In the exploration of new osmium based double perovskites, Sr2FeOsO6 is a new insertion in the existing family. The polycrystalline compound has been prepared by solid state synthesis from the respective binary oxides. Powder X-ray diffraction (PXRD) analysis shows the structure is pseudocubic at room temperature, whereas low-temperature synchrotron data refinements reveal the structure to be tetragonal, space group I4/m. Heat capacity and magnetic measurements of Sr2FeOsO6 indicated the presence of two magnetic phase transitions at T1 = 140 K and T2 = 67 K. Band structure calculations showed the compound as a narrow energy gap semiconductor, which supports the experimental results obtained from the resistivity measurements. The present study documents significant structural and electronic effects of substituting Fe(3+) for Cr(3+) ion in Sr2CrOsO6.

Reactions in solvothermal conditions between hexanuclear rare earth complexes and H2bdc, where H2bdc symbolizes terephthalic acid, lead to a family of monodimensional coordination polymers in which hexanuclear complexes act as metallic nodes. The hexanuclear cores can be either homometallic with general chemical formula [Ln6O(OH)8(NO3)6](2+) (Ln = Pr-Lu plus Y) or heterometallic with general chemical formula [Ln6xLn'6-6xO(OH)8(NO3)6](2+) (Ln and Ln' = Pr-Lu plus Y). Whatever the hexanuclear entity is, the resulting coordination polymer is iso-structural to [Y6O(OH)8(NO3)2(bdc)(Hbdc)2·2NO3·H2bdc]∞, a coordination polymer that we have previously reported. The random distribution of the lanthanide ions over the six metallic sites of the hexanuclear entities is demonstrated by (89)Y solid state NMR, X-ray diffraction (XRD), and luminescent measurements. The luminescent and colorimetric properties of selected compounds that belong to this family have been studied. These studies demonstrate that some of these compounds exhibit very promising optical properties and that there are two ways of modulating the luminescent properties: (i) playing with the composition of the heterohexanuclear entities or (ii) playing with the relative ratio between two different hexanuclear entities. This enables the independent tuning of luminescence intensity and color.

The key characteristic of single-molecule magnets (SMMs) is the anisotropy-induced blocking barrier, which should be as efficient as possible, i.e., to be able to provide long magnetic relaxation times at elevated temperatures. The strategy for the design of efficient SMMs on the basis of transition-metal complexes such as Mn12Ac is well established, which is not the case of complexes involving strongly anisotropic metal ions such as cobalt(II) and lanthanides (Ln). While strong intraionic anisotropy in the latter allows them to block the magnetization already in mononuclear complexes, the presence of several such ions in a complex does not result automatically in more efficient SMMs. Here, the magnetic blocking in the series of isostructural 3d-4f complexes Co(II)-Ln(III)-Co(II), Ln = Gd, Tb, and Dy, is analyzed using an originally developed ab initio based approach for the investigation of blocking barriers. The theoretical analysis allows one to explain the counterintuitive result that the Co-Gd-Co complex is a better SMM than terbium and dysprosium analogues. It turns out that the highly efficient magnetic blockage in the Co-Gd-Co complex results from a concomitant effect of unexpectedly large unquenched orbital momentum on Co(II) ions (ca. 1.7 μB) and the large spin on the gadolinium (S = (7)/2), which provides a multilevel blocking barrier, similar to the one of the classical Mn12Ac. We conclude that efficient SMMs could be obtained in complexes combining strongly anisotropic and isotropic metal ions with large angular momentum rather than in polynuclear compounds involving strongly anisotropic ions only.

