Search results for "ECU"
showing 10 items of 42395 documents
Insight into the Mechanism of Water Adsorption/Desorption in Hydrophilic Viologen-Carboxylate Based PCP
2017
A water stable and highly hydrophilic porous coordination polymer based on viologen-carboxylate type ligand, the 4,4′-bipyridinium,1,1-bis(3-carboxyphenyl) (pc2), is obtained by the solvothermal method: [Cd3(pc2) (BTC)2(H2O)2]·6H2O ([1(H2O)2]·6H2O; BTC3– = 1,3,5-carboxybenzene). Its crystal structure and the ones of two partially dehydrated phases have been determined, allowing insight into the mechanism of water adsorption/desorption of this PCP material. It is shown that the dehydrated compound [1] first adsorbs two water molecules which fill the pores, leading to [1]·2H2O. On the other hand, the partial dehydration of the as-synthesized compound leads to the intermediate phase [1(H2O)]·3…
A novel two-dimensional organostannoxane coordination network promoted by phenazine: Synthesis, characterization and X-ray structure of
2009
Abstract Reaction of the dimeric hydroxo di-n-butylstannane trifluoromethanesulfonato complex [n-Bu2Sn(μ-OH)(H2O)0.5(η1-O3SCF3)]2 (1) with phenazine (C12H8N2, Phz) (2) in dichloromethane at room temperature in a 1:3 molar ratio yielded the novel two-dimensional organometallic coordination polymer 2 ∞ { [ n - Bu 2 ( μ -OH ) SnOSn ( μ - η 2 - O 3 SCF 3 ) n - Bu 2 ] 2 [ n - Bu 2 ( μ -OH ) SnOSn ( η 1 - O 3 SCF 3 ) n - Bu 2 ] 2 } (3), together with the phenazinium trifluoromethanesulfonate salt [C12H9N2]+ [CF3SO3]−, crystallographically isolated in two different structural arrangements, free 4 and in π–π aromatic stacking interaction with independent intercalated non-protonated phenazine molecu…
Supramolecular Architectures Based on Phosphonic Acid Diesters
2014
The interest of phosphonic acid dialkyl esters for generation of metal-organic materials is discussed using derivatives of porphyrin and 1,10-phenanthroline series as representative examples.
New crystal structures of fluorinated α-aminophosphonic acid analogues of phenylglycine
2020
The four novel phosphonic acid analogues of phenylglycine with various substituents in phenyl ring (mostly fluorine atoms) have been synthesized by using procedure of amidoalkylation of phosphorus trichloride with aromatic aldehydes and acetamide. The NMR, ESI-MS spectroscopy, and single-crystal X-Ray diffraction methods were used to characterize unusual structures: the amino-(4-trifluoromethylbenzyl)-(1), amino-(3,4-difluorobenzyl)-(2), amino-(2,4,6-trifluorobenzyl)-(3), and amino-(2-fluoro-4-hydroxybenzyl)-(4) phosphonic acids. Since the α-aminophosphonates have a potential for biological activity and could be used as building blocks in medicinal chemistry, it is important to know their d…
Synthesis, crystal structures and magnetic properties of picolinate-bridged copper(II) chains
2018
The paper reports the synthesis, crystal structures, and magnetic properties of two copper(II) coordination polymers, Cu2(L1)4 (1) and Cu3(L2)6 (2), based on rigid ethynylene-bridged ditopic ligands containing one picolinate subunit (L1 = 5-(pyridin-3-ylethynyl)picolinate anion; L2 = 5-((4-(methoxycarbonyl)phenyl)ethynyl)picolinate anion). Both 1 and 2 have a chain structure. In 1, the repeating unit in the chain is a doubly bridged picolinate dicopper(II) complex, whereas 2 is built upon trimeric units where the Cu2+ ions are also connected by double picolinate bridges. Both compounds exhibit antiferromagnetic interactions in the solid state. The magnetic properties of 1 and 2 were analyze…
A Generalized Semiempirical Approach to the Modeling of the Optical Band Gap of Ternary Al-(Ga, Nb, Ta, W) Oxides Containing Different Alumina Polymo…
2021
A generalization of the modeling equation of optical band gap values for ternary oxides, as a function of cationic ratio composition, is carried out based on the semiempirical correlation between the differences in the electronegativity of oxygen and the average cationic electronegativity proposed some years ago. In this work, a novel approach is suggested to account for the differences in the band gap values of the different polymorphs of binary oxides as well as for ternary oxides existing in different crystalline structures. A preliminary test on the validity of the proposed modeling equations has been carried out by using the numerous experimental data pertaining to alumina and gallia p…
A family of layered chiral porous magnets exhibiting tunable ordering temperatures.
