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We present a Raman spectroscopy study of the vibrational properties of free-base meso-tetra(4-pyridyl) porphyrin polycrystals under various temperature and hydrostatic pressure conditions. The combination of experimental results and Density Functional Theory (DFT) calculations allows us to assign most of the observed Raman bands. The modifications in the Raman spectra when excited with 488   n m and 532   n m laser lights indicate that a resonance effect in the Q y band is taking place. The pressure-dependent results show that the resonance conditions change with increasing pressure, probably due to the shift of the electronic transitions. The temperature-dependent results show that the relative intensities of the Raman modes change at low temperatures, while no frequency shifts are observed. The experimental and theoretical analysis presented here suggest that these molecules are well represented by the C 2 v point symmetry group. [ABSTRACT FROM AUTHOR]

Four new Cu/PPh3/naphtoquinone complexes were synthesized, characterized (IR, UV/visible, 1D/2D NMR, mass spectrometry, elemental analysis, and X-ray diffraction), and evaluated as anticancer agents. We also investigated the reactive oxygen species (ROS) generation capacity of complex 4, considering the well-established photochemical property of naphthoquinones. Therefore, employing the electron paramagnetic resonance (EPR) "spin trap", 5,5-dimethyl-1-pyrroline N-oxide (DMPO) technique, we identified the formation of the characteristic •OOH species (hydroperoxyl radical) adduct even before irradiating the solution containing complex 4. As the irradiation progressed, this radical species gradually diminished, primarily giving rise to a novel species known as •DMPO-OH (DMPO + •OH radical). These findings strongly suggest that Cu(I)/PPh3/naphthoquinone complexes can generate ROS, even in the absence of irradiation, potentially intensifying their cytotoxic effect on tumor cells. Interpretation of the in vitro cytotoxicity data of the Cu(I) complexes considered their stability in cell culture medium. All of the complexes were cytotoxic to the lung (A549) and breast tumor cell lines (MDA-MB-231 and MCF-7). However, the higher toxicity for the lung (MRC5) and breast (MCF-10A) non-tumoral cells resulted in a low selectivity index. The morphological analysis of MDA-MB-231 cells treated with the complexes showed that they could cause decreased cell density, loss of cell morphology, and loss of cell adhesion, mainly with concentrations higher than the inhibitory concentration of 50% of cell viability (IC50) values. Similarly, the clonogenic survivance of these cells was affected only with concentrations higher than the IC50 values. An antimigratory effect was observed for complexes 1 and 4, showing around 20–40% of inhibition of wound closure in the wound healing experiments. [ABSTRACT FROM AUTHOR]

Herein, we report on the synthesis and characterization of ruthenium compounds with the general formula [RuCl(AA-H)(NO)(dppb]PF6, where AA = glycine (1), L-alanine (2), L-phenylalanine (3) and L-valine (4), and dppb = 1,4-bis(diphenylphosphine)butane. The complexes were characterized using elemental analysis, UV/Vis and infrared spectroscopies, 1H, 13C, 31P NMR techniques, and cyclic voltammetry. Furthermore, the structures of the compounds (1) and (3) were determined using single-crystal X-ray diffraction. In vitro evaluation of the Ru(II)/nitrosyl/amino acid complexes revealed their cytotoxic activities against triple-negative MDA-MB-231 breast cancer cells, and against the non-tumor murine fibroblast cells. All the compounds decreased the percentage of viable cells, inducing cell death by apoptosis. Additionally, the Ru(II) complexes inhibited the migration of MDA-MB-231 cells at concentrations lower than 35 µM, after 48 h of exposure. Thus, these complexes may be promising agents for the treatment of triple-negative MDA-MB-231 breast cancer. [ABSTRACT FROM AUTHOR]

A series of six ferrocene derivatives containing a semicarbazone or thiosemicarbazone side chain was investigated by cyclic voltammetry and positron annihilation lifetime measurements. Both the redox and the electron capture processes took place on the Fe atom. Correlations between the two methods were proposed, taking into account the substituents on the side chain of the compounds, their redox potentials and the probabilities of o-positronium (o-Ps).formation.

