Search results for "Cyclam"
showing 10 items of 72 documents
Triterpene Saponins from Cyclamen persicum
2010
A new triterpene saponin 3- O-β-D-glucopyranosyl-(1→4)-α-L-arabinopyranosyl-16α-hydroxy-13β,28-epoxy-oleanan-30-al (1), along with four known triterpene glycosides (2-5) were isolated from Cyclamen persicum. Their structures were characterized by a combination of 1D- and 2D-NMR (1H-1H COSY, TOCSY, NOESY, HSQC, and HMBC) and MS spectrocopic data. The cytotoxicity of compounds 2 and 4 was evaluated using two human colon cancer cell lines HT-29 and HCT 116.
A novel two-dimensional honeycomb-like bimetallic iron(iii)–nickel(ii) cyanide-bridged magnetic material [Ni(cyclam)]3[Fe(CN)6]2·nH2O (cyclam = 1,4,8…
1999
The 2D honeycomb-like layered iron(iii)–nickel(ii) cyanidebridged complex [Ni(cyclam)]3[Fe(CN)6]2·nH2O exhibits ferromagnetic intralayer and antiferromagnetic interlayer interactions; above 3 K the magnetic properties are typical of a metamagnet with Hc = 5000 G, whereas below 3 K a canted structure is formed, leading to a long range ferromagnetic ordering. Lloret Pastor, Francisco, Francisco.Lloret@uv.es
Cyano-Bridged Bimetallic Assemblies from Hexacyanometalate, [M(CN)6]3- (M = MnIII and FeIII), and [M(N4-macrocycle)]2+ (M = FeIII, NiII and ZnII) Bui…
2001
Reactions between [M(N4-macrocycle)]2+ (M = ZnII and NiII; macrocycle ligands are either CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane or cyclam = 1,4, 8, 11-tetrazaazaciclotetradecane) and [M(CN)6]3- (M = FeIII and MnIII) give rise to cyano-bridged assemblies with 1D linear chain and 2D honeycomblike structures. The magnetic measurements on the 1D linear chain complex [Fe(cyclam)][Fe(CN)6]·6H2O 1 points out its metamagnetic behavior, where the ferromagnetic interaction operates within the chain and the antiferromagnetic one between chains. The Neel temperature, TN, is 5.5 K and the critical field at 2 K is 1 T. The unexpected ferromagnetic intrachain interaction can…
Remarkable Inertness of Copper(II) Chelates of Cyclen-Based Macrobicycles with Two trans-N-Acetate Arms
2013
Two cross-bridged cyclen-based macrocycles with two trans-N-acetic acid arms, one having a dibenzofuran (DBF) moiety as the bridge, H2L1, and the other a diphenyl ether (DPE) one, H2L2, were synthesized. Both compounds behave as "proton sponges." The thermodynamic stability constants for the Cu(2+), Zn(2+), Al(3+), and Ga(3+) complexes of both compounds were determined. They exhibit an excellent thermodynamic selectivity for copper(II), ensuring that metal ions largely present in the human body do not interfere with the copper(II) chelates. All complexes are very slow to form, and [CuL2] and [CuL1] are extremely inert to demetallate, especially [CuL2]. The acid-assisted dissociation of [CuL…
Plerixafor is effective and safe for stem cell mobilization in heavily pretreated germ cell tumor patients.
