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The preparation and characterization of a new family of dicopper(I) complexes containing Schiff-base ligands containing two tridentate binding sites linked by a xylyl spacer revealed the complexes to react very rapidly with [O.sub.2] to generate metastable [[[Cu.sup.III.sub.2][([mu]-O).sub.2](L)].sup.2} species.

A satellite-selective 1D-TOCSY method is developed for measuring long-range heteronuclear coupling constants between proton and proton bearing carbons. The comparison of two 1D-TOCSY spectra generated by selective inversion of each [super 13]C satellite of a certain proton signal, Hi, has helped in measuring the long-range heteronuclear couplings between protons of the same spin system as Hi and the carbon bonded to Hi.

The mechanism of highly enantioselective electrophilic amination and Michael addition of cyclic [beta]-ketoesters induced by lanthanides and (S,S)ip-pybox was studied. Intermediates based on simultaneous coordination of the lanthanide to both (S,S)-ip-box and [beta]-ketoester were detected by ESI mass spectrometry and NMR experiments.

Nitrogen containing 15-membered triacetylenic macrocycles known as 1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3,8,13-triynes and enediynic macrocycles called 1,6,11-tris(arylsulfonyl)-1,6,11-triazacyclopentadeca-3-ene-8,13-diynes were prepared to test [2+2+2] cycloisomerization processes catalyzed by transition metals. The RhCl(CO)(PPh3)2 complex was found to catalyze the cycloisomerization reaction giving the desired cycloadducts in high yields.

Research has been conducted on the cyclometalated compounds. The sulfide substitution reactions by phosphines on the Pt(IV) complexes which possess cyclometalated imine ligands, methyl groups and halogen and sulfide as ligands have been investigated and the results are reported.

Research describes the synthesis, structure, spectroscopic, and electrochemical characterization of ruthenium-bpea complexes starting with ruthenium compounds. The complexes belong to the monoclinic P2(sub)1/m space group with the ruthenium metal center exhibiting a distorted octahedral geometry. They maintain their structure in aqueous solution.

Research describes the stereoselective synthesis of unique dehydro amino acids that are employed in the synthesis of alpha-amino acids. Results reveal that (-)-alpha-pinene serves as the starting raw material to obtain cyclobutane ring and chiral centers for preparing chiral cyclobutane synthons.

The reaction of n-cinnamylpyridinium tetrafluoroborates with Pd(dba)2 and the respective ligand leads to (1-{dimethylamino}-2-{diphenylphosphino}ethane)- (eta3-1-arylallyl)palladium tetrafluoroborates (3). The trans form of the compounds 3 predominates. For the compounds 3, the NMR chemical shifts (delta{sub X}-delta{sub H}) where X ranges between NO2 to OMe, are comparable to the delta Hammett substitution constants. The C-3 atom is trans to the positive charge of the amine ligand.

Mechanistic details of a mild aromatic C-H activation effected by a copper(II) center ligated in a triazamacrocylic ligand which produce equimolar amounts of a [Cu.sup.III]-aryl species and [Cu.sup.I] species as reaction products is reported. The reaction kinetics strongly implicates a rate-limiting proton-coupled electron transfer as the key C-H activation step and the mechanism does not conform to the C-H activation mechanism in a [Ni.sup.II] analogue.

A new set of Ru-Cl complexes containing either the pinene[5,6]bpea ligand (L1) or the [C.sub.3] symmetric pinene[4,5]tpmOMe (L2) tridentate ligand in combination with the bidentate (B) 2,2'-bipyridine (bpy) or 1,2-diphenylphosphinoethane (dppe) ([RuCl(L1 or L2)(B)].sup.+]) are prepared and characterized. The studies have shown that for complexes containing the bpea ligand electronic factors have played a key role.

New isomeric ruthenium complexes containing the bpea ligand (where bpea = N,N-bis-(2-pyridylmethyl)ethylamine) and coordinating in both the meridional and facial fashion are synthesized. Its characteristics and structure are studied using NMR spectroscopy, x-ray diffraction and cyclic voltammetry methods.

Molecular recognition between different dicarboxylic acids and hexaazamacrocyclic ligands is studied using NMR spectroscopy and potentiometric titrations. The adaptation of P3 ligand to the geometry of dicarboxylic acid results in formation of hydrogen bonds.

The synthesis of a family of new Ru complexes containing meridional or facial tridentate ligands with general formula is described. All complexes are spectroscopically characterized in solution through [sup.1.H] NMR and UV-vis techniques.

A family of Ru(II)-Cl complexes bearing the N-tridentate N,N-bis(2-pyridylmethyl)ethylamine (bpea) ligand and the P-bidentate (1,2-diphenylphosphino)ethane (dppe) ligand is described. A strong influence of the facial versus meridional geometry in the bpea ligand coordination mode is seen for these catalytic reactions, with the meridional isomer being much more active than the facial one and even capable of carrying out the H-transfer reaction of bulky substrates such as 2,2-dimethylpropiophenone (DP) at room temperature.

The preparation of new polypyridylic chiral ligands having either [C.sub.3] or lower symmetry via a de novo construction of the pyridine nucleus by means of Krohnke methodology is presented. The preliminary catalytic results performed with the Ru complex (-)-21 show moderate enantioselectivities in styrene epoxidation with PhI[(AcO).sub.2].

