Gabriela Marinescu

A new synthetic route towards binuclear 3d–4f complexes, using non-compartmental ligands derived from o-vanillin. Syntheses, crystal structures, magnetic and luminescent properties

Sixteen new 3d–4f binuclear complexes have been obtained using two Schiff-base ligands, Hvalampy and Hvalaepy, derived from the reaction of o-vanillin and 2-aminomethyl-pyridine or 2-(2-aminoethyl)-pyridine, respectively. Hvalaepy ligand: [Zn(valaepy)2Sm(O2NO)3]·CH3CN 1; [Ni(valaepy)2Eu(O2NO)3(H2O)]·CH3CN 2; [Ni(valaepy)2Gd(O2NO)3(H2O)]·CH3CN 3; [Ni(valaepy)2Dy(O2NO)3(H2O)]·CH3CN 4; [Ni(valaepy)2Ho(O2NO)3(H2O)]·CH3CN 5; [Cu(valaepy)2Eu(O2NO)3]·CH3CN 6; [Cu(valaepy)2Gd(O2NO)3]·CH3CN 7; Hvalampy ligand: [Zn(valampy)2Pr(O2NO)3]·CH3CN 8, [Zn(valampy)2Sm(O2NO)3]·CH3CN 9; [Zn(valampy)2Gd(O2NO)3]·CH3CN 10; [Zn(valampy)2Tb(O2NO)3]·CH3CN 11; [Zn(valampy)2Dy(O2NO)3]·CH3CN 12; [Zn(valampy)2Eu(O2NO)3]·CH3CN 13; [Ni(valampy)2La(O2NO)3(H2O)2]·2H2O 14, [Ni(valampy)2Sm(O2NO)3(H2O)2]·2H2O 15; [Ni(valampy)2Eu(O2NO)3(H2O)]·2CH3CN 16. The crystal structures of the sixteen compounds can be described as resulting from the coordination of two valaepy− (or valampy−) ligands to the 3d metal ions through two phenoxo oxygen atoms and nitrogen atoms, arising from the pyridyl and azomethynic groups. In all these compounds the 3d and 4f metal ions are bridged by the phenoxo oxygen atoms. The comparative analysis of the crystal structures shows several differences, which arise mainly from the stereochemical preference of the 3d metal ions. These ions arrange the two organic ligands in positions that favour or not the coordination of the methoxy groups to the lanthanide ions. The magnetic properties of compounds 2, 3, 4, 5, 7, 14, 15, and 16 have been investigated. The exchange interactions between NiII and GdIII in 3, and between CuII and GdIII in 7 were found to be ferromagnetic (JNiGd = 1.56 cm−1; JCuGd = 4.94 cm−1; H = −JSGdSM). For the 3d–4f binuclear complexes derived from the Hvalampy ligand (namely 8–13) the photoluminescence (PL) properties were investigated in the Vis spectral region. The results provide evidence for the relatively stronger antenna effect in 9 and 11 compared to 8, 12 and 13.

Polynuclear coordination compounds as precursors for CuFe2O4

The possibility of obtaining copper ferrite through the thermal decomposition of the two polynuclear coordination compounds: (NH4)8[Fe2Cu(C2O4)8] n(I) and [Fe2Cu(C2O4)2(OH)4]·4H2O (II) was considered. The polynuclear compounds were characterized by various physical chemical techniques, e.g., IR, UV-VIS, EPR, Mossbauer spectra, thermal analysis and magnetic measurements. The final products obtained after thermal decomposition of the complex compounds were analysed by X-ray diffraction. A mixture of tetragonal CuFe2O4, α-Fe2O3 and CuO is generated from the thermolysis of compound I, while a clean tetragonal CuFe2O4 with saturation magnetization of 26.89 emu g−1 is obtained from compound II.

New heterometallic coordination polymers based on zinc(II) complexes with Schiff-base ligands and dicyanometallates: synthesis, crystal structures, and luminescent properties

Four new d10 heterometallic coordination polymers have been obtained using three Schiff-base ligands, zinc(II) nitrate, and dicyanometallates: 1∞[{Zn3(Salen)2}{μ-Au(CN)2}2] (1); 1∞[Zn(Saldmen){μ-Ag(CN)2}]·2H2O (2); 1∞[Zn(Salampy){μ-Ag(CN)2}] (3); 1∞[Zn(Salampy){μ-Au(CN)2}] (4). The Schiff bases are obtained from condensation of salicylaldehyde with ethylenediamine (H2Salen); N,N-dimethyl-ethylenediamine (HSaldmen) and, respectively, 2-aminomethyl-pyridine (HSalampy). The dicyanometallates are K[Ag(CN)2] and K[Au(CN)2]. The compounds were characterized by X-ray single-crystal diffraction, infrared spectroscopy, UV–vis spectroscopy, and elemental analysis. In compound 1, the homotrimetallic units, {Zn3(salen)2}2+, are connected by two [Au(CN)2]− bridges, forming a 1-D double chain. In compounds 2–4, the crystal structures show polymeric zigzag chains generated by the mononuclear zinc(II) nodes and [M(CN)2]− spacers. The luminescence properties of the new heterometallic polymers have also been investigated. The self-assembly processes between homotrimetallic, {Zn3(salen)2}2+, and mononuclear, {Zn(Saldmen)}+, {Zn(Salampy)}+, units and dicyanometallates, generate new polymeric 1-D chains. In compound 1 the homotrimetallic units, {Zn3(salen)2}2+, are connected by two [Au(CN)2]− bridges, forming 1-D double chain. In compounds 2–4 the crystal structures show polymeric 1-D chains generated by the mononuclear zinc(II) nodes and [M(CN)2]− spacers.

