Chemistry of 2-(phenylazo)pyridine complexes of osmium: synthesis, characterization and reactivities

Reaction of 2-(phenylazo)pyridine (pap) with [Os(PPh3)3Br2] afforded a mixed ligand complex of the type [Os(PPh3)2(pap)Br2]. The structure of this complex was determined by X-ray crystallography. The PPh3 ligands are trans and the bromides are in cis positions. The pap ligand is coordinated to osmium as a bidentate N,N-donor forming a five-membered chelate ring. The complex is diamagnetic (low-spin d6, S=0) and in dichloromethane solution shows intense MLCT transitions in the visible region. The two bromides were replaced from the coordination sphere of [Os(PPh3)2(pap)Br2] under mild conditions by a series of anionic ligands L (where L=quinolin-8-olate (q), picolinate (pic), oxalate (Hox), 1-nitroso-2-naphtholate (nn) and acetyl acetonate (acac)) to afford complexes of the type [Os(PPh3)2(pap)(L)]+, which were isolated and characterized as the perchlorate salt. The structure of the [Os(PPh3)2(pap)(acac)]ClO4 complex was determined by X-ray crystallography. The PPh3 ligands occupy trans positions and the acetylacetonate anion is coordinated to osmium as a bidentate O,O-donor forming a six-membered chelate ring. The [Os(PPh3)2(pap)(L)]+ complexes are diamagnetic and show multiple MLCT transitions in the visible region. [Os(PPh3)2(pap)Br2] shows an osmium(II)-osmium(III) oxidation at 0.49 V versus SCE. The same oxidation is displayed by the [Os(PPh3)2(pap)(L)]+ complexes within 0.69 to 0.96 V versus SCE. Two successive one-electron reductions of the coordinated pap ligand are also observed in all the complexes below -0.90 V versus SCE

Chemistry of ruthenium with some dioxime ligands. Syntheses, structures and reactivities

Reaction of two dioxime ligands, viz. dimethylglyoxime (H2dmg) and diphenylglyoxime (H2dpg), (abbreviated in general as H2L, where H stands for the oxime protons) with [Ru(PPh3)3Cl2] in 1¦1 mole ratio affords complexes of type [Ru(PPh3)2(H2L)Cl2]. Structure of the [Ru(PPh3)2(H2dpg)Cl2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is N2P2Cl2 with the two PPh3 ligands in trans and the two chlorides in cis positions. Reaction of the dioxime ligands with [Ru(PPh3)3Cl2] in 2¦1 mole ratio in the presence of a base affords complexes of type [Ru(PPh3)2(HL)2]. Structure of the [Ru(PPh3)2(Hdmg)2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is N4P2 with the two PPh3 ligands in trans positions. Reaction of the [Ru(PPh3)2(H2dpg)Cl2] complex with a group of bidentate acidic ligands, viz. picolinic acid (Hpic), quinolin-8-ol (Hq) and 1-nitroso-2-naphthol (Hnn), (abbreviated in general as HL′, where H stands for the acidic proton) in the presence of a base affords complexes of type [Ru(PPh3)2(H2dpg)(L′)]+ isolated as perchlorate salts. All the complexes are diamagnetic (low-spin d6, S=0) and in dichloromethane solution show several intense MLCT transitions in the visible region. Cyclic voltammetry on all the complexes shows a reversible ruthenium(II)-ruthenium(III) oxidation within 0.36-0.98 V versus SCE followed by a quasi-reversible ruthenium(III)-ruthenium(IV) oxidation within 0.94-1.60 V versus SCE

A family of mixed ligand complexes of Ru<SUP>II</SUP>-L [L=N-aryl-pyridine-2-aldimine], their reactions, isolation and characterization. X-ray crystal structure of [Ru(pic)(L<SUP>1</SUP>)<SUB>2</SUB>][ClO<SUB>4</SUB>]. CH<SUB>2</SUB>Cl<SUB>2</SUB> [pic= 2-picolinate ion]

