Search results for "AGN"
showing 10 items of 28126 documents
Cytosine Nucleobase Ligand: A Suitable Choice for Modulating Magnetic Anisotropy in Tetrahedrally Coordinated Mononuclear CoII Compounds
2017
A family of tetrahedral mononuclear CoII complexes with the cytosine nucleobase ligand is used as the playground for an in-depth study of the effects that the nature of the ligand, as well as their noninnocent distortions on the Co(II) environment, may have on the slow magnetic relaxation effects. Hence, those compounds with greater distortion from the ideal tetrahedral geometry showed a larger-magnitude axial magnetic anisotropy (D) together with a high rhombicity factor (E/D), and thus, slow magnetic relaxation effects also appear. In turn, the more symmetric compound possesses a much smaller value of the D parameter and, consequently, lacks single-ion magnet behavior.
A two-dimensional coordination polymer constructed from binuclear copper(II) metalloligands and manganese(II) ions: Synthesis, crystal structure and …
2016
Abstract The self-assembly process between the binuclear [Cu2(HL)(L)]− complex and the manganese(II) ion affords a two-dimensional coordination polymer of formula [Mn{Cu2(HL)(L)}2(H2O)2]n (1) (H3L = 3-hydroxyiminomethylsalicylic acid) where parallel ladder-like motifs of defective double cubanes of bis(phenoxo)dicopper(II) units as rods and anti-syn carboxylato bridges as rungs act as ligands towards tetraaqua-manganese(II) entities through the deprotonated oxime groups. The topology of 1 is compared with the one of another compound, [Mn{Cu2(HL)(L)}2(H2O)4]·4H2O·2DMF (1′) which was obtained in different conditions by Okawa et al. (J. Chem. Soc., Dalton Trans. (2001) 3119). Magnetic suscepti…
Synthesis, crystal structure and magnetic properties of a cyanide-bridged heterometallic {CoIIMnIII} chain
2017
The assembly reaction between the low-spin [CoII(dmphen)(CN)3]- metalloligand and the [MnIII(salen)(H2O)]+ complex cation yielded the one-dimensional compound {[MnIII(salen)(μ-NC)2CoII(dmphen)(CN)]·2H2O}n (1), which behaves as a ferrimagnetic chain, the intrachain magnetic coupling being J = -1.71(1) cm-1.
Molecular materials based upon organic π-donors and magnetic anions
2000
Electrochemical combination of the magnetic dinuclear anion [MM'(C 2 O 4 )(NCS) 8 ] 4- (MM' = CrCr, CrFe) or paramagnetic mononuclear anion [Cr(NCS) 6 ] 3- with the ET organic π-donor (ET = BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) gives rise to two new series of molecular hybrid salts formulated (ET) 5 [MM'(C 2 O 4 )(NCS) 8 (MM' = CrCr (1), CrFe (2)), (ET) 8 [MM'(C 2 O 4 )(NCS) 8 ] (3), (ET) 5.5 f Cr(NCS) 6 ] (4) and (ET) 5 [(C 2 H 5 ) 4 N] [Cr(NCS) 6 ](THF) (5) (THF = tetrahydrofuran). The crystal structures consist of alternating organic and inorganic layers. The organic part does not produce any detectable effect on the magnetic properties coming from the inorganic sublattice. T…
Determining Factors for the Unfolding Pathway of Peptides, Peptoids, and Peptidic Foldamers.
2016
We present a study of the mechanical unfolding pathway of five different oligomers (α-peptide, β-peptide, δ-aromatic-peptides, α/γ-peptides, and β-peptoids), adopting stable helix conformations. Using force-probe molecular dynamics, we identify the determining structural factors for the unfolding pathways and reveal the interplay between the hydrogen bond strength and the backbone rigidity in the stabilization of their helix conformations. On the basis of their behavior, we classify the oligomers in four groups and deduce a set of rules for the prediction of the unfolding pathways of small foldamers.
