Search results for "METHANE"
showing 10 items of 1763 documents
In-depth structural analysis of lanthanoid coordination networks based on a flexible tripodal zwitterionic isonicotinate ligand
2019
Crystallizing metal–organic frameworks (MOFs) has been studied using a tripodal pyridinecarboxylic acid derivative ligand and selected lanthanoid salts. The zwitterionic ligand, 1,1′,1′′-((2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene))tris(pyridin-1-ium-4-carboxylate) (TTTPC) introduced as a bromide salt, forms coordination networks in aqueous environments and under ambient conditions with neodymium bromide, trifluoromethanesulfonate (OTf) or acetate (OAc). Seven structures are elucidated in detail using single crystal X-ray crystallography. TTTPC NdBr3, TTTPC NdBr2OTf, TTTPC NdBr(OTf)2 and TTTPC Nd(OTf)3 are porous 3D networks with similar ligand–metal and ligand–anion interactions, b…
Lanthanide bis(trifluoromethylsulfonyl)amides vs. trifluoromethylsulfonates as catalysts for Friedel–Crafts acylations
2002
Abstract The use of catalytic amounts: 1 mol% or less of perfluoroalkyl lanthanide salts as homogeneous catalysts for Friedel–Crafts acylations in non-hazardous solvents is thereafter investigated. Lanthanide bis(trifluoromethylsulfonyl)amides are better catalysts than the triflate analogues towards the acetylation of activated aromatic rings.
A SIM-MOF: Three-Dimensional Organisation of Single-Ion Magnets with Anion-Exchange Capabilities
2014
The formation of a metal-organic framework (MOF) with nodes that have single-molecule magnet (SMM) behaviour has been achieved by using mononuclear lanthanoid analogues, also known as single-ion magnets (SIMs), which enormously simplifies the challenging issue of making SMM-MOFs. Here we present a rational design of a family of MOFs, [Ln(bipyNO)4](TfO)3⋅x solvent (Ln=Tb (1); Dy (2); Ho (3); Er (4); TfO=triflate), in which the lanthanoid centres have an square-antiprismatic coordination environment suitable for SIM behaviour. Magnetic measurements confirm the existence of slow magnetic relaxation typical of SMMs, which has been rationalised by means of a radial effective charge model. In add…
Effect of the remaining lanthanide catalysts on the hydrolytic and enzymatic degradation of poly-(ε-caprolactone)
2003
Poly-(e-caprolactone) is a biodegradable polymer, which can be used for both medical and environmental applications. Due to its multiple applications the synthesis of such a polymer has been attracting an increasing attention in the past few decades. In our work, the polymers were synthesised by bulk polymerisation, using different lanthanide halides as initiators. The lanthanide derivatives are known as very active catalysts in the ring-opening polymerisation of cyclic esters. Moreover, they are not toxic in comparison of catalysts, which are usually used for this synthesis. In this paper, the influence of the lanthanides on both the hydrolytic and enzymatic degradation of the PCL obtained…
Carbamoylmethylphosphinoxide derivatives based on the triphenylmethane skeleton. Synthesis and extraction properties.