2013
A simple change of the substituents in the bridging ligand allows tuning of the ordering temperatures, Tc, in the new family of layered chiral magnets A[M(II)M(III)(X2An)3]·G (A = [(H3O)(phz)3](+) (phz = phenazine) or NBu4(+); X2An(2-) = C6O4X2(2-) = 2,5-dihydroxy-1,4-benzoquinone derivative dianion, with M(III) = Cr, Fe; M(II) = Mn, Fe, Co, etc.; X = Cl, Br, I, H; G = water or acetone). Depending on the nature of X, an increase in Tc from ca. 5.5 to 6.3, 8.2, and 11.0 K (for X = Cl, Br, I, and H, respectively) is observed in the MnCr derivative. Furthermore, the presence of the chiral cation [(H3O)(phz)3](+), formed by the association of a hydronium ion with three phenazine molecules, lead…
Hydrogen-Bonded Open-Framework with Pyridyl-Decorated Channels: Straightforward Preparation and Insight into Its Affinity for Acidic Molecules in Sol…
2017
International audience; An hydrogen-bonded open framework with pores decorated by pyridyl groups has been constructed following an off-charge-stoichiometry assemblage of protonated tetrakis(4-pyridyl-oxymethyl)methane and [Al(oxalate)3]3-, respectively the H-bond donor and acceptor of the ionic H-bond interactions. This supramolecular porous architecture (SPA-2) possesses 1 nm-large pores interconnected in 3D with high solvent accessible void (53%). It demonstrated remarkable affinity for acidic organic molecules in solution, which was investigated by the means of various carboxylic acids including larger drug molecules. Noteworthy, competing sorption between acetic acid and its halogenated…
Water-Soluble Squaramide Dihydrates: N-Methylation Modulates the Occurrence of One- and Two-Dimensional Water Clusters through Hydrogen Bonding and D…
2018
Water confined in molecular size domains is distinct to bulk water. The altered interactions between adjacent water molecules, and between water molecules and molecular wall components of the confinement system, determine aspects of important phenomena in material science, biology, and nanotechnology. The structural determination of confined water, however, has proven to be challenging. Here, we describe the crystal structures of three related squaramides 1–3 whose molecular structures are modulated by the gradual incorporation of N-methyl groups to the squaramide moiety. The three squaramides differ in their hydrogen bonding capabilities due to the different degree of N-methylation of each…
A polar/π model of interactions explains face-to-face stacked quinoid rings: a case study of the crystal of potassium hydrogen chloranilate dihydrate
2015
International audience; The nature of interactions between face-to-face staggered stacked quinoid rings with pi-systems, observed with a short inter-ring centroid. centroid distance, is analyzed by experimental and theoretical methods. Charge density studies based on X-ray diffraction and DFT calculations, complemented by impedance spectroscopy, were employed to define the electronic and structural characteristics of the quinoid rings responsible for their interactions within the crystal packing. The crystal packing is mainly stabilized by strong electrostatic interactions between the K+ cation and the hydrogen chloranilate anion. The proximity and orientation of the stacked quinoid rings i…