Crystal structure and Hirshfeld surface analysis of the anionic tetrakis-complex of lanthanum(III) NMe4LaL 4 with the CAPh-ligand dimethyl (2,2,2-trichloroacetyl)phosphoramidate

The anionic tetrakis-complex of lanthanum(III) NMe4LaL 4 with the CAPh-ligand dimethyl (2,2,2-trichloroacetyl)phosphoramidate (HL), namely, tetramethylammonium tetrakis{2,2,2-trichloro-1-[(dimethoxyphosphoryl)imino]ethanolato}lanthanum(III), (C4H12N)[La(C4H6Cl3NO4P)4], has been synthesized, crystallized and structurally characterized by X-ray diffraction. The lanthanide ion is surrounded by four anionic, bis-chelating CAPh ligands forming the complex anion with a coordination number of eight for La3+ and NMe4 + as the counter-ion. The coordination polyhedron of the La3+ ion was interpreted as a triangular dodecahedron.

4f-LUMINESCENCE OF LANTHANIDE IONS IN REGIOISOMERIC CORROLE COMPLEXES

Isomeric ditopic corroles and complexes of Yb (III), Nd (III) and Er (III) based on them were synthesized and corrole-photosensitized 4f-luminescence in near infrared region was revealed. The structure of isomeric complexes allows adjusting the distance between the corrole core and lanthanide ion. The obtained results show that the sensitization mechanism changes drastically for both different lanthanides and isomeric forms.

Mechanisms of Upconversion Luminescence of Er3+-Doped NaYF4 via 980 and 1530 nm Excitation

To date, the mechanisms of Er3+ upconversion luminescence via 980 and 1530 nm excitation have been extensively investigated; however, based on discussions, they either suffer from the lack of convincing evidence or require elaborated and time-consuming numerical simulations. In this work, the steady-state and time-resolved upconversion luminescence data of Er3+-doped NaYF4 were measured; we therefore investigated the upconversion mechanisms of Er3+ on the basis of the spectroscopic observations and the simplified rate equation modeling. This work provides a relatively simple strategy to reveal the UCL mechanisms of Er3+ upon excitation with various wavelengths, which may also be used in other lanthanide ion-doped systems.

Magnetic Properties of Novel Layered Disulfides CuCr0.99Ln0.01S2 (Ln = La…Lu)

The comprehensive study of the lanthanide-doped solid solutions CuCr0.99Ln0.01S2 (Ln = La…Lu) magnetic properties was carried out using static magnetochemistry and differential scanning calorimetry techniques. It was shown that magnetic properties of CuCr0.99Ln0.01S2 are significantly affected by the magnetic properties of the lanthanide ion. The magnetic susceptibility and the effective magnetic moment were found to deviate from the Curie-Weiss law in the temperature 90 K below and 50 K above the order-disorder transition at 695 K. The observed behavior of the temperature dependence of the effective magnetic moment in the order-disorder transition temperature region was described as a result of copper atoms redistribution over different types of the crystallographic sites.

SYNTHESIS AND SPECTRAL CHARACTERISTICS OF HETEROMETALLIC COMPLEXES OF Pr(III) WITH Zn(II), CO(II) BASED ON ETHYLENEDIAMINETETRAACETIC AND ETHYLENEDIAMINEDISUCCINIC ACIDS

New heterometallic f-d-complexes of Pr (III), Co(II), Zn(II) with aminopolycarboxylic acids (ethylenediaminetetraacetic, ethylenediaminedisuccinic acids) have been synthesized and spectroscopically characterized. It was found that complexes with a molar ratio of Pr:M3d: EDTA=1:2:2 are formed for ethylenediaminetetraacetic compounds, and that in the case of complexes based on EDDS, heteronuclear compounds of the equimolar composition Pr: M3d: EDDS = 1: 1: 1 are formed. It is shown that it is expedient to carry out the synthesis of heterometallic complexes on the basis of mono­nuclear polycarboxylates of 3d metals, which act as a «building block» for the preparation of a heterobinuclear compound by the exo coordination of additional metal ions. The complexes are characterized by the method of electron absorption spectroscopy. It is shown that independent of 3d-metal, for both heterometallic systems based on EDDS, a hypsochromic shift of the absorption maxima relative to νmax is observed for the homonuclear praseodymium complex. For ethylenediaminetetraacetate systems, the absorption maxima undergo both low- and high-frequency shift, which indicates the different nature of the ligand field effect, which is caused primarily by differences in the structure of the corresponding heteronuclearaminopolycarboxylates due to the presence of a chiral carbon atom in the EDDS molecule. For the supersensitive transitions Pr(III)) 3H4 →3P2 and 3H4 → 1D2 , the covalence parameters of the Ln-O bond have been calculated: osci­llator power (P), nepheloxetic parameter (β), covalence parameter (b1/2), Sinha parameter (δ). Analysis of the spectroscopic parameters indicates a decrease in the covalence of the lanthanide-ligand bond in the transition from mono- to heteronuclear complex, and a decrease in the local symmetry of the lanthanide ion occurs in the order Ln (III) aqua ion <hete­rometallic complex <monometallic complex. Heteronuclear complexes are several orders of magnitude more stable than mononuclear ones due to the formation of additional bonds or metallacycles with donor ligand atoms. It is noted that the stability of complexes with EDDS is lower than that of the corresponding complexes with EDTA due to the different size and number of chelated metallacycles. The obtained heteronuclear complexes belong to folded complexes, in which the ligand-complexone realizes the maximum denticity to the lanthanide ion, and the coordination sphere of the 3d-cation is formed by carboxyl groups EDTA / EDDS and inner-sphere water molecules. In this case, the ions of 3d-metals are in a distorted octahedral environment, and the coordination number of Pr(III) is 8.