Search results for "Halogen"
showing 10 items of 434 documents
The Effect of Halogen Bonding on the Packing of Bromine Substituted Pyridine and Benzyl Functionalized Resorcinarene Tetrapodands in the Solid State
2012
The synthesis and characterization of new bromine-substituted pyridine and benzyl functionalized tetramethoxy resorcinarene tetrapodands are described and their solid-state structural properties and interactions were studied by single crystal X-ray crystallography. Three different crystal structures were obtained for the pyridine derivative and one for the benzyl derivative, which revealed that the interactions of the bromine substituent have an explicit effect on the crystal packing of the resorcinarene molecules. One of the structures obtained had very interesting halogen–halogen interactions with the same geometry as is generally found for compounds used in nonlinear optical studies.
Supercritical Carbon Dioxide: A Promoter of Carbon-Halogen Bond Heterolysis
2013
as the leaving groupdeparts from the carbon atom prior to the entrance of thenucleophile. Polar protic solvents with high dielectric con-stants promote polar bond heterolysis by providing effectiveH-bonding and electron-pair donation interactions to theleaving group and the incipient carbocation, respectively.Then, the solvent captures the carbocation intermediate togive the corresponding S
Halogen bonding—a key step in charge recombination of the dye-sensitized solar cell
2011
The halogen bonding between [Ru(dcbpy)(2)(SCN)(2)] dye and I(2) molecule has been studied. The ruthenium complex forms a stable [Ru(dcbpy)(2)(SCN)(2)]···I(2)·4(CH(3)OH) adduct via S···I interaction between the thiocyanate ligand and the I(2) molecule. The adduct can be seen as a model for one of the key intermediates in the regeneration cycle of the oxidized dye by the I(-)/I(3)(-) electrolyte in dye sensitized solar cells.
Halogen bond directionality translates tecton geometry into self-assembled architecture geometry
2013
The structures of halogen-bonded infinite chains involving two diiodoperfluoroalkanes and a bent bis(pyrid-4′-yl)oxadiazole show that the geometry of the pyridyl pendant rings is translated into the angle between the formed halogen bonds.
Crystallography of encapsulated molecules.
2017
The crystallography of supramolecular host–guest complexes is reviewed and discussed as a part of small molecule crystallography. In these complexes, the host binds the guests through weak supramolecular interactions, such as hydrogen and halogen bonding, cation–π, anion–π, C–H–π, π–π, C–H–anion interactions and the hydrophobic effect. As the guest often shows severe disorder, large thermal motion and low occupancies, the reliable crystallographic determination of the guest can be very demanding. The analysis of host–guest interactions using tools such as Hirshfeld and cavity volume surface analysis will help to look closely at the most important host–guest interactions. The jewel in the cr…
Modification of the supramolecular structure of [(thione)IY] (Y = Cl, Br) systems by cooperation of strong halogen bonds and hydrogen bonds
2015
Four interhalogen complexes of heterocyclic thione ligands N-methylbenzothiazole-2-thione (mbtt) and 2(3)H-benzothiazole-thione (btt) with strong and tunable S⋯I halogen bonds were synthesized and characterized by X-ray single crystal diffraction. The study of the strength and nature of the interactions was supported by computational analysis using the Quantum Theory of Atoms in Molecules (QTAIM). Halogen bond and hydrogen bond directed self-assemblies of thione compounds were efficiently modified by the changes in the halogen bond donor and acceptor structures. In structures [(mbtt)ICl] (1) and [(mbtt)IBr] (2) the interplay of halogen bonds and hydrogen bonds between the thione hydrogens a…
Synthesis of Highly Functionalized Fluorinated Cispentacin Derivatives
2012
Fluorinated highly functionalized cispentacin derivatives were synthetised starting from an unsaturated bicyclic b-lactam through C¼C bond functionalization via the dipolar cycloaddition of a nitrile oxide, isoxazoline opening, and fluorination by OH/F exchange.
Synthesis of iodobiaryls and dibenzofurans by direct coupling at BDD anodes.
2014
The first direct oxidative phenol-arene cross-coupling reactions of an iodine-containing guaiacol derivative and the possible over-oxidation products of electron-rich phenols are described. Hereby, a "green" and targeted synthesis for dibenzofurans was developed.
Highly Fluorinated 2,2′-Biphenols and Related Compounds: Relationship between Substitution Pattern and Herbicidal Activity
2013
A broad range of halogenated 2,2'-biphenols was tested for applicability as crop protection agents. The activity of these compounds toward four typical pest plants was observed after application by spraying of diluted solutions. Despite their rather simple structure, it was found that the studied compounds reveal a surprisingly high herbicidal impact. To gain a better understanding of the structure-activity relationship, specific sites of the molecule were chemically modified and the core structures thus gradually changed. The influence of the substitution pattern on the herbicidal properties is discussed, and conclusions on the active site of the biphenol structure are drawn. It was observ…
Fluorine Scan of Inhibitors of the Cysteine Protease Human Cathepsin L: Dipolar and Quadrupolar Effects in the π-Stacking of Fluorinated Phenyl Rings…
2016
The π-stacking of fluorinated benzene rings on protein backbone amide groups was investigated, using a dual approach comprising enzyme-ligand binding studies complemented by high-level quantum chemical calculations. In the experimental study, the phenyl substituent of triazine nitrile inhibitors of human cathepsin L (hCatL), which stacks onto the peptide amide bond Gly67-Gly68 at the entrance of the S3 pocket, was systematically fluorinated, and differences in inhibitory potency were measured in a fluorimetric assay. Binding affinity is influenced by lipophilicity (clog P), the dipole and quadrupole moments of the fluorinated rings, but also by additional interactions of the introduced fluo…