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Latter Complexes (latter + complex)

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Chemistry	100%

Selected Abstracts

The Synthesis, Characterisation, and Reactivity of Some Polydentate Phosphinoamine Ligands with Benzene-1,3-diyl and Pyridine-2,6-diyl Backbones

HELVETICA CHIMICA ACTA, Issue 10 2003
Nermin Biricik
The polydentate phosphinoamines 1,3-{(Ph2P)2N}2C6H4 and 2,6-{(Ph2P)2N}2C5H3N have been prepared in a single step from the reaction of the amines 1,3-(NH2)2C6H4 or 2,6-(NH2)2C5H3N with Ph2PCl in presence of Et3N (1,:,4,:,4 molar ratio) in CH2Cl2. Reaction of 1,3-{(Ph2P)2N}2C6H4 or 2,6-{(Ph2P)2N}2C5H3N with elemental sulfur or selenium in CH2Cl2 affords the corresponding tetrasulfide or tetraselenide, respectively, in good yield. The complexes [1,3-{Mo(CO)4(Ph2P)2N}2(C6H4)] and [2,6-{Mo(CO)4(Ph2P)2N}2(C5H3N)] were prepared from the reaction of these phosphinoamines with [Mo(CO)4(nbd)] (nbd=norbornadiene) in toluene, and the structure of the latter complex has been determined by single-crystal X-ray diffraction analysis. [source]

Theoretical studies on the structure and protonation of Cu(II) complexes of a series of tripodal aliphatic tetraamines: Good correlations with the experimental data

JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 13 2010
Sadegh Salehzadeh
Abstract DFT(B3LYP) studies on first protonation step of a series of Cu(II) complexes of some tripodal tetraamines with general formula N[(CH2)nNH2][(CH2)mNH2][(CH2)pNH2] (n = m = p = 2, tren; n = 3, m = p = 2, pee; n = m = 3, p = 2, ppe; n = m = 3, tpt; n = 2, m = 3, p = 4, epb; and n = m = 3, p = 4; ppb) are reported. First, the gas-phase proton macroaffinity of all latter complexes was calculated with considering following simple reaction: [Cu(L)]2+(g) + H+(g) , [Cu(HL)]3+(g). The results showed that there is a good correlation between the calculated proton macroaffinities of all complexes with their stability constants in solution. Then, we tried to determine the possible reliable structures for microspecies involved in protonation process of above complexes. The results showed that, similar to the solid state, the [Cu(L)(H2O)]2+ and [Cu(HL)(H2O)2]3+ are most stable species for latter complexes and their protonated form, respectively, at gas phase. We found that there are acceptable correlations between the formation constants of above complexes with both the , and , of following reaction: [Cu(L)(H2O)]2+(g) + H+(g) + H2O(g) , [Cu(HL)(H2O)2]3+(g). The , of the latter reaction can be defined as a theoretically solvent,proton macroaffinity of reactant complexes because they have gained one proton and one molecule of the solvent. The unknown formation constant of [Cu(epb)]2+ complex was also predicted from the observed correlations. In addition, the first proton affinity of all complexes was studied in solution using DPCM and CPCM methods. It was shown that there is an acceptable correlation between the solvent,proton affinities of [Cu(L)(H2O)]2+ complexes with formation constants of [Cu(HL)(H2O)2]3+ complexes in solution. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 [source]

Aggregation and membrane permeabilizing properties of designed histidine-containing cationic linear peptide antibiotics,

JOURNAL OF PEPTIDE SCIENCE, Issue 4 2008
Arnaud Marquette
Abstract Members of the LAH4 family of cationic linear peptide antibiotics have been designed to form amphipathic helical structures in membrane environments and switch from alignments parallel to the bilayer surface to transmembrane orientations in a pH-dependent manner. Here the aggregation in aqueous buffer of two members of the family has been investigated by DLS. The peptides form monomers or small oligomers at pH = 5 but associate into nano-sized aggregates at physiological pH. The diameter of these latter complexes can be considerably reduced by sonication. Furthermore, the membrane interactions of the various supramolecular aggregates with POPC or mixed POPC/POPS vesicles have been investigated in calcein-release assays. In all the cases tested, the large preformed oligomeric peptide aggregates of 20,40 nm in size were more active than the structures with the smallest hydrodynamic radii in releasing the fluorescent dye from LUV. In contrast, the relative activity after sonication depends on the specific environment tested. The data suggest that these amphiphiles form micellar structures and support the notion that they can act in a manner comparable to detergents. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source]

Stabilization of High-Valent FeIVS6 -Cores by Dithiocarbamate(1,) and 1,2-Dithiolate(2,) Ligands in Octahedral [FeIV(Et2dtc)3,n(mnt)n](n,1), Complexes (n=0, 1, 2, 3): A Spectroscopic and Density Functional Theory Computational Study,

CHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2010
Carsten Milsmann Dr.
Abstract A detailed spectroscopic and quantum chemical analysis is presented to elucidate the electronic structures of the octahedral complexes [Fe(Et2dtc)3,n(mnt)n]n, (1,4, n=3, 2, 1, 0) and their one-electron oxidized analogues [Fe(Et2dtc)3,n(mnt)n](n,1), (1ox,4ox); (mnt)2, represents maleonitriledithiolate(2,) and (Et2dtc)1, is the diethyldithiocarbamato(1,) ligand. By using X-ray crystallography, Mössbauer spectroscopy, and Fe and S K-edge X-ray absorption spectroscopy (XAS) it is convincingly shown that, in contrast to our previous studies on [Fe(cyclam)(mnt)]1+ (cyclam=1,4,8,11-tetraazacyclotetradecane), the oxidation of 1,4 is metal-centered yielding the genuine FeIV complexes 1ox,4ox. For the latter complexes, a spin ground state of S=1 has been established by magnetic susceptibility measurements, which indicates a low-spin d4 configuration. DFT calculations at the B3LYP level support this electronic structure and exclude the presence of a ligand , radical coordinated to an intermediate-spin ferric ion. Mössbauer parameters and XAS spectra have been calculated to calibrate our computational results against the experiment. Finally, a simple ligand-field approach is presented to correlate the structural features obtained from X-ray crystallography (100,K) with the spectroscopic data. [source]