Formation of diphenylphosphanylbutadienyl complexes by insertion of two P-coordinated alkynylphosphanes into a PtbondC6F5 bond: detection of intermediate and reaction products

The reactions between cis-[M(C(6)F(5))(2)(PPh(2)CtriplebondCR)(2)] (M=Pt, Pd; R=Ph, tBu, Tol 2, 3) or cis-[Pt(C(6)F(5))(2)(PPh(2)CtriplebondCR)(PPh(2)CtriplebondCtBu)] (R=Ph 4, Tol 5) and cis-[Pt(C(6)F(5))(2)(thf)(2)] 1 have been investigated. Whereas [M](PPh(2)CtriplebondCtBu)(2) ([M]=cis-M(C(6)F(5))(2)) is inert towards 1, the analogous reactions starting from [M](PPh(2)CtriplebondCR)(2) or [Pt](PPh(2)CtriplebondCR)(PPh(2)CtriplebondCtBu) (R=Ph, Tol) afford unusual binuclear species [Pt(C(6)F(5))(S)mu-[C(R')dbondC(PPh(2))C(PPh(2))doublebondC(R)(C(6)F(5))]M(C(6)F(5))(2)] (R=R'=Ph, Tol, M=Pt 6 a,c, M=Pd 7 a,c; M=Pt, R'=tBu, R=Ph 8, Tol 9) containing a bis(diphenylphosphanyl)butadienyl bridging ligand formed by an unprecedented sequential insertion reaction of two P-coordinated PPh(2)CtriplebondCR ligands into a PtbondC(6)F(5) bond. Although in solution the presence of coordinated solvent S (S=(thf)(x)(H(2)O)(y)) in 6, 7 is suggested by NMR spectroscopy, X-ray diffraction analyses of different crystals of the mixed complex [Pt(C(6)F(5))mu-[C(tBu)doublebondC(PPh(2))C(PPh(2))doublebondC(Tol)(C(6)F(5))]Pt(C(6)F(5))(2)] 9 unequivocally establish that in the solid state the steric crowding of the new diphenylbutadienyl ligand formed stabilizes an unusual coordinatively unsaturated T-shaped 3-coordinated platinum(II) center. Structure determinations of the mononuclear precursors cis-[Pt(C(6)F(5))(2)(PPh(2)CtriplebondCR)(2)] (R=Ph, tBu, Tol) have been carried out to evaluate the factors affecting the insertion processes. The reactions of the platinum complexes 6 towards neutral ligands (L=CO, py, PPh(2)H, CNtBu) in a 1:1 molar ratio afford related diplatinum derivatives 10-13, whereas treatment with CNtBu (1:2 molar ratio) or 2,2'-bipy (1:1 molar ratio) results in the opening of the chelating ring to give cis,cis-[Pt(C(6)F(5))(L)(2)mu-[1-kappaC(1):2-kappaPP'-C(R)doublebondC(PPh(2))C(PPh(2))doublebondC(R)(C(6)F(5))]Pt(C(6)F(5))(2)] (14, 15). The unsaturated or solvento complexes are unstable in solution evolving firstly, through an unexpected formal 4-1 R (Ph, Tol) migration, to the intermediate diphosphanylbutadienyl isomer derivatives [Pt(C(6)F(5))(S)mu-[C(C(6)F(5))doublebondC(PPh(2))C(PPh(2))doublebondC(R)(2)]M(C(6)F(5))(2)] (16, 18) (X-ray, R=Ph, M=Pt) and, finally, to 1-pentafluorophenyl-2,3-bis(diphenylphosphanyl)naphthalene mononuclear complexes (17, 19) by annulation of a phenyl or tolyl group.     

