ABSTRACT
Bis(pyrazol-1-yl)- and bis(3,5-dimethylpyrazol-1-yl)-acetates were conjugated with the 2-hydroxyethylester and 2-aminoethylamide derivatives of the antineoplastic drug lonidamine to prepare Cu(I) and Cu(II) complexes that might act through synergistic mechanisms of action due to the presence of lonidamine and copper in the same chemical entity. Synchrotron radiation-based complementary techniques [X-ray photorlectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS)] were used to characterize the electronic and molecular structures of the complexes and the local structure around the copper ion (XAFS) in selected complexes. All complexes showed significant antitumor activity, proving to be more effective than the reference drug cisplatin in a panel of human tumor cell lines, and were able to overcome oxaliplatin and multidrug resistance. Noticeably, these Cu complexes appeared much more effective than cisplatin against 3D spheroids of pancreatic PSN-1 cancer cells; among these, PPh3-containing Cu(I) complex 15 appeared to be the most promising derivative. Mechanistic studies revealed that 15 induced cancer cell death by means of an apoptosis-alternative cell death.
Subject(s)
Antineoplastic Agents , Coordination Complexes , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Coordination Complexes/chemistry , Coordination Complexes/pharmacology , Copper/chemistry , Copper/pharmacology , Crystallography, X-Ray , Humans , Indazoles , Ligands , Molecular StructureABSTRACT
We have investigated magnetic, structural and dielectric properties of Bi5FeTi3O15(BFTO) in the temperature range 5K-300 K. Using diffraction, Raman spectroscopy and x-ray absorption fine structure measurements, iso-structural modifications are observed at low temperatures (≈100 K). The analysis of dielectric constant data revealed signatures of dielectric relaxation, concomitant with these structural modifications in BFTO at the same temperatures. Further, employing complementary experimental methods, it is shown that the distribution of Fe/Ti ions in BFTO is random. With the help of techniques that probe magnetism at various length and time scales, it is shown that the phase-pure BFTO is non-magnetic down to the lowest temperatures.
ABSTRACT
In this study, two new hexyl bis(pyrazol-1-yl)acetate ligands and related copper(ii) complexes were prepared and fully characterized in the solid state and in solution. Their electronic and molecular structures were investigated by X-ray photoelectron spectroscopy and near edge X-ray absorption; their ligand molecular structural stability upon coordination to copper was also investigated. The Cu(ii) complexes were studied as new catalysts in copper-catalyzed C-H oxidation for allylic functionalization (the Kharasch-Sosnovsky reaction) avoiding the use of any external reducing agents. Using 5 mol% of these catalysts and tert-butylperoxybenzoate as the oxidant, allylic benzoates were obtained in up to 90% yield: the general reaction time was decreased to 6 h and a 5 to 1 ratio of the alkene and tert-butylperoxybenzoate was used to overcome the two most important limitations on their use in chemistry.
ABSTRACT
The present work is aimed at exploring the local atomic structure modifications related to the spin reorientation transition (SRT) in DyFeO3 orthoferrite exploiting x-ray absorption fine structure (XAFS) spectroscopy. For this purpose we studied by XAFS the evolution of the local atomic structure around Fe and Dy as function of temperature (10-300 K) in a DyFeO3 sample having the SRT around 50-100 K. For sake of comparison we studied a YFeO3 sample having no SRT. The analysis of the extended region has revealed an anomalous trend of Fe-O nearest neighbour distribution in DFO revealing (i) a weak but significant compression with increasing temperature above the SRT and (ii) a peculiar behavior of mean square relative displacement (MSRD) [[Formula: see text]] of Fe-O bonds showing an additional static contribution in the low temperature region, below the SRT. These effects are absent in the YFO sample supporting these anomalies related to the SRT. Interestingly the analysis of Dy L 3-edge data also reveal anomalies in the Dy-O neighbour distribution associated to the SRT, pointing out a role of magnetic Re ions across [Formula: see text]. These results point out micro-structural modification at both Fe and Dy sites associated to the magnetic transitions in DFO, it can be stated in general terms that such local distortions across [Formula: see text] and magnetic Re3+ may be present in other orthoferrites exhibiting multiferroic nature.
