface. The Hamiltonian of the reduced system is a joint geometric invariant of metric and magnetic tensors. Its spectrum can be computed semiclassically, which provides the asymptotics of eigenvalue clusters for the original Schrödinger operator near the ground level.     

Photochemical properties of mixed-ligand complexes europium carboxylates

The photochemical behavior of mixed-ligand complexes of europium carboxylates with nitrogen-and phosphorus-containing neutral ligands of island and dimer types, Eu(L)₃ · xD · nH₂O and [Eu(L)₃ · xD]₂ · nH₂O (L is the trifluoroacetate, toluate, or cinnamate anion), was studied. During UV irradiation of the complexes of europium carboxylates with 1,10-phenanthroline and 2,2′-dipyridyl, a luminescence buildup was observed. EPR measurements demonstrated that the observed buildup of luminescence from europium occurs in parallel with the increase of the concentration of radical anions formed from neutral ligands.     

Structure and luminescence properties of tellurium(IV) complex compounds

Using the tellurium(IV) complex compounds as an example, we study the interrelation between the geometric structure and spectral luminescence properties. We find that, in the series of compounds of Te(IV), which are characterized by the island octahedral coordination of Te(IV) ions, the luminescence intensity depends on the degree of distortion of the Te(IV) coordination polyhedron, the Stokes shift, and the energy of the luminescence transition. We revealed that the considered series of Te(IV) compounds possess reversible thermochromic properties.     

Intramolecular charge transfer and electronic absorption and luminescence spectra of fluoroquinolinones

TD-DFT study on the effect of donor and acceptor substituents on molecular orbital localization and charge distribution in fluoroquinolinone molecules showed that their photoexcitation is accompanied by electron density redistribution over particular fragments. Depending on the protolytic form, frontier molecular orbitals are localized on different fragments, whereas variation of substituents weakly affects localization of these orbitals.     

NMR and luminescence spectroscopy study of the formation of mixed europium β-diketonate complexes with trifluoroacetic acid in nonaqueous solutions

The ligand substitution in Eu(AA)₃ · Phen-CDCl₃-TFA systems, where AA is acetylacetone, Phen is 1,10-phenanthroline, and TFA is trifluoroacetic acid was studied at various molar ratios (m) of competing ligands (m = TFA/AA) using NMR (¹H, ¹⁹F) and luminescence spectroscopy. The formation of mixed Eu(AA)₂(TFA) · Phen and Eu(AA)(TFA)₂ · Phen complexes in the resultant solutions was attested. The luminescence spectra were studied. The competitive capacity of TFA was ascertained to be higher than that of AA. Depending on the m value, the substitution of acido ligands was shown to occur successively according equations Eu(AA)₃ · Phen + (TFA) _n = Eu(AA)_{3 − n} (TFA) _n · Phen + (AA) _n (n = 1, 2, 3).     

New luminophor-activators based on (fluoro)quinolone antibacterials

It was shown that (fluoro)quinolone antibiotics form strongly fluorescent solid-state complexes with Eu(III) and Tb(III) lanthanide ions, with a wavelength red-shift beneficial for applications to greenhouse-cover polymers. Complexes with optimal properties were prepared by the mechanical activation of fine-dispersed composite mixtures with the lanthanide salts. The spectral properties, photo-stability to UV-light, and compatibility with the polyethylene matrix were investigated. The formulation additives of the tablet forms of the antibiotic medicines did not quench the fluorescence from the lanthanide ions. Therefore, the outdated drug forms of the antibiotics can serve as cheap recyclable sources for the covering material of greenhouses. In addition, diphenylguanidine (DPG) was investigated as a coligand. DPG enhanced fluorescence of the fluoroquinolone complexes by decreasing the non-radiative energy loss through O-H vibration of H₂O.