The synthesis and the spectroscopic and structural characterization, both in the solid state and in solution, of a Ru complex, cis-fac-DELTA-[Ru(super II)Cl{(R)-(bpea)}{(S)-(BINAP)}](BF4) are reported. The performance of this complex in the homogenous phase as a catalyst for the efficient and stereoselective hydrogenation of prochiral substrates, such as dehydroamino acids, dimethyl itaconate and methylacetoacetate, is discussed.

The productive synthesis of tetrapeptide containing cyclobutane and beta-alanine sediments is explained. Analytical computations predict a most stable folded conformation corresponding to a 14-helix stabilized by a hydrogen bond.

Molecular recognition of diphosphate is achieved through the formation of anionic complexes with isomeric hexaazamacrocyclic ligands. A selectivity of over eighty-eight percent is achieved for the diphosphate complexation, when using the meta isomer over the para, due solely to the size and shape of the receptors cavity.

Research has been conducted on dinuclear copper(I) complexes with hexaaza macrocyclic ligand. The authors describe the synthesis and spectroscopic characterization of these complexes.

Research has been conducted on isomeric ruthenium(II) complexes with dinucleating bis(2-pyridyl)pyrazole ligand. The author report the preparation of these complexes together with Cl nd dmso ligands, and the study of their structural, electrochemical, spectroscopic, catalytic and photochemical properties.

Reaction mechanisms for the oxidations of several substrates by Ru(super IV) = O was established and catalytic oxidations systems were described to get an insight into the rich oxidative properties of the Ru(super IV) = O species. The results show inverse correlation between the ratio of cis/trans epoxide isomerization in the catalytic oxidation of cis-beta-methylstyrene and (DELTA)E(sub 1/2) and only traces of the trans epoxide were formed when using cis-2 and trans-2 complexes as catalysts, demonstrating that the process was highly stereoselective.

Background: Tropical rainforests are frequently limited by soil nutrient availability. However, the response of the metabolic phenotypic plasticity of trees to an increase of soil nutrient availabilities is poorly understood. We expected that increases in the ability of a nutrient that limits some plant processes should be detected by corresponding changes in plant metabolome profile related to such processes. Methodology/Principal findings: We studied the foliar metabolome of saplings of three abundant tree species in a 15 year field NPK fertilization experiment in a Panamanian rainforest. The largest differences were among species and explained 75% of overall metabolome variation. The saplings of the large canopy species, Tetragastris panamensis, had the lowest concentrations of all identified amino acids and the highest concentrations of most identified secondary compounds. The saplings of the “mid canopy” species, Alseis blackiana, had the highest concentrations of amino acids coming from the biosynthesis pathways of glycerate-3P, oxaloacetate and α-ketoglutarate, and the saplings of the low canopy species, Heisteria concinna, had the highest concentrations of amino acids coming from the pyruvate synthesis pathways. Conclusions/Significance: The changes in metabolome provided strong evidence that different nutrients limit different species in different ways. With increasing P availability, the two canopy species shifted their metabolome towards larger investment in protection mechanisms, whereas with increasing N availability, the sub-canopy species increased its primary metabolism. The results highlighted the proportional distinct use of different nutrients by different species and the resulting different metabolome profiles in this high diversity community are consistent with the ecological niche theory. [ABSTRACT FROM AUTHOR]

A facile and stereoselective method is described for the preparation of fused 2,3‐γ‐butyrolactones of lyxofuranose from the unexpected rearrangement in basic media of the photocycloadduct between homochiral 2(5H)‐furanones and vinylene carbonate. †This paper is dedicated to Professor Gérard Descotes on the occasion of his 70th birthday. [ABSTRACT FROM AUTHOR]

Abstract: Selective and efficient preparation of a new chiral dipalladium(0) complex with an olefinic macrocyclic ligand named (E,E,E,E,E,E)-1,6,11,16,21,26-hexakis[(4-methylphenyl)sulfonyl]-1,6,11,16,21,26-hexaazacyclotriaconta-3,8,13,18,23,28-hexaenedipalladium(0) (5) is reported. Dinuclear palladium(0) complex 5 has been fully characterized by means of NMR spectroscopy and X-ray diffraction analysis. [Copyright &y& Elsevier]

Several derivatives of (+)- and (-)-2-aminocyclobutane-l-carboxylic acid, 1, have been prepared through enantiodivergent synthetic sequences. The stereoselective synthesis of free amino acid (+)-1 has been achieved, and this product has been fully characterized for the first time. Stereocontrolled alternative synthetic methodologies have been developed for the preparation of bis(cyclobutane) β-dipeptides in high yields. Among them, enantio and diastereomers have been synthesized, β,β- and β,δ-Dimers resulting from the coupling of a cyclobutane residue and a linear amino acid have also been prepared. The ability of the cyclobutane ring as a structure-promoting unit both in the monomers and in the dimers has been manifested. The NMR structural study and DFT theoretical calculations evidence the formation of strong intramolecular hydrogen bonds giving rise to cis-fused [4.2.0]octane structural units that confer high rigidity on these molecules both in solution and in the gas phase. The contribution of a cis—trans conformational equilibrium derived from the rotation around the carbamate N—C(O) bond has also been observed, the trans form being the major conformer. In the solid state, this equilibrium does not exist, and moreover, intermolecular hydrogen bonds are present. [ABSTRACT FROM AUTHOR]

Two dicopper(I) complexes containing tertiary N-methylated hexaaza ligands which impose different steric constraints to the Cu ions have been synthesized, and their reactivity toward O2 has been compared with a mononuclear related system, highlighting the importance of cooperative effects between the metal centers in O2 activation. [ABSTRACT FROM AUTHOR]