2010
Up to 10% of germ cell tumor patients require salvage high-dose chemotherapy with stem cell support, achieving cure rates in the range of 10-60%. Stem cell mobilization may be difficult in these patients because of multiple lines of treatment known to seriously hamper stem cell recovery. Plerixafor significantly enhances the success of the CD34+ cell harvest, even in cases where prior mobilization attempts have failed. Six germ cell tumor patients provided informed consent and were included in the compassionate use program. All patients were heavily pretreated, with a median of 3.5 prior lines of therapy. All failed prior mobilization with G-CSF in combination with chemotherapy. Five patien…
Fusarium wilt of cyclamen : early detection and biocontrol
2016
Fusarium wilt of cyclamen is one of the most damaging diseases of cyclamen. The causal agent, Fusarium oxysporum f. sp. cyclaminis, is a soil-borne fungus. Losses can reach more than 50 % of the production. Several methods of control are available, but none of them offer an efficient and environmentally friendly solution. In this context, a project was developed in collaboration with the French institute of horticulture, Astredhor, which represents the producers, the INRA of Dijon, for its expertise on F. oxysporum and the company Agrene for its expertise in biological control. The project has two goals: i) design a molecular marker specific of Fusarium oxysporum f. sp. cyclaminis allowing …
A molecular approach to remove lead from drinking water
2005
Abstract Corrosion of lead-containing plumbings is responsible for significant contamination of tap water, which can reach several hundreds of micrograms per liter. According to a decision of the European Council applicable in 2013, the maximal lead level in tap water should not exceed 10 μg l −1 . A new concept has been explored that relies on solid-phase extraction by covalent attachment of a lead-selective macrocyclic sequestering agent onto the surface of silica gel. An N -carbamoylmethyl substituted 1,4,8,11-tetraazacyclotetradecane (cyclam) derivative was shown to exhibit favorable protonation properties together with an almost 10 6 -fold selectivity for lead over calcium. Structural …
Synthesis, characterization and X-ray crystal structures of cyclam derivatives. Part VI. Proton binding studies of a pyridine-strapped 5,12-dioxocycl…
2005
The 14-membered cyclic diamide 1,4,8,11-tetraazacyclotetradecane-5,12-dione (5,12-dioxocyclam) can be considered as a trans-autodiprotected tetraazamacrocycle and provides a convenient starting material for the preparation of macrobicyclic receptors. As an example, the secondary amine nitrogen atoms located at the 1 and 8 positions were cross-bridged with a 1,3-pyridyl strap, affording the constrained ansa-dioxocyclam ligand 1,9,12,18,22-pentaazatricyclo[7.6.6.13,7]docosa-3,5,7(22)-triene-13,19-dione (L1). The proton binding properties of this cage-type compound, which possesses a hemispherical cavity, were fully investigated by spectroscopic (IR, NMR, UV, MALDI-TOF MS), quantum chemical, a…
Synthesis of Macropolycyclic Ligands Based on Tetraazacycloalkanes
1998
A versatile synthesis of spherical macrobicyclic and cylindrical macrotricyclic ligands is described using 1,4,8,11-tetraazacyclotetradecane (cyclam), 1,4,7,10-tetraazacyclododecane (cyclen), or dioxo macrocycles as precursors. Macrobicycles have been obtained by allowing cyclam, cyclen, or 5,12-dioxocyclam (1,4,8,11-tetraazacyclotetradecane-5,12-dione) to react with a bis-electrophilic spacer under high dilution conditions. A surprising selectivity has been observed for 2,6-dioxocyclen (1,4,7,10-tetraazacyclododecane-2,6-dione), which yields only macrotricycles under the same reaction conditions. Molecular modelling studies have been carried out to investigate the selectivity of the reacti…
Multiarm cyclam-grafted mesoporous silica: a strategy to improve the chemical stability of silica materials functionalized with amine ligands
2009
We have explored in this work the stability and the reactivity of multiarm cyclam-grafted mesoporous silica samples in aqueous solution. A series of hybrid materials have been prepared by grafting silylated cyclam molecules bearing one, two, or four silyl groups onto both amorphous silica gel (K60) and ordered mesoporous silica (SBA15). Under these conditions, cyclam moieties are attached to the silica walls via one, two, or four arms. Various physicochemical techniques have been applied to characterize the functionalized solids (elemental analysis, 1H-29Si and 1H-13C CPMAS NMR, and N2 adsorption-desorption isotherms). The interest in two and four arms for improving the chemical stability i…