A series of neutral mixed-ligand [HB(pz)3]Ag(PR3) silver(I) complexes (PR3 = tertiary phosphine, [HB(pz)3]− = tris(pyrazolyl)borate anion), and the corresponding homoleptic [Ag(PR3)4]BF4 compounds have been synthesized and fully characterized. Silver compounds were screened for their antiproliferative activities against a wide panel of human cancer cells derived from solid tumors and endowed with different platinum drug sensitivity. Mixed-ligand complexes were generally more effective than the corresponding homoleptic derivatives, but the most active compounds were [HB(pz)3]Ag(PPh3) (5) and [Ag(PPh3)4]BF4 (10), both comprising the lipophilic PPh3 phosphine ligand. Detailed mechanistic studies revealed that both homoleptic and heteroleptic silver complexes strongly and selectively inhibit the selenoenzyme thioredoxin reductase both as isolated enzyme and in human ovarian cancer cells (half inhibition concentration values in the nanomolar range) causing the disruption of cellular thiol-redox homeostasis, and leading to apoptotic cell death. Moreover, for heteroleptic Ag(I) derivatives, an additional ability to damage nuclear DNA has been detected. These results confirm the importance of the type of silver ion coordinating ligands in affecting the biological behavior of the overall corresponding silver complexes, besides in terms of hydrophilic–lipophilic balance, also in terms of biological mechanism of action, such as interaction with DNA and/or thioredoxin reductase.

Partial substitution of molybdenum by sulfur on the solid solution La 2 Mo 2-y S y O 9 (0.1 � y � 0.3) is carried out by using the lanthanum oxysulfate (La 2 SO 6 ) via a solid-state reaction. Substitution rates are 5 mol % S, 10 mol % S and 15 mol % S. Structural and vibrational characteristics of La 2 Mo 2-y S y O 9 are revealed via XRD, thermal analysis, electrical properties as well as spectroscopic investigations. Results show the alteration of the reversible first order phase transition that commonly happens in La 2 Mo 2 O 9 at around 580 °C from a monoclinic ordered α form at low temperature to a cubic disordered β phase at high temperature. Crystallization of the studied LAMOX specimens occurs in the non-centrosymmetric space group P2 1 3. The sintered samples' annealing occurs at 850 °C and they are shaped into pellets for electrical properties determination. The Arrhenius law is activated below 580 °C. Above this thermal threshold, a Vogel Tamman Fulcher behavior is depicted. In addition, conductivity decreases in all samples as compared to the undoped composite. Ultimately, the observed vibrational modes in Raman and IR are assigned to the vibrations of molybdate MoO 4 2À and sulfate SO 4 2À groups.

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