Процессы передачи энергии в эвлитите Sr-=SUB=-3-=/SUB=-Y(PO-=SUB=-4-=/SUB=-)-=SUB=-3-=/SUB=-, по отдельности и одновременно легированном ионами Tb-=SUP=-3+-=/SUP=- и Tm-=SUP=-3+-=/SUP=-

In this work the optical spectroscopy and the energy transfer processes involving the Tb3+and Tm3+ ions, have been studied in eulytite double phosphate hosts of the type Sr3Y(PO4)3 doped with various amounts of the two Ln ions. It has been found that several energy transfer and cross-relaxation processes are active in this class of materials, upon excitation in the 5D4 level of Tb, and in the 1G4 one of Tm. In particular, a Tb→Tm transfer of excitation has been found to quench strongly the 5D4 level of Tb. This process occurs with a transfer efficiency increasing from 0.08 to 0.62, for a donor concentration of 2 mol%, and an acceptor concentration increasing from 2 to 15 mol%. The emission spectra are strongly affected by the presence of Tb⟷Tm energy transfer, and Tm→Tm cross relaxation processes.

Dinuclear cobalt(II) complexes with double phosphate ester bridges and tetradentate ligands having anisole or quinoline appendages

Phosphate esters provide a rigid and stable polymeric backbone in nucleic acids. Metal complexes with phosphate ester groups have been synthesized as structural and spectroscopic models of phosphate-containing enzymes. Dinucleating ligands are used extensively to synthesize model complexes since they provide the support required to stabilize such complexes. The crystal structures of two dinuclear CoII complexes, namely bis(μ-diphenyl phosphato-κ2 O:O′)bis({2-methoxy-N,N-bis[(pyridin-2-yl)methyl]aniline-κ4 N,N′,N′′,O}cobalt(II)) bis(perchlorate), [Co(C12H10O4P)2(C19H19N3O)2](ClO4)2, and bis(μ-diphenyl phosphato-κ2 O:O′)bis({N,N-bis[(pyridin-2-yl)methyl]quinolin-8-amine-κ4 N,N′,N′′,O}cobalt(II)) bis(perchlorate), [Co(C12H10O4P)2(C21H18N4)2](ClO4)2, with tetradentate 2-methoxy-N,N-bis[(pyridin-2-yl)methyl]aniline (L 1) and N,N-bis[(pyridin-2-yl)methyl]quinolin-8-amine (L 2) ligands are reported. The complexes have similar structures, with distorted octahedral geometries around the metal centres. Both are centrosymmetric (Z′ = 0.5), with the CoII centres doubly bridged by diphenyl phosphate ester groups. A number of aromatic–aromatic interactions are present and differ between the two complexes as the anisole group in L 1 is replaced by a quinoline group in L 2. A detailed study of these interactions is presented.

Synchrotron Radiation Study of Interconfigurational 5d-4f Luminescence of Pr3+ in KLuP2O7

The double phosphate KLuP2O7 doped with Pr3+ ions was prepared by solid-state reaction. The material obtained was characterized by powder X-ray diffraction. The luminescence spectroscopy and the excited state dynamics of this material were studied upon excitation with VUV synchrotron radiation. The 5d-4 f emission of Pr3+ upon both direct and band gap excitation was detected and assigned. The decay kinetics of the Pr3+ 5d-4 f emission is characterized by a decay time of about 20 ns and is nearly temperature independent within the range 8 - 300 K. Both dynamics and energy transfer peculiarities revealed in the study suggested good potentials for application of KLuP2O7:Pr3+ as a fast scintillator material.