2005
Two different strategies were used to synthesize tri(2-alkoxy-5-nitrophenyl)methanes 6a,b. The X-ray structures of 6a and its precursor 5 show the molecules in a conformation with a syn-orientation of the nitro and alkoxy groups. Hydrogenation and acylation by the appropriate active ester gave the corresponding tri-CMPO derivatives 4a,b. Their ability to complex lanthanide ions was studied by NMR spectroscopy and by nuclear magnetic relaxation dispersion and further characterized by quantum mechanical calculations. Extraction experiments from acidic solution to dichloromethane reveal a reasonable selectivity of Am(III) over Eu(III), but in contrast to similar tetra-CMPOs derivatives of cali…
Conformationally Mobile Wide Rim Carbamoylmethylphosphine Oxide (CMPO)-Calixarenes
1999
Six new calix[4]arene derivatives 2a–f have been synthesised, bearing CMPO-like functions (-NH–C(O)–CH2–P(O)Ph2) at their wide rim. They differ by their alkoxy groups at the narrow rim, comprising all possible combinations of methoxy and syn-propoxy groups including the conformationally mobile tetramethyl ether 2e and the tetrapropyl ether 2f fixed in the cone conformation. Their extraction behaviour for thorium(IV) and several lanthanides(III) from 1M HNO3 to dichloromethane has been studied and compared also to non cyclic calixarene analogues 6a–e. Surprisingly the best extraction results were found for the 1,2-dimethoxy-3,4-dipropoxy derivative 2c among the calixarenes and for the tetram…
A genetic link between synsedimentary tectonics-expelled fluids, microbial sulfate reduction and cone-in-cone structures
2018
14 pages; International audience; The late Jurassic (Tithonian) marlstones of the Boulonnais area (English Channel, France) contains diagenetic carbonate beds and nodules. Some nodules exhibit cone-in-cone structures on their lower face. We studied such nodules using various techniques of imaging and chemical (major and trace-elements) and isotopic analyses (Ccarb, Corg, O and S stable isotopes). We interpret the cone-in-cone to be the end product of carbonate-nodule formation during early diagenesis. The diagenetic carbonate precipitation was induced by microbial activity (bacteria and(?) archeae) fueled by upward-migrating fluids. Fluid expulsion was itself triggered by synsedimentary fau…
Coordination of expanded terpyridine ligands to cobalt
2013
Abstract The tridentate expanded terpyridine-like ligand N,N′-dimethyl-N,N′-dipyridin-2-yl-pyridin-2,6-diamine (ddpd) and [Co(H2O)6](BF4)2 give the high-spin complex mer-[Co(ddpd)2](BF4)2 with a tetragonally compressed CoN6 coordination geometry according to X-ray diffraction and SQUID measurements. UV–Vis–NIR spectra indicate a large ligand field splitting close to the high-spin/low-spin crossover point. Oxidation of the CoII complex to CoIII is achieved with silver triflate. The self exchange between high-spin CoII and low-spin CoIII is slow on the NMR time scale.
Mono-, bi- and polynuclear complexes of diphenylmethane with Cr, Co and Ru. Synthesis and investigation by 1H, 13C and 17O NMR
1995
Abstract Complexes of diphenylmethane (Ph 2 CH 2 ): Ph 2 CH 2 Cr(CO) 3 ( 1 ), Ph 2 CH 2 [Cr(CO) 3 ] 2 ( 2 ), Ph 2 CH 2 Co 4 (CO) 9 ( 3 ), Ph 2 CH 2 [Co 4 (CO) 9 ] 2 ( 4 ), Ph 2 CH 2 Cr(CO) 3 Co 4 (CO) 9 ( 5 ) and Ph 2 CH 2 Ru 6 C(CO) 14 ( 6 ) have been prepared and characterized by 1 H and 13 C-and 17 O-NMR spectroscopy. Strong shielding effects are caused by the metal valence electrons on the 1 H- and 13 C-NMR chemical shifts of aromatic protons and carbons in π-coordinated ring(s) diphenylmethane. Generally, the order of these shielding effects on the nuclei of the aromatic rings in 1 H-NMR was Co 4 (CO) 9 6 C(CO) 14 3 and in 13 C-NMR Co 4 (CO) 9 3 6 C(CO) 14 . In addition, aromatic solve…
C,N-chelated organotin(IV) trifluoromethanesulfonates: Synthesis, characterization and preliminary studies of its catalytic activity in the direct sy…
2012
Abstract C,N-chelated tri- and diorganotin(IV) halides react with 1 or 2 mol equiv of silver trifluoromethanesulfonate (triflate, AgOTf, OTf = OSO2CF3−) to give corresponding C,N-chelated organotin(IV) triflates. The triorganotin(IV) triflates of general formula LCNR2SnOTf (R = n-Bu (1), Ph (2)) are presumably more stable towards hydrolysis than the diorganotin(IV) triflates LCNRSn(OTf)2 (R = n-Bu (3), Ph (4)). All prepared organotin(IV) triflates bearing the LCN ligand (where LCN is 2-(N,N-dimethylaminomethyl)phenyl-) were characterized by multinuclear NMR spectroscopy and elemental analysis. In addition, the structure of 3 was determined by the X-ray diffraction analysis. The catalytic ac…