Synthesis of the tris-chelated complexes [Ru(L)n(L3)3-n]2+ (L=N-aryl-pyridine-2-aldimine, L3=2-(m-tolylazo)pyridine) based on silver(I) assisted trans-metallation is described. The complexes, [Ru(L)3]2+ and [Ru(L)(L3)2]2+ afford [Ru(pic)(L)2]+ and [Ru(pic)(L3)2]+ (pic= 2-picolinate ion) respectively, on hydrolysis and subsequent oxidation. When RuCl2(L)2 was reacted with two moles of [Ag(L3)2]+, a pink complex of composition [Ru(L)(L3)(L4)]+ [L4=N-aryl-2-picolinamide] was isolated along with the expected brown complex, [Ru(L3)(L)2]2+. Initial oxidation of the metal ion favours L&#8594;L4 conversion. The complexes have been characterized using spectroscopy and X-ray crystallography. The X-ray structure of [Ru(pic) (L1)2]ClO4.CH2Cl2 is reported. The metal oxidation as well as ligand reductions for the complexes have been studied voltammetrically in acetonitrile using platinum as the working electrode. It has been observed that the oxidation of the transformed complexes, viz. [Ru(pic) (L)2]+, [Ru(pic)(L3)2]+ and [Ru(L)(L3)(L4)]+ occur at lower potentials as compared to their parent [Ru(L)n(L3)3-n]2+ complexes. All the complexes show metal-to-ligand charge transfer transitions in the visible range and absorption energies linearly correlate with the differences between the metal oxidation and the first ligand reduction potentials

Synthesis, structure and electrochemical properties of tris-picolinate complexes of rhodium and iridium

Reaction of picolinic acid (Hpic) with rhodium trichloride or iridium trichloride affords tris-picolinate complexes of the type [M(pic)3] (M = Rh, Ir). The crystal structures of both complexes have been determined by X-ray diffraction. In both complexes, the picolinate ligands are coordinated to the metal center as bidentate N,O-donors forming five-membered chelate rings. There is one molecule of water of crystallization per molecule of each [M(pic)3] complex. The water molecule is hydrogen bonded to the carboxylate fragments of two adjacent [M(pic)3] molecules and thus acts as a bridge between the individual complex molecules. The complexes are diamagnetic (low-spin d6, S = 0) and show intense MLCT transitions in the visible region. Cyclic voltammetry on the [M(pic)3] complexes shows a M(III)-M(IV) oxidation near 1.0 V versus SCE and a ligand-centered reductive response near -1.0 V versus SCE

Monovalent copper complexes of N-aryl-pyridine-2-aldimine. Synthesis, characterization and structure

A direct synthetic route, based on silver(I) assisted metal exchange reaction, to cationic bis-ligand complexes of copper(I) involving N-aryl-pyridine-2-aldimines (L, 1) has been studied. These complexes are obtained as their perchlorates, [Cu(L)2]ClO4 (2). They have been characterized with the help of spectroscopy and X-ray crystallography. The X-ray structure of [Cu(L2)2]ClO4, where L2 is N-p-tolyl-pyridine-2-aldimine is reported. There are two crystallographically independent molecules in the asymmetric unit. The ligand L2 coordinates in a bidentate manner providing a highly distorted tetrahedral geometry about copper. The complexes show highly resolved symmetrical 1H NMR spectra. Intense MLCT absorptions are observed in the visible range. In methanol the CuL22+/CuL2+ couple has E&#189; ca, 0.35 V vs SCE at 298 K. The moderately high positive potential is brought about by the distortion in the geometry of CuL22+

Chemistry of some ruthenium phenolates: synthesis, structure and redox properties

Reaction of three phenolate ligands, viz. 2,4,6-tribromophenol (HL1, where H stands for the phenolic proton), 2-nitrophenol (HL2) and 2,4,6-trinitrophenol (HL3O), with [Ru(PPh3)3Cl2] in a 2&#166;1 molar ratio in the presence of a base gives complexes of type [Ru(PPh3)2(L)2] (L=L1, L2 and L3). The 2,4,6-tribromophenolate ligand (L1) binds to ruthenium as a bidentate O,Br-donor, while the 2-nitrophenolate ligand (L2) acts as a bidentate O,O-donor. 2,4,6-Trinitrophenol (HL3O) undergoes oxygen loss from one nitro group at the ortho position and coordinates to ruthenium in the 2-nitroso-4,6-dinitrophenolate (L3) form through the nitroso nitrogen and phenolate oxygen. The structures of the [Ru(PPh3)2(L1)2] and [Ru(PPh3)2(L3)2] complexes have been solved by X-ray crystallography. In [Ru(PPh3)2(L1)2] the coordination sphere around ruthenium is O2P2Br2 with a trans-cis-cis disposition of the three sets of donor atoms, respectively. In [Ru(PPh3)2(L3)2] ruthenium has a N2O2P2 coordination sphere with a cis-cis-trans arrangement of the three sets of donor atoms, respectively. The [Ru(PPh3)2(L)2] complexes are diamagnetic (low-spin d6, S=0) and in acetonitrile solution show intense MLCT transitions in the visible region. Cyclic voltammetry on the [Ru(PPh3)2(L)2] complexes shows a reversible ruthenium(II)-ruthenium(III) oxidation within 0.63-0.71 V versus SCE followed by an irreversible ruthenium(III)-ruthenium(IV) oxidation near 1.5 V versus SCE