The crystal and molecular structures of two bromo bis(N,N-dipropylthiocarbamoyl) sulfidocopper(I) complexes

The reaction of copper(I) bromide, CuBr, with the tetraalkylthiurammonosulfides R₄tms (R = ⁱPr, ⁿPr) affords the copper(I) complexes ⁱPr₄tmsCuBr (I) (C₁₄H₂₈BrCuN₂S₂, orthorhombic, Pna2₁, Z = 4, a = 12.487(2), b = 12.699(2), c = 12.742(2) Å) and ⁿPr₄tmsCuBr (II) (C₁₄H₂₈BrCuN₂S₃, monoclinic, P2₁/n, Z = 4, a = 9.092(5), b = 23.408(11), c = 10.082(7) Å, = 104.90(5)°), which exist in the solid as monomeric units featuring three-coordinate copper(I). The ligands are bidentate and coordination is completed by the bromine atoms. The configurations of the six-membered metal-ligand ring in (I) and (II) are more severely distorted than the previously reported structurally related complexes of ethyl series. The crystal structural studies are complemented and confirmed by IR and ¹H-NMR spectroscopies, as well as room temperature, magnetic, solution conductivity, and molecular weight studies.     

Magneto-structural characterization of Cu4(prz)2(L)2Cl4 ·CH3CH2OH (LH=1,1-di-2-pyridyl-1-ethoxi methanol,przH=pyrazole)

The title compound, Cu₂C₁₇H₁₆O_2.5Cl₂, is a copper(II) complex, in which each dimeric unit has two copper atoms bridged by a pyrazolato ligand, a di(2-pyridyl)]methane ligand, and an oxygen atom from the modified methylene group that links the two pyridine rings (O-C-O-CH₂CH₃). The complex crystallizes in the monoclinic groupP2₁/n,a=7.7330(1),b=19.589(6),c=13.123(2)Å,=95.020(0)°,V=1980.3(7)ų,Z=4,F _w=514.3,D _Do =1.725 g cm^–3(MoK)=0.71073 Å,F(000)=1032,=2.44 mm^–1, R=0.044 for 2209 observed reflections,Rw=0.047,s=0.086. Each dimer is linked to the next unit by long chlorine bonds (Cu(2)-Cl(1)=2.846(2)Å). These tetrameric units form zigzagged chains through copperchlorine bonds of 3.380(2)Å. The copper(II) complex presents antiferromagnetic behavior withT _m=161 K.     

Structural investigation of 1-amino-2,4,6-trinitrobenzenes in the solid state and in solution

The crystal structure of 1-pyrrolidino-2,4,6-trinitrobenzene3, 1-morpholino-2,4,6-trinitrobenzene4 and 1-piperidino-2,4,6-trinitrobenzene5 have been determined by single-crystal X-ray diffraction data and the structure in solution was investigated by UV-visible spectrophotometry and¹³C nmr. The three compounds are monoclinic, space groupP2_i/n. Unit cell dimensions area=6.6660(1),b=8.612(1),c=20.696(3) Å, β=90.73(1)^o, andD _c =1.58 g cm^?3 for compound3;a=7.090(2),b=21.493(9),c=8.298(3) Å, β=101.27(1)^o, andD _c 1.60 g cm^?3 for compound4 anda=10.426(1),b=10.038(1),c=12.291(1) Å, β=90.04(1)^o withD _c =1.53 g cm^?3 for compound5 forZ=4. In the solid state, differences regarding the planarity of the aromatic ring in the three substrates were found. Rotation of theortho-nitro groups and of the amino group out of the aromatic plane was observed both in the solid state and in the solution. Greater coplanarity of the two rings was found in3 than in4 and5.     

Proangiogenic Effect of Affinin and an Ethanolic Extract from Heliopsis longipes Roots: Ex Vivo and In Vivo Evidence

Angiogenesis, the formation of new blood vessels, underlies tissue development and repair. Some medicinal plant-derived compounds can modulate the angiogenic response. Heliopsis longipes, a Mexican medicinal plant, is widely used because of its effects on pain and inflammation. The main bioactive phytochemicals from H. longipes roots are alkamides, where affinin is the most abundant. Scientific studies show various medical effects of organic extracts of H. longipes roots and affinin that share some molecular pathways with the angiogenesis process, with the vasodilation mechanism of action being the most recent. This study investigates whether pure affinin and the ethanolic extract from Heliopsis longipes roots (HLEE) promote angiogenesis. Using the aortic ring rat assay (ex vivo method) and the direct in vivo angiogenesis assay, where angioreactors were implanted in CD1 female mice, showed that affinin and the HLEE increased vascular growth in a dose-dependent manner in both bioassays. This is the first study showing the proangiogenic effect of H. longipes. Further studies should focus on the mechanism of action and its possible therapeutic use in diseases characterized by insufficient angiogenesis.     