Synthesis, crystal structure and magnetic properties of two oxalato-bridged dimetallic trinuclear complexes combined with a polar cation
2010
Two isostructural heterometallic trinuclear oxalato-bridged complexes of formula C(4)[MCr(2)(ox)(6)(H(2)O)(2)]·nH(2)O (C(+) = 4-aminopyridinium; ox(2-) = oxalate dianion; M(2+) = Mn(2+), n = 3, 1; M(2+) = Co(2+), n = 3.25, 2) have been synthesized by using direct self-assembly methods combining C(3)[Cr(ox)(3)] and the chloride salts of the corresponding metal ion. The crystal structures of both compounds have been resolved by single-crystal X-ray diffraction. They crystallize in the C2/c space group [a = 11.5113(15) Å, b = 20.250(3) Å, c = 21.810(4) Å, beta = 100.447(10) degrees, V = 5161.6(3) Å(3), and Z = 4 for 1, and a = 11.4334(16) Å, b = 20.243(2) Å, c = 21.805(3) Å, beta = 101.113(9) …
Helical supramolecular polymerization of C3-symmetric amides and retroamides: on the origin of cooperativity and handedness.
2016
The cooperative supramolecular polymerization of 1 and 2 yields P- or M-type helical aggregates depending on the absolute configuration (S or R) of the stereogenic centres attached to the side chains. The connectivity of the amide group does not affect the handedness of the helical aggregates, but determines a larger cooperativity for retroamides 1.
Nonanuclear Spin-Crossover Complex Containing Iron(II) and Iron(III) Based on a 2,6-Bis(pyrazol-1-yl)pyridine Ligand Functionalized with a Carboxylat…
2016
The synthesis and magnetostructural characterization of [Fe(III)3(μ3-O)(H2O)3[Fe(II)(bppCOOH)(bppCOO)]6](ClO4)13·(CH3)2CO)6·(solvate) (2) are reported. This compound is obtained as a secondary product during synthesis of the mononuclear complex [Fe(II)(bppCOOH)2](ClO4)2 (1). The single-crystal X-ray diffraction structure of 2 shows that it contains the nonanuclear cluster of the formula [Fe(III)3(μ3-O)(H2O)3[Fe(II)(bppCOOH)(bppCOO)]6](13+), which is formed by a central Fe(III)3O core coordinated to six partially deprotonated [Fe(II)(bppCOOH)(bppCOO)](+) complexes. Raman spectroscopy studies on single crystals of 1 and 2 have been performed to elucidate the spin and oxidation states of iron …
Synthesis and characterization of binuclear μ-oxalato nickel(II), copper(II) and zinc(II) complexes with 3,3′-diamino-N-methyl-dipropylamine or trans…
1999
Abstract New binuclear complexes of the type [(Ni(Medpt)NO3)2ox] (1) (Medpt=3,3′-diamino-N-methyl-dipropylamine, H2ox=oxalic acid), [(Ni(dach)2)2ox]NO3·2H2O (2) (dach=trans-1,2-diaminocyclohexane), [(Cu(Medpt))2ox]X2·yH2O (X=NO3, y=2 2/3 (3); X=ClO4, y=0 (4)) and [(Zn(dach)2)2ox](ClO4)2·2H2O (5) have been prepared and characterized by IR and UV–Vis spectroscopies. Spectroscopic data are consistent with oxalate-bridged structures between six-coordinated (N3O3 or N4O2) Ni(II) (compounds 1 or 2), five-coordinated (N3O2) Cu(II) (compounds 3 and 4) or six-coordinated (N4O2) Zn(II) (compound 5). The crystal structure of [(Cu(Medpt))2ox](NO3)2·2 2/3 H2O (3) has been determined by single-crystal X-…
Application of Rigidity-Controlled Supramolecular Affinity Materials for the Gravimetric Detection of Hazardous and Illicit Compounds.
2016
The combination of an (-)-isosteviol-derived building block and 9,9'-spirobifluorene or tetraphenylmethane generated highly potent new affinity materials for the detection of volatile organic compounds (VOCs). Comparison of their affinity behaviour with different core structures showed remarkable influence on selectivity and sensitivity due to structural rigidity and their pre-organization. Their unique supramolecular properties were investigated in an affinity assay using high fundamental frequency quartz crystal microbalances.