Die Reaktion von Lithiumfluorid mit den Trifluoriden der Lanthaniden und einiger Actiniden

Ino-Chloridolithates from Ionothermal Synthesis

Anionic lithium-containing species were predicted to impact ionic liquid-based electrochemical applications but have hitherto never been isolated from ionic liquid systems. Here, we report the first representatives of this class of compounds, ino-chloridolithates, comprising [LiCl₂]^- and [Li₂Cl₃]^- polyanions from ionothermal reactions. Such compounds are obtained at moderate temperatures with imidazolium-based ionic liquids and LiCl. The addition of an auxiliary ammonium salt enhances the lattice energy to yield an ammonium lithate in good yields, which enables extensive investigations including solid-state nuclear magnetic resonance, infrared, and Raman spectroscopy. The structural motifs of ino-lithates are related to ino-silicates, as 1D-extended anionic substructures are formed. Despite this analogy, according to density functional theory calculations with periodic boundary conditions, no evidence of covalent bonding in the anionic moieties is found-indicating packing effects to be the main cause for the formation. Based on an in-depth analysis of the different synthetic parameters, this class of compounds is discussed as an intermediate in ionic liquid applications and could serve as a model system for electrochemical lithium-based systems.

Giant and reversible low field magnetocaloric effect in LiHoF4 compound

Cryogenic refrigeration technology is gradually penetrating into increasing aspects of human life and industrial production. Magnetic refrigeration shows excellent application potential due to its high efficiency, good stability and environmental friendliness. It is important for a magnetic refrigeration system to secure a high-performance magnetocaloric material under a low applied magnetic field, which can greatly simplify the design and reduce the expense. In this study, LiHoF₄, a polycrystalline compound prepared by an improved solid-state reaction method undergoes a second-order phase transition below 2 K. Meanwhile, an unexpected giant low-field magnetocaloric effect has been observed. The maximum magnetic entropy changes are 11.0 J kg^-1 K^-1, 19.0 J kg^-1 K^-1, and 25.9 J kg^-1 K^-1 in field changes of 0.6 T, 1.0 T, and 2.0 T, respectively. The giant and reversible low field magnetocaloric effect proves it to be one of the most practical candidates among the cryogenic magnetic refrigerants.

Antitumoral Activity of Non-Platinum Xanthate Complexes

To establish structure-activity relationships, derivatives of bis(O-alkyldithiocarbonato)platinum(II) complexes were analyzed. Eighteen bis(O-alkyldithiocarbonato) metal complexes were synthesized, and their cytotoxic activity on two human cancer cell lines was compared with the corresponding platinum bis(O-alkyldithiocarbonato) complexes and cisplatin. Complexes were synthesized with palladium, gold, nickel, copper, rhodium, and bismuth. Palladium and bismuth complexes were found to display significant cytotoxic activity. Palladium complexes were most active with up to 10-fold lower IC50 values as compared with the corresponding platinum complexes. The other complexes were only poorly active. Palladium, bismuth, and nickel complexes were more active at pH 6.8 than at pH 7.4. This difference in activity was most pronounced with palladium complexes. A pH of 6.8 and lower has been frequently found in solid tumors. Drugs with such pH dependent activity are supposed to have an improved therapeutic index as compared to drugs that are active irrespective of pH.

Synthesis and structure-activity relationship of novel antitumoral platinum xanthate complexes

To establish structure-activity relationships, derivatives of a recently described sulfur-containing antitumoral platinum complex, bis(O-ethyldithiocarbonato)platinum(II), named thioplatin, were analyzed. Twenty different bis(O-alkyldithiocarbonato)platinum(II) complexes were synthesized and tested for cytotoxic activity in a panel of six human tumor lines. Derivatives with up to 7-fold increased activity compared to thioplatin and up to 25-fold more activity than cisplatin were identified. Bis(O-alkyldithiocarbonato)platinum(II) complexes with short n-alkyl chains such as methyl, ethyl, propyl, and butyl were found to be superior to compounds with long n-alkyl chains such as hexyl, octyl, and decyl. Complexes derived from secondary xanthates displayed significantly higher activity than those derived from primary xanthates with the same number of C atoms. Like thioplatin, all tested platinum complexes were more active at pH 6.8 than at pH 7.4. A pH of 6.8 and lower has been frequently found in solid tumors because of the tendency of tumor cells to undergo anaerobic fermentation. Drugs with such pH-dependent antitumoral activity have an improved therapeutic index compared to drugs that are active irrespective of pH.