Encapsulation of macrocyclic europium(III) chelates by discrete, monodisperse SiO2 nanoparticles (NPs) has been carried out, and the resulting significant enhancement of metal-derived luminescence has been studied to rationalize this dramatic effect. The tetraiminodiphenolate motif chosen for this study is easily synthesized and incorporated into the NP matrix under ambient conditions. The free complex exhibits primarily weak ligand-derived emission at room temperature, typical for these compounds, and displays intense metal-centered luminescence from the europium only when cooled to 77 K. Upon encapsulation by the NPs, however, europium-derived luminescence is visibly "turned on" at room temperature, yielding strong emission peaks characteristic of europium(III) with a corresponding enhancement factor of 6 × 10(6). The similar ligand singlet and triplet excited-state energies determined for the free complex (20820 and 17670 cm(-1), respectively) versus the encapsulated complex (20620 and 17730 cm(-1)) indicate that encapsulation does not affect the energy levels of the ligand appreciably. Instead, a detailed analysis of the metal-centered emission and ligand singlet and triplet emission bands for the free and encapsulated complexes reveals that the enhanced metal emission is due to the rigid environment afforded by the silica NP matrix affecting vibrationally mediated energy transfer. Further, the metal-centered emission lifetimes in methanol versus deuterated methanol indicate a decrease in the number of coordinated solvent molecules upon encapsulation, changing from an average of 3.3 to 2.1 bound methanol molecules and reducing the known quenching effect on europium-centered luminescence due to nearby OH vibrations.

A series of PTA and DAPTA platinum(II) and palladium(II) thionate complexes of the type trans-[M(SN)2P2] were prepared from the reaction of cis-[MCl2P2] [M = Pt, Pd; P = PTA (1,3,5-triaza-7-phosphaadamantane), DAPTA (3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane)] with the in situ generated sodium salts of the heterocyclic thiones S-m-methylpyrimidine-2-thione, S-4,6-dimethylpyrimidine-2-thione, S-4,6-dihydroxypyrimidine-2-thione, benzothiazole-2-thione, benzoxazole-2-thione, S-1,3,4,-thiadiazole-2-thione, S-4,5-H-thiazolan-2-thione, and S-pyrimidine-4(1H)-one-2-thione. The X-ray structures of six of the compounds confirm the trans disposition and, only in the case of [Pd2Cl2(S-pyrimidine-4(1H)-one-2-thionate)2(PTA)2], a dinuclear structure with a Pd-Pd distance of 3.0265(14)Å was observed. In vitro cytotoxicities against human ovarian cancer cell lines A2780 and A2780cisR were evaluated for ten complexes showing a high inhibition of cellular growth with a comparable inhibitory potency (IC50) against A2780 cells to that of cisplatin. Notably, the compounds also show significant (up to 7-fold higher) activity in cisplatin-resistant A2780cisR cell lines.

A series of seven-coordinate mononuclear lanthanide(III) complexes of the general formula [(TPP)Ln(LOEt)]·0.25H2O and [(Pc)Ln(LOEt)] (Ln(3+) = Dy(3+), Tb(3+), Ho(3+), and Gd(3+); TPP = 5,10,15,20-tetraphenylporphyrinate; Pc = phthalocyaninate; LOEt(-) = [(η(5)-C5H5)Co(P(=O)(OEt)2)3](-)) are synthesized on the basis of the tripodal ligand LOEt(-) and either porphyrin or phthalocyanine ligands. All of the complexes are characterized by X-ray crystallography and by static and dynamic magnetic measurements. The Dy and Tb complexes show the field-induced slow relaxation of magnetization, and they are interesting seven-coordinate single-lanthanide-based SMMs. The magnetic relaxation properties of these double-decker sandwich complexes are influenced by the local molecular symmetry and are sensitive to subtle distortions of the coordination geometry of the paramagnetic lanthanide ions, such as metal-to-plane distances, plane center distances, and bending angles.

The synthesis and characterization of a new series of neutral, six-coordinated mixed-ligand compounds [M(III)(PS)2(L)] (M = Re; (99)Tc), where PS is bis(arylalkyl)- or trialkylphosphinothiolate and L is dithiocarbamate, are reported. Stable [M(III)(PS)2(L)] complexes were easily synthesized, in good yield, starting from precursors where the metal was in different oxidation states (III, V, and VII), involving ligand-exchange and/or redox-substitution reactions. The compounds were characterized by elemental analysis, positive-ion electrospray ionization mass spectrometry, multinuclear NMR spectroscopy, cyclic voltammetry, and X-ray diffraction analysis. All complexes are constituted by the presence of the [M(III)(PS)2](+) moiety, where two phosphinothiolate ligands are tightly bound to the metal and the remaining two positions are saturated by a dithiocarbamate chelate, also carrying bulky bioactive molecules [e.g., (2-methoxyphenyl)piperazine]. X-ray analyses were performed on crystalline specimens of four different Re/(99)Tc compounds sharing a distorted trigonal-prismatic geometry, with a P2S4 coordination donor set. The possibility of easily preparing these [M(III)(PS)2(L)] complexes, starting from the corresponding permetalate anions, in mild reaction conditions and in high yield, lays the first stone to the preparation of a new series of M(III)-based (M = (99m)Tc/(188)Re) compounds potentially useful in theragnostic applications.