Chemistry of ruthenium with some phenolic ligands: synthesis, structure and redox properties

Reaction of three phenolate ligands, viz. salicylaldehyde (HL1), 2-hydroxyacetophenone (HL2) and 2-hydroxynaphthylaldehyde (HL3), (abbreviated in general as HL, where H stands for the phenolic proton) with [Ru(PPh3)3Cl2] in 1&#166;1 mole ratio gives complexes of the type[Ru(PPh3)2(L)Cl2]. The structure of the [Ru(PPh3)2(L2)Cl2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium isO2P2Cl2 with a cis-trans-cis geometry, respectively. The [Ru(PPh3)2(L)Cl2] complexes are one-electron paramagnetic (low-spin d5, S=&#189;) and show rhombic ESR spectra in 1&#166;1 dichloromethane-toluene solution at 77 K. In dichloromethane solution the [Ru(PPh3)2(L)Cl2] complexes show several intense LMCT transitions in the visible region. Reaction between the phenolic ligands and [Ru(PPh3)3Cl2] in 2&#166;1 mole ratio in the presence of a base affords the [Ru(PPh3)2(L)2] complexes in two isomeric forms. 1H NMR spectra of one isomer shows that it does not have any C2 symmetry and has the cis-cis-cis disposition of the three sets of donor atoms. 1H NMR spectra of the other isomer shows that it has C2 symmetry. The structure of the isomer of the [Ru(PPh3)2(L1)2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is O4P2 with a cis-trans-cis disposition of the carbonylic oxygens, phenolate oxygens and phosphorus atoms, respectively. The [Ru(PPh3)2(L)2] complexes are diamagnetic (low-spin d6, S=O) and show intense MLCT transitions in the visible region. Cyclic voltammetry on the [Ru(PPh3)2(L)Cl2] complexes shows a ruthenium(III)---ruthenium(II) reduction near -0.3 V versus SCE and a ruthenium(III)---ruthenium(IV) oxidation in the range 1.08-1.24 V versus SCE. Cyclic voltammetry on both isomers of the [Ru(PPh3)2(L)2] complexes shows a ruthenium(II)---ruthenium(III) oxidation within 0.09-0.41 V versus SCE, followed by a ruthenium(III)-ruthenium(IV) oxidation within 1.31-1.52 V versus SCE

The role of nitric oxide in the outgrowth of trophoblast cells on human umbilical vein endothelial cells

AbstractObjectiveEmbryo implantation is a complex process that requires coordinated trophoblast–endometrial interactions. Previous studies demonstrated that the identification of nitric oxide synthase (NOS) in trophoblast cells and the remodeling of the implantation process by nitric oxide (NO) support the important role of NO during implantation. However, the role of NO in trophoblast–endometrial interactions is unclear and is therefore examined in this study.Materials and methodsWe cocultured BeWo trophoblast spheroids with human umbilical vein endothelial cell (HUVEC) monolayers to mimic the trophoblast–endometrial interaction. Nω-Nitro-l-arginine methyl ester hydrochloride (l-NAME), a competitive inhibitor of NOS, and sodium nitroprusside (SNP), an NO donor, were used to test the role of NO in the trophoblast–endometrial interaction.Resultsl-NAME diminished spheroid expansion on HUVEC monolayers in a concentration-dependent manner (p < 0.05). However, trophoblast spreading on HUVEC-free culture surfaces was unaffected by l-NAME treatment (p > 0.05). Significant suppression of spheroid expansion was found at the higher dose (1mM) of SNP (p < 0.05).ConclusionNO may be needed in the process of implantation, and an adequate but not overly NO-containing environment might be an important factor for successful implantation. This finding is worthy of further investigation

Роль органів державної влади та місцевого самоврядування в процесі реалізації прав людини і громадянина на одержання інформації

Автор досліджує роль органів державної влади та місцевого самоврядування в процесі реалізації прав людини і громадянина на одержання інформації При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/36646Автор исследует роль органов государственной власти и местного самоуправления в процессе реализации прав человека и гражданина на получение информации При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/36646The author explores the role of state and local authorities in the implementation of human and civil rights to information When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3664