A Synergistic Effect of Select Organotin Compounds and Ionic Surfactants on Liposome Membranes

Organometallic compounds and surfactants constitute a potential threat to the environment. For that reason we have embarked on a study of their joint action on membranes. Model lecithin liposome membranes were modified with the cationic surfactant trimethyldodecylammonium bromide or the anionic surfactant sodium dodecylsulfonate, and the effect of tripropyltin chloride on the process of calcium (Ca²⁺) and praseodymium (Pr³⁺) desorption from the liposome membrane was studied. Kinetic constants for the process of Ca²⁺ ion desorption from lecithin liposome membranes were determined using the radiotracer method. The percentage of Pr³⁺ ion desorption from liposome membranes was measured by the ¹H NMR method. Trimethyltin, triethyltin and tripropyltin alone caused increased Ca²⁺ and Pr³⁺ desorption from liposome membranes with increasing concentration of the compounds and alkyl chain length. For both the processes studied, a cationic surfactant brought about a lower effectiveness of tripropyltin and an anionic surfactant resulted in a higher effectiveness. The effect observed can be explained by changes in the surface charge of the membrane, induced by the surfactant modifiers and by the concomitant change in the partition coefficient of the organotin. The results obtained indicate a protective or harmful joint action of the surfactants used with tripropyltin on membranes. © 1997 John Wiley & Sons, Ltd.     

Resolution of Racemic 1,2-Dibromohexafluoropropane through Halogen-Bonded Supramolecular Helices

Halogen bonds , attractive intermolecular interactions between perfluoroalkyl bromides and bromide ions, are present in cocrystals of (−)-sparteinium hydrobromide ( 1 ) and (S)-1,2-dibromohexafluoropropane ( 2 ; shown schematically), and result in enantiopure and infinite supramolecular helices. The perfluorocarbon–hydrocarbon self-assembly allows the resolution of racemic 2 .     

Anti-Inflammatory and Immunoregulatory Action of Sesquiterpene Lactones

Sesquiterpene lactones (SL), characterized by their high prevalence in the Asteraceae family, are one of the major groups of secondary metabolites found in plants. Researchers from distinct research fields, including pharmacology, medicine, and agriculture, are interested in their biological potential. With new SL discovered in the last years, new biological activities have been tested, different action mechanisms (synergistic and/or antagonistic effects), as well as molecular structure–activity relationships described. The review identifies the main sesquiterpene lactones with interconnections between immune responses and anti-inflammatory actions, within different cellular models as well in in vivo studies. Bioaccessibility and bioavailability, as well as molecular structure–activity relationships are addressed. Additionally, plant metabolic engineering, and the impact of sesquiterpene lactone extraction methodologies are presented, with the perspective of biological activity enhancement. Sesquiterpene lactones derivatives are also addressed. This review summarizes the current knowledge regarding the therapeutic potential of sesquiterpene lactones within immune and inflammatory activities, highlighting trends and opportunities for their pharmaceutical/clinical use.     

A barium perchlorate complex with a lateral macrobicycle derived from 1,10‐di­aza‐15‐crown‐5 containing a phenol Schiff base spacer

In the crystal structure of (acetonitrile‐κN)[13‐methyl‐39‐oxido‐1,17,25‐tri­aza‐9‐azonia‐28,31,36‐trioxapentacyclo[23.8.5.1^11,15.0^3,8.0^18,23]nonatriaconta‐3,5,7,9,11,13,15(39),16,18,20,22‐un­decaene‐κ⁷N¹,N¹⁷,N²⁵,O²⁸,O³¹,O³⁶,O³⁹](perchlorato‐κ²O,O′)barium(II) perchlorate acetonitrile hemisolvate, [Ba(ClO₄)(C₂H₃N)(C₃₃H₄₀N₄O₄)]ClO₄·0.5CH₃CN, the barium(II) cation is asymmetrically situated in the macrobicyclic cavity and is bound to seven of the eight heteroatoms of the macrobicyclic ligand, to the N atom of an aceto­nitrile mol­ecule and to two O atoms of one perchlorate group. The azonia N atom is not coordinated to the barium(II) cation and is involved in an intramolecular hydrogen‐bonding interaction with the oxido O atom.