The derivatization of macromolecules with redox-stable groups is a challenge for molecular electronics applications. The large majority of redox-derivatized macromolecules involve ferrocenes, and there are only a few reports with cobalticinium. We report here the first click derivatization of macromolecules with the cobalticinium redox group using ethynylcobalticinium hexafluorophosphate, 1. Cu(I) catalysis was used for these selective click metallodendrimer syntheses starting from 1 and providing the tripodal dendron 3 that contains three 1,2,3-triazolylcobalticinium termini and a phenol focal point and the dendrimers of generations 0, 1, and 2 containing 9, 27, and 81 triazolylcobalticinium units for the dendrimers 4, 5, and 6, respectively. Atomic force microscopy (AFM) statistical studies provided the progression of height upon increase of dendrimer generation. Cyclic voltammetry studies in MeCN and dimethylformamide (DMF) show the solvent-dependent reversibility of the Co(III/II) wave (18e/19e) and generation dependent reversibility of the Co(II/I) (19e/20e) wave in DMF. The H2PO4(-) anion is only recognized by the largest metallodendrimer 6 by a significant cathodic shift of the Co(III/II) wave.

The reaction of the gold(I) complex [Au(SpyCOOH)(PPh3)], which contains nicotinic acid thiolate, with several amino acid esters such as glycine methyl ester or the enantiomerically pure l isomers of alanine methyl ester, phenylalanine methyl ester, valine methyl ester, methionine methyl ester, and proline methyl ester produces the gold(I) derivatives with the new thiolate containing amino acid ester ligands [Au{SpyCONHCH(R)COOMe}(PPh3)]. The reaction of these amino acid ester derivatives with LiOH in methanol and acidification with KHSO4 until pH 3-4 afford the corresponding acids, which are water-soluble species. These amino acid compounds can be further coupled with other amines, such as, for example, isopropylamine, to give the corresponding amide derivatives. The species with glycine methyl ester and valine methyl ester have been characterized by X-ray crystallography, showing, in the second case, only one of the enantiomers, which proves that retention of the configuration after reaction occurs.

The aryl amidoximes R'C6H4C(NH2)═NOH (R' = Me, 2a; H, 2b; CN, 2c; NO2, 2d) react with the dialkylcyanamide platinum(II) complexes trans-[PtCl2(NCNAlk2)2] (Alk2 = Me2, 1a; C5H10, 1b) in a 1:1 molar ratio in CHCl3 to form chelated mono-addition products [3a-h]Cl, viz. [PtCl(NCNAlk2){NH═C(NR2)ON═C(C6H4R')NH2}]Cl (Alk2 = Me2; R' = Me, a; H, b; CN, c; NO2, d; Alk2 = C5H10; R' = Me, e; H, f; CN, g; NO2, h). In the solution, these species spontaneously transform to the amidrazone complexes [PtCl2{NH═C(NR2)NC(C6H4R')NNH2}] (7a-h; 36-47%); this conversion proceeds more selectively (49-60% after column chromatography) in the presence of the base (PhCH2)3N. The observed reactivity pattern is specific for NCNAlk2 ligands, and it is not realized for conventional alkyl- and arylnitrile ligands. The mechanism of the cascade reaction was studied by trapping the isocyanate intermediates [PtCl(NCO){NH═C(NR2)NC(C6H4R')NNH2}] (5a-h) and also by ESI-MS identification of the ammonia complexes [PtCl(NH3){NH═C(NR2)NC(C6H4R')NNH2}](+) ([6a-h](+)) in solution. The complexes [3a]Cl, [3c-h]Cl, 5a-h and 7a-h were characterized by elemental analyses, high resolution ESI-MS, IR, and (1)H NMR techniques, while 5b, 5d, 5g, 7b, and 7e were also studied using single-crystal X-ray diffraction.