Revisiting the Assignment of Innocent and Non-Innocent Counter ions in Lanthanide(III) Solution Chemistry

Lanthanides are found in critical applications from display technology to renewable energy. Often these rare earth elements are used as alloys or functional materials, yet the access to them are trough solution processes. In aqueous solution the rare earths are found predominantly as trivalent ions and charge balance dictates that counter ions are present. The fast ligand exchange and lack of directional bonding in lanthanides complexes has led to questions regarding the speciation of Ln3+ solvates in the presence of various counter ions, and to the distinction between innocent = non-coordinating, and non-innocent = coordinating counter ions. There is limited agreement as to which counter ions that belong to each group, which lead to this report. By using Eu3+ luminescence, it was possible to clearly distinguish between coordinating and non-coordinating ions. To interpret the results it was required to bridge the descriptions of ion pairing and coordination. The da-ta—in form of Eu3+ luminescence spectra and luminescence lifetimes from solutions with varying concentrations of acetate, chloride, nitrate, fluoride, sulfate, perchlorate and triflate—were contrasted to those obtained with ethylenediaminetet-raaceticacid (EDTA), which allowed for the distinction between three Ln3+-anion interaction types. It was possible to con-clude which counter ions are truly innocent (e.g. ClO4- and OTf-), and which clearly coordinate (e.g. NO3- and AcO-). Finally, the considerate amount of data from systems studied under similar conditions allowed the minimum perturbation arising from inner sphere or outer sphere coordination in Eu3+ complexes to be identified.

Spectral Study of Some Lanthanides Complexes with Quaternary Pyridinium Ligands

Some lanthanides complexes with two N-heterocyclic ligands derived from 4,4`-bipyridinium and 1,2-bis-(4-pyridinium) ethane (noted BP and BPE) were studied in presence of triethylamine and methanol in view of their application as cytotoxic agents. Absorption spectra have been recorded by UV-Vis spectroscopy during the complexation process in solution. The ligands demonstrate preferential arrangements in lanthanide�s electronic structure which is identified much clearly in ultraviolet range. La(III)-BP solution indicates absorption at lmax= 206 nm while La(III)-BPE at lmax of 208 nm. The solution from the Nd(III)-BPE complex synthesis shows the highest absorbance at lmax= 220 nm, compared with Nd(III)-BP at lmax= 212 nm. The bathochromic shifts of the spectral bands can be assigned to the physical interaction of Ln(III) ions with ligands. No major changes were observed in the absorption, hypsochromic and hyperchromic effects when varying the ligand. The complexes spectral properties were performed by dissolving them in methanol in three phases until a complete dissolution of the precipitates was achieved.

Phenalenyl-based mononuclear dysprosium complexes

The phenalenyl-based dysprosium complexes [Dy(PLN)2(HPLN)Cl(EtOH)] (1), [Dy(PLN)3(HPLN)]·[Dy(PLN)3(EtOH)]·2EtOH (2) and [Dy(PLN)3(H2O)2]·H2O (3), HPLN being 9-hydroxy-1H-phenalen-1-one, have been synthesized. All compounds were fully characterized by means of single crystal X-ray analysis, paramagnetic 1H NMR, MALDI-TOF mass spectrometry, UV–vis spectrophotometry and magnetic measurements. Both static (dc) and dynamic (ac) magnetic properties of these complexes have been investigated, showing slow relaxation of magnetization, indicative of single molecule magnet (SMM) behavior. Attempts to synthesize sublimable phenalenyl-based dysprosium complexes have been made by implementing a synthetic strategy under anhydrous conditions. The sublimed species were characterized and their thermal stability was confirmed. This opens up the possibility to deposit phenalenyl-based lanthanides complexes by sublimation onto surfaces, an important prerequisite for ongoing studies in molecular spintronics.

Thermally Stable Encapsulation Material Based on Green and Red Lanthanide Phosphor for White Light Emitting Diodes

This study reported thermal stability of hybrid sol-gel encapsulation materials doped with lanthanides complexes for generating white light. Red and green lanthanide phosphor, Eu (tta)3phen and Tb (4DBBA)3TPPO were incorporated into VTES:TEOS hybrid sol-gel and dispensed into 360 nm to 390 nm UV LED packages. Thermal properties of developed encapsulation material were analysed by TGA. A thermal aging test up to 96 hours was done to check the stability of developed encapsulation material towards UV LED junction temperature of 120°C and the luminescence properties changes was observed using photoluminescence measurement. To check the encapsulation material stability on forward voltage, the operation voltage has been increased from 3.0V to 4.0V. The photometric measurement were recorded using integrating sphere for the properties of Colour Rendering Index (CRI), colour temperature and Commission Internationale de L’Eclairge (CIE) colour coordinates. Based on the results, developed encapsulation material produced white colour with CIE colour coordinate of (0.32, 0.35), CRI up to 75 and colour temperature around 6000K.