The [(DMSO)2H]trans-[RuCl4 (DMSO)2] complex presents an axial symmetry in the solid state and its EPR spectrum shows two g values (g^ or = 2,35 e g// or = 1,87). The complex [NH4]trans-[RuCl4(DMSO) 2] presents only one-g value in the solid state EPR spectrum indicating coupling of micro-aggregates. In a fresh solution of MeOH it is possible to detect the [NH4]trans-[RuCl4(DMSO)(MeOH)] and [RuCl3(DMSO)(MeOH)2] by EPR. After approximately 15 h only the latter complex is detected in solution. These species are also detected by cyclic voltammetry and the [RuCl2(DMSO)(MeOH)3] complex is generated electrochemically from [RuCl3(DMSO)(MeOH)2]. The [pyH]trans-[RuCl4(DMSO)(py)] was obtained from the reaction of [(DMSO)2H]trans-[RuCl4(DMSO) 2] with py, and was crystallized in the space group P (No.2), Z=2 with a=7.7608(1), b=8.5451(1), c=15.095(5)Å, beta=79.33(2)º. The structure was solved by Patterson and difference Fourier techniques and refined to R = 0.0886. EPR (T = -160 ºC) data confirmed the presence of the paramagnetically active Ru(III), consistent with the axial symmetry of the complex. The cyclic voltamogram of the pyridine complex shows a redox potential with E1/2 = - 0.15 V (vs. Ag/AgCl).

Nitric Oxide has been shown to be involved in many important biological functions. It serves as a vasodilator and a neurotransmitter in the brain and peripheral nervous system. It is also involved in the bacteria-killing process by macrophages. In this review we will discuss progress in nitric oxide chemistry and we will also attempt to explain its action in the cardiovascular, nervous and immune systems.

In coordination chemistry the study of geometrical isomerization and reactivity of specific isomers is a topic of major importance. The preparation of specific isomers often requires considerable complexity, and it is important to acquire a sense of what is involved in studying isomerism in laboratory. If it is difficult sometimes to prepare pure isomers, it is not easier to understand the mechanisms of isomerization reactions since studies on this subject have shown conflicting results and diferent interpretations on the same system have been reported in the literature. Although cis-trans isomerism in octahedral metal complexes is a common occurrence, there are relatively few studies reporting how these isomerizations occur. This paper gives an overview on cis-trans isomerization processes and identification of these species.

Described are the synthesis and characterization of Ru(II) complexes of the type Ru[Cl.sub.2][L.sub.2](N-O), where [L.sub.2] is either 1,4-bis (diphenylphosphino)butane (dppb) or [(P[Ph.sub.3]).sub.2], and N-O represents chelated 2-benzoylpyridine (2-bzpy) or 2-acetylpyridine (2-acpy); the Ru presursors used were [Ru[Cl.sub.2][(dppb)].sub.2] ([mu]-dppb) or Ru[Cl.sub.2][(P[Ph.sub.3]).sub.3]. The crystal structure of cis-Ru[C1.sub.2](dppb)(2-bzpy) is presented, and three other Ru[Cl.sub.2][L.sub.2](N-O) complexes with cis-chlorines are isolated and characterized spectroscopically; of the trans-dichloro species, Ru[Cl.sub.2][(P[Ph.sub.3]).sub.2](N-O) complexes are isolated, while the corresponding dppb species are characterized in situ. In all cases, thermodynamically stable cis-complexes are formed from initially formed trans-species. Key words: ruthenium, phosphines, 2-benzoylpyridine, 2-acetylpyridine, X-ray structures.

The ruthenium(II) complex, [Ru[Cl.sub.2](NO)L] (I), (L = [[(2-py).sub.2]P[C.sub.2][H.sub.4]P[O.sub.2](2-py)]-) was obtained from recrystallization of Ru[Cl.sub.3]NO(d2pype) (d2pype = [(2-py).sub.2]P[C.sub.2][H.sub.4]P[(2-py).sub.2]) in the presence of HN[O.sub.3], crystallizing in the monoclinic space group [P2.sub.1] (no. 4), with a = 8.012(4) [Angstrom], b = 14.454(4) [Angstrom], c = 9.353(3) [Angstrom], [beta] = 105.77(3)[degrees], and Z = 2. Crystals of the DMSO solvate of the complex (II) were obtained from [(C[D.sub.3]).sub.2]SO solution, crystallizing in the monoclinic space group [P2.sub.1]/c (no.14) with a = 9.7080(2) [Angstrom], b = 22.2920(5) [Angstrom], c = 11.5230(3) [Angstrom], [beta] = 92.0450(10)[degrees], and Z = 4. In both complexes, the geometry about the ruthenium atom is a distorted octahedron mainly as a result of the tridentate [P,N,O]-bonding mode of L. The v (NO) bands at 1875 [cm.sup-1] in both complexes are consistent with the linear disposition of the NO group and the Ru atom as is observed in the X-ray crystal structure (Ru-N1-O1 angle = 178.5(4)[degrees]). Key words: pyridylphosphine, nitrosyl, ruthenium complex, X-ray structure.