Metal Zn(II), Cu(II), Ni (II) complexes of ursodeoxycholic acid as putative anticancer agents

The aim of the study was to evaluate the influence of metal [Zn(II), Cu(II), Ni(II)] complexes with ursodeoxycholic acid (UDCA) on the viability and proliferation of tumour and non-tumour cells. Cell lines established from retrovirus-transformed chicken hepatoma (LSCC-SF-Mc29) and rat sarcoma (LSR-SF-SR) as well as from human cancers of the breast (MCF-7), uterine cervix (HeLa), lung (A549) and liver (HepG2) were used as model systems. Non-tumour human embryo (Lep-3) cells were also included in some of the experiments. The investigations were carried out by the thiazolyl blue tetrazolium bromide (MTT) test, neutral red uptake cytotoxicity assay, crystal violet staining, double staining with acridine orange and propidium iodide and the colony-forming method. The results obtained revealed that: (1) UDCA and its metal complexes in the tested concentrations decreased (to a varying degree) the viability and proliferation of the treated cells in a time- and concentration-dependent manner; (2) chicken hepatoma (LSCC-SF-Mc29) cells were most sensitive to the cytotoxic and antiproliferative action of the compounds tested, followed by rat sarcoma (LSR-SF-SR) cells; (3) Cu‒UDCA and Ni‒UDCA were more effective against animal LSCC-SF-Mc29 and LSR-SF-SR cells, while Zn‒UDCA significantly decreased the viability and proliferation of human tumour cell lines; (4) applied independently, UDCA expressed lower cytotoxic/cytostatic activity as compared to metal complexes; and (5) the sensitivity of the non-tumour embryonic Lep-3 cells to the effects of UDCA and its metal complexes was comparable or even higher than those of the human tumour cells.

Multifunctional Silver Nanoparticles-Decorated Silica Functionalized with Retinoic Acid with Anti-Proliferative and Antimicrobial Properties

The paper describes a rapid and simple method for preparing a multifunctional biomaterial based on retinoic acid covalently bound on silica@Ag particles. Monodispersed SiO2 particles were prepared by Stöber method and further used for loading the Ag nanoparticles on their surface. This composite was further functionalized with retinoic acid. Characterization of the hybrid materials was made by UV–Visible spectroscopy, Transmission electron microscopy, Scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and Thermal analysis. The biological evaluation of the obtained materials revealed their potential use for multiple biomedical applications, from anti-proliferative agents to novel antimicrobial and antibiofilm strategies.

Synthesis and Characterization of Chitosan-Coated Cobalt Ferrite Nanoparticles and Their Antimicrobial Activity

Chitosan-coated cobalt ferrites were synthesized by wet ferritization method through two different approaches. The nanostructured chitosan-coated cobalt ferrites were characterized by: X-ray diffraction (XRD), scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM/HR-TEM), thermal analysis, infrared spectroscopy (IR) and Mössbauer spectroscopy. X-ray diffraction patterns confirmed the formation of CoFe2O4 cubic spinel structure with an average crystallite size of 1.75 and 5.5xa0nm, respectively. Mössbauer spectra consist in a central quadrupole pattern. The deconvolution in the hypothesis of Lorentzian line shape evidences the prevailing presence of Fe3+ ions at the nanoparticle surface. The antimicrobial activity of chitosan-coated cobalt ferrites against Gram-positive and Gram-negative bacteria, as well as fungal strains was investigated. Based on the results, chitosan-coated cobalt ferrites are thought to be suitable candidates for the development of novel anti-biofilm agents.

CoFe2−xCrxO4 ferrites: synthesis, characterization and their catalytic activity

Chromium substituted cobalt ferrites CoFe2−xCrxO4 (xu2009=u20090; 1; 1.5) were synthesized through a soft chemistry method—the gluconate precursor route. The gluconate precursors were characterized by infrared spectroscopy (IR), ultraviolet–visible spectroscopy and thermal analysis. The spinel oxide powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy and Brunauer–Emmett–Teller N2 adsorption–desorption analyses. XRD indicated the formation of the spinel-type phase with good crystallinity. The mean crystalline domains size decreased from 23.8 to 17.8xa0nm with the increase in the chromium content. SEM revealed faceted particles for which the particle sizes varied significantly with the chromium content. The chromium substituted cobalt ferrites were found to have high catalytic performance.

3d metal complexes with meloxicam as therapeutic agents in the fight against human glioblastoma multiforme and cervical carcinoma

The aim of our study was to evaluate the influence of selective non-steroidal anti-inflammatory drug meloxicam and its metal (Cu(II), Zn(II), Co(II), Ni(II)) complexes on the viability and proliferation of cultured humancarcinoma of the uterine cervix (HeLa) and glioblastoma multiforme (8MGBA) cells. The investigations were performed by short-term (24 h–96 h, with monolayer cultures) and long-term (16 d, with three-dimensional colonies of cancer cells) experiments by using methods with different molecular/cellular targets and mechanisms of action, such as thiazolyl blue tetrazolium bromide (MTT) test, neutral red uptake cytotoxicity assay, crystal violet staining, double staining with acridine orange and propidium iodide, alkaline version of single cell gel electrophoresis (comet assay) and colony-forming technique. The obtained results revealed that the application of the examined compounds at concentrations ranging from 5 µg/mL to 500 µg/mL induced cytopathological changes, including DNA damages in the treated cells and a significant decrease of their viability and proliferation in a time- and concentration-dependent manner. Metal complexes were found to have a more pronounced cytotoxic/cytostatic effect, when compared to their ligand meloxicam.