In this work, the electronic and molecular structure, as well as the morphology, of innovative nanostructured materials whose optical properties respond to the presence of heavy metals in water samples was investigated. In particular, the here discussed silver nanoparticles (NPs) stabilized by a hydrophilic ligand (sodium 3-mercapto-1-propanesulfonate, 3MPS) are able to reveal the presence of mercury ions at ppm levels. The sensitivity of the proposed nanosensor to Hg(II) in 1−5 ppm range was ascertained by optical tests; then, the local chemistry and electronic structure of the nanostructured coordination compounds made of functionalized silver nanoparticles (NPs) and metal ions, and their correlation with the resulting nanoaggregates' shape and morphology, were investigated by state-of-the-art synchrotron radiation (SR)-induced spectroscopies and transmission electron microscopy (TEM). In particular, SR-induced X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) measurements allowed us to gather complementary information about the silver−mercury interaction, which is only partially mediated by the negatively charged 3MPS ligand, different from what was observed for analogous nanosensors applied to other bivalent heavy metal ions, for example, Co(II) and Ni(II). TEM morphological analysis sheds light on the structure of the AgNP-3MPS/Hg aggregates, revealing the formation of Ag/Hg alloy nanoparticles.

In this study, two new hexyl bis(pyrazol-1-yl) acetate ligands and the related copper(II) complexes were prepared and fully characterized in the solid state and in solution. Their electronic and molecular...

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, PPh 3 -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.

No abstract

Colossal electroresistance (CER) in manganites, i.e., a large change in electrical resistance under the influence of either an applied electric field or an applied electric current, has often been described as complimentary to the colossal magnetoresistance (CMR) effect. Mixed valent vanadates with active t 2g and empty e g orbitals, unlike manganites, have not naturally been discussed in this context, as double exchange based CMR is not realizable in them. However, presence of coupled spin and orbital degrees of freedom, metal-insulator transition (MIT) accompanied by orbital order-disorder transition, etc., anyway make the vanadates an exciting group of materials. Here we probe a Fe-doped hollandite lead vanadate PbFe 1.75 V 4.25 O 11 (PFVO), which exhibits a clear MIT as a function of temperature. Most importantly, a giant fall in the resistivity, indicative of a CER, as well as a systematic shift in the MIT towards higher temperature are observed as a function of applied electric current. Detailed structural, magnetic, thermodynamic and transport studies point towards a complex interplay between orbital order/disorder effect, MIT and double exchange in this system.