Slow Magnetic Relaxation in {[CoCxAPy)] 2.15 H2O}n MOF Built from Ladder-Structured 2D Layers with Dimeric SMM Rungs.

We present the magnetic properties of the metal-organic framework {[CoCxAPy]·2.15 H2O}n (Cx = bis(carboxypropyl)tetramethyldisiloxane; APy = 4,4`-azopyridine) (1) that builds up from the stacking of 2D coordination polymers. The 2D-coordination polymer in the bc plane is formed by the adjacent bonding of [CoCxAPy] 1D two-leg ladders with Co dimer rungs, running parallel to the c-axis. The crystal packing of 2D layers shows the presence of infinite channels running along the c crystallographic axis, which accommodate the disordered solvate molecules. The Co(II) is six-coordinated in a distorted octahedral geometry, where the equatorial plane is occupied by four carboxylate oxygen atoms. Two nitrogen atoms from APy ligands are coordinated in apical positions. The single-ion magnetic anisotropy has been determined by low temperature EPR and magnetization measurements on an isostructural compound {[Zn0.8Co0.2CxAPy]·1.5 CH3OH}n (2). The results show that the Co(II) ion has orthorhombic anisotropy with the hard-axis direction in the C2V main axis, lying the easy axis in the distorted octahedron equatorial plane, as predicted by the ab initio calculations of the g-tensor. Magnetic and heat capacity properties at very low temperatures are rationalized within a S* = 1/2 magnetic dimer model with anisotropic antiferromagnetic interaction. The magnetic dimer exhibits slow relaxation of the magnetization (SMM) below 6 K in applied field, with a tlf ≈ 2 s direct process at low frequencies, and an Orbach process at higher frequencies with U/kB = 6.7 ± 0.5 K. This compound represents a singular SMM MOF built-up of Co-dimers with an anisotropic exchange interaction.

Effect of TAT-DOX-PEG irradiated gold nanoparticles conjugates on human osteosarcoma cells.

The paper aims to investigate the cytotoxic effect on tumor cells of irradiated AuNPs in green light and subsequently functionalized with HS-PEG-NH2. The toxicity level of gold conjugates after their functionalization with DOX and TAT peptide was also evaluated. The AuNPs were prepared using the modified Turkevich method and exposed to visible light at a wavelength of 520 nm prior their PEGylation. The optical properties were analyzed by UV-vis spectroscopy, the surface modification was investigated using FTIR and XPS spectroscopies and their sizes and morphologies were evaluated by TEM and DLS techniques. DOX and TAT peptide were linked to the surface of PEGylated AuNPs by reacting their amino groups with glycidyloxypropyl of PEGylated DOX or TAT conjugates under mild conditions at room temperature and in the presence of ethanol as catalyst. The conjugates containing DOX or DOX and TAT have been characterized by fluorescence and FTIR techniques. The changes of electrochemical features were observed using cyclic voltammetry, suggesting a better stability of irradiated nanoparticles. By mass spectrometry it was confirmed that the compounds of interest were obtained. The cell viability test showed that irradiated and non-irradiated nanoparticles coated with PEG are not toxic in normal cells. Tumor cell viability analysis showed that the PEGylated nanoparticles modified with DOX and TAT peptide were more effective than pristine DOX, indicating cytotoxicity up to 10% higher than non-irradiated ones.

New Iminodiacetate-Thiosemicarbazone Hybrids and Their Copper(II) Complexes Are Potential Ribonucleotide Reductase R2 Inhibitors with High Antiproliferative Activity.

As ribonucleotide reductase (RNR) plays a crucial role in nucleic acid metabolism, it is an important target for anticancer therapy. The thiosemicarbazone Triapine is an efficient R2 inhibitor, which has entered ∼20 clinical trials. Thiosemicarbazones are supposed to exert their biological effects through effectively binding transition-metal ions. In this study, six iminodiacetate-thiosemicarbazones able to form transition-metal complexes, as well as six dicopper(II) complexes, were synthesized and fully characterized by analytical, spectroscopic techniques (IR, UV-vis; 1H and 13C NMR), electrospray ionization mass spectrometry, and X-ray diffraction. The antiproliferative effects were examined in several human cancer and one noncancerous cell lines. Several of the compounds showed high cytotoxicity and marked selectivity for cancer cells. On the basis of this, and on molecular docking calculations one lead dicopper(II) complex and one thiosemicarbazone were chosen for in vitro analysis as potential R2 inhibitors. Their interaction with R2 and effect on the Fe(III)2-Y· cofactor were characterized by microscale thermophoresis, and two spectroscopic techniques, namely, electron paramagnetic resonance and UV-vis spectroscopy. Our findings suggest that several of the synthesized proligands and copper(II) complexes are effective antiproliferative agents in several cancer cell lines, targeting RNR, which deserve further investigation as potential anticancer drugs.