Search results for "405"

Polymere Selectinliganden als komplexe Glykomimetika: von Selectinbindung bis zur Modifizierung der Makrophagenmigration

2016

Bei neuartigen polymeren Inhibitoren der Zelladhasion wird das Selectin-bindende Tetrasaccharid Sialyl-LewisX (SLeX) multivalent auf einem biokompatiblen Poly(2-hydroxypropyl)methacrylamid (PHPMA) entweder alleine (P1) oder in Kombination mit O-sulfatierten Tyramin-Seitenketten (P2) prasentiert. Zum Vergleich wurden entsprechende polymere Glykomimetika hergestellt, in denen die entscheidenden Fucose-, Galactose und Sialinsaure-Seitenketten statistisch verteilt im PHPMA-Ruckgrat (P3 oder P4 (O-sulfatiertes Tyramin) vorliegen. Alle Polymere haben den gleichen Polymerisationsgrad, da sie vom selben Ausgangspolymer abstammen. Assays fur die Bindung an Selectine, aktivierte Endothelzellen und Ma…

Kinetisch kontrolliertes, sequenzielles Wachstum von chiralen supramolekularen Copolymeren auf Oberflächen

2016

Wir berichten uber eine einfache Strategie zur Herstellung supramolekularer Copolymere an Goldoberflachen durch sukzessive Inkubation einer initiatorbeschichteten Oberflache mit Losungen aus gegensatzlich geladenen peptidischen Comonomeren. Ein ladungsreguliertes Wachstum des Polymers verlangsamt die Kinetik der Selbstorganisation in dem Mase, dass kinetisch gehemmte Copolymere im nahezu neutralen pH-Bereich gebildet werden. Auf diese Weise erreichen wir eine Kontrolle der Polymerarchitektur auf drei Ebenen: Die β-faltblattkodierte Peptidsequenz steuert eine Wachstumsrichtung der Polymere senkrecht zur Oberflache, die Hohe der supramolekularen Copolymerbursten wird durch den schrittweisen A…

R�ntgenkristallographische Daten von Bi(NO3)3�5H2O und BiONO3�1/2H2O

1967

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…

Equipping metallo-supramolecular macrocycles with functional groups: Assemblies of pyridine-substituted urea ligands

2012

A series of di-(m-pyridyl)-urea ligands were prepared and characterized with respect to their conformations by NOESY experiments and crystallography. Methyl substitution in different positions of the pyridine rings provides control over the position of the pyridine N atoms relative to the urea carbonyl group. The ligands were used to self-assemble metallo-supramolecular M(2)L(2) and M(3)L(3) macrocycles which are generated in a finely balanced equilibrium in DMSO and DMF according to DOSY NMR experiments and ESI FTICR mass spectrometry. Again, crystallography was used to characterize the assemblies. Methyl substitution in positions next to the pyridine nitrogen prevents coordination, while …

A family of heterotetrameric clusters of chloride species and halomethanes held by two halogen and two hydrogen bonds

2016

Two previously reported 1,3,5,7,9-pentaazanona-1,3,6,8-tetraenate (PANT) chloride platinum(II) complexes [PtCl{HNC(R)NCN[C(Ph)C(Ph)]CNC(R)NH}] (R = tBu 1, Ph 2) form solvates with halomethanes 1·1¼CH2Cl2, 1·1⅖CH2Br2, and 2·CHCl3. All these species feature novel complex-solvent heterotetrameric clusters, where the structural units are linked simultaneously by two C–X⋯Cl–Pt (X = Cl, Br) halogen and two C–H⋯Cl–Pt hydrogen bonds. The geometric parameters of these weak interactions were determined using single-crystal XRD, and the natures of the XBs and HBs in the clusters were studied for the isolated model systems (1)2·(CH2Cl2)2, (1)2·(CH2Br2)2, and (2)2·(CHCl3)2 using DFT calculations and Bad…