Search results for "Derivative"
showing 10 items of 1074 documents
Unprecedented reactivity of a Schiff base ligand in the co-ordination sphere of copper(I) complex towards β-diketones. Synthesis and X-ray characteri…
2002
International audience; The reactions of the copper(I) derivative [CuL(THF)(CH3CN)]PF6 (1), in which L is the di-imine/pyridine ligand 2,6-bis[1-(2,6-diisopropylphenylimino)ethyl]pyridine, with different β-diketones (2,4-pentanedione (acacH), 1,3-diphenyl-1,3-propanedione (dbm)) yielded the new Cu(I) salt [CuL′2]PF6 (2) (L′: 2-[acetyl]-6-[1-(2,6-diisopropylphenylimino)ethyl]pyridine). These reactions of β-diketones with a di-imine/pyridine ligand co-ordinated to a Cu(I) centre constitute the first example of a partial hydrolysis of such a Schiff base within the inner sphere of a Cu centre. Compound 2·acaH has been characterised by X-ray crystallography. © 2002 Elsevier Science B.V. All righ…
(S)-2-[(2-Hydroxybenzyl)azaniumyl]-4-(methylsulfanyl)butanoate
2011
The zwitterionic title compound, C12H17NO3S, is a reduced Schiff base derived from (S)-N-(2-hydroxybenzylidene)methionine. An intramolecular interaction between the N—H and carboxylate groups forms a roughly planar (r.m.s. deviation = 0.1405 Å) five-membered ring containing the H(N), N, Cα, C(carboxylate) and O atoms in a pentagonal conformation. In the crystal, a supramolecular triangle-shaped motif is generated by molecules held together by O—H...O and N—H...O hydrogen bonds.
2-Amino-2-methyl-1,3-propanediol (ampdH2) as ligand backbone for the synthesis of cobalt complexes: Mononuclear Co(II), binuclear Co(II,III) and hexa…
2013
Abstract Three cobalt complexes have been synthesized using 2-amino-2-methyl-1,3-propanediol (ampdH2) and its Schiff base derivative ligands and structurally characterized. The three complexes 1, 2 and 3 are very different and consist of mononuclear Co(II), mixed-valence binuclear Co(II,III) and mixed-valence hexanuclear Co(II,III) complexes respectively. The properties of the coordinated donor atoms of the ligand play the predominant role in stabilizing the oxidation states of the cobalt centers. The presence of intermolecular hydrogen bonds in 1 via non-coordinating perchlorate ions lead to the formation of a 1D-Chain network while a sheet-like 2D network was observed in 3.
Magnetic and catalytic properties of a new copper(II)–Schiff base 2D coordination polymer formed by connected helical chains
2011
Abstract A dicyanamide bridged 2D polynuclear complex of copper(II) having molecular formula [Cu2(L)(μ1,5-dca)2]n (1) has been synthesized using the Schiff base ligand N,N′-bis(salicylidene)-1,3-diaminopentane, (H2L) and sodium dicyanamide (dca). The complex presents a 2D hexagonal structure formed by 1,5-dca singly bridged helical chains connected through double 1,5-dca bridges. The chelating characteristics of the H2L Schiff base ligand results in the formation of copper(II) dimer with a double phenoxo bridge presenting a very strong antiferromagnetic coupling in the copper(II) derivative (1) (J = −510 cm−1). The dimeric asymmetric unit of 1 is very similar to the active site of the catec…
Poisson-Nijenhuis structures and the Vinogradov bracket
1994
We express the compatibility conditions that a Poisson bivector and a Nijenhuis tensor must fulfil in order to be a Poisson-Nijenhuis structure by means of a graded Lie bracket. This bracket is a generalization of Schouten and Frolicher-Nijenhuis graded Lie brackets defined on multivector fields and on vector valued differential forms respectively.
Steady-state radiation heat transfer problem
1996
In Section 8.2, we shall see that the steady-state radiative heat transfer problem can be transformed to minimization of a smooth nonquadratic functional J over a convex and closed subset of a Banach space V. To this end we firstly shortly recall some basic definitions concerning differentiability of J, because these sometimes differ in the literature.
Marine inspired antiplasmodial thiazinoquinones: synthesis, computational studies and electrochemical assays
2015
In the search for new antimalarials, we used the quinone scaffold of marine secondary metabolites as a chemical starting point to synthesize new thiazinoquinone compounds. Most of synthetic derivatives have shown a significant pharmacological activity and some structural requirements, critical for both the antiplasmodial effect and cytotoxicity, have been evidenced. The redox properties of the prepared compounds have been investigated by computational studies and electrochemical assays, which indicated that a higher antiplasmodial activity of some thiazinoquinones is related to their greater ability to form the semiquinone species and strongly interact with free Fe(III)-protoporphyrin IX.
SINGLE FACTOR STOCHASTIC MODELS WITH SEASONALITY APPLIED TO UNDERLYING WEATHER DERIVATIVES VARIABLES
2003
This paper estimates single factor stochastic models describing daily air temperature behaviour. We modify classical financial models to reflect temperature seasonality and fit them to a time series representing temperatures in Spain. The estimated models are used in Montecarlo simulations to obtain heating and cooling degree-days, which are used as an underlying reference in weather derivatives. The final goal of this work is to obtain an insight into weather derivative valuation, and so making it easier to manage economic activity risks closely related to temperature (i.e. oil, gas and electricity prices and volumes). En este trabajo se estiman modelos estocásticos unifactoriales que desc…
Novel bioactive bromopyrrole alkaloids from the Mediterranean sponge Axinella verrucosa
2005
The Mediterranean sponge Axinella verrucosa has been investigated for its alkaloid composition and has been found to produce a complex mixture of bromopyrrole alkaloids. Along with the previously isolated compounds 5-18, four novel alkaloids of this class, compounds 1-4, have been isolated, and their structures established through spectroscopic methods. Compounds 1-4 were found to display neuroprotective activity against the agonists serotonin and glutamate in vitro.
Chemical composition and herbicidal activity of the essential oil from a Cistus ladanifer population from Spain
2012
[EN] The essential oil composition of Cistus ladanifer grown in central Spain was analysed by gas chromatography and gas chromatography/mass spectrometry, revealing it to be rich in oxygenated compounds, with trans-pinocarveol (20.00%), bornyl acetate (7.03%) and terpinen-4-ol (6.37%) as the main monoterpene compounds. Viridiflorol (13.59%) and ledol (4.36%) were the main constituents of the oxygenated sesquiterpene fraction. Large amounts of-pinene (4.70%) were found in the hydrocarbonated fractions. To study its possible use as a natural herbicide, the oil was tested invitro against Amaranthus hybridus, Portulaca oleracea, Chenopodium album, Conyza canadensis and Parietaria judaica, compl…