Search results for "Halogen"
showing 10 items of 434 documents
Photoresponsive ionic liquid crystals assembled: Via halogen bond: En route towards light-controllable ion transporters
2017
We demonstrate that halogen bonding (XB) can offer a novel approach for the construction of photoresponsive ionic liquid crystals. In particular, we assembled two new supramolecular complexes based on 1-ethyl-3-methylimidazolium iodides and azobenzene derivatives containing an iodotetrafluoro-benzene ring as XB donor, where the iodide anion acted as an XB acceptor. DSC and X-ray diffraction analyses revealed that the preferred stoichiometry between the XB donors and acceptors is 2 : 1, and that the iodide anions act as bidentate XB-acceptors, binding two azobenzene derivatives. Due to the high directionality of the XB, calamitic superanions are obtained, while the segregation occurring betw…
Solid state halogen bonded networks vs. dynamic assemblies in solution: explaining N⋯X interactions of multivalent building blocks
2015
Tetrapyridine functionalized resorcinarene macrocycles were used as multivalent building blocks for the construction of halogen bonded networks with aryl halide linkers. In the solid state, resorcinarene macrocycles and aryl halide linker molecules assembled into interpenetrated, multidimensional halogen bonded networks with porous structure caused by the 3D block scaffold of the resorcinarenes. 19F NMR spectroscopy proved halogen bond formation also in solution, as either upfield or downfield shifts were observed depending on the bivalent or monovalent halogen bond binding mode. The binding mode in solution was explained by density functional theory computations. peerReviewed
Properties and interactions – melting point of tribromobenzene isomers
2021
The melting points of tribromobenzene isomers are correlated with the number, nature and distribution of intermolecular interactions in their structures.
The Synergetic Interplay of Weak Interactions in the Ion-Pair Recognition of Quaternary and Diquaternary Ammonium Salts by Halogenated Resorcinarenes
2013
The influence of halogens on the noncovalent interactions of different upper-rim-substituted hexylresorcinarenes with quaternary and diquaternary ammonium iodide salts was investigated in the gas phase by electrospray ionization Fourier-transform ion-cyclotron-resonance (ESI-FTICR) mass spectrometry and in solution by 1H NMR titration studies. The electronic nature of the substituents on the upper rim of the resorcinarene was directly reflected in the order of binding strengths of the hosts towards quaternary and diquaternary ammonium cations in the gas phase. In solution, the opposite trend was observed, with generally higher binding constants for the diquaternary over the quaternary salts…
Different structural destinations: comparing reactions of [CuBr2(3-Brpy)2] crystals with HBr and HCl gas
2011
Reaction of green crystalline solid trans-[CuBr2(3-Brpy)2] 1 (3-Brpy = 3-bromopyridine) with HBr (aq) vapour yields brown crystalline salt (3-BrpyH)2[CuBr4] 2 with quantitative conversion. Notably 2 adopts a different crystal structure to the three mutually isostructural compounds (3-XpyH)2[CuCl4] (X = Cl, Br) and (3-BrpyH)2[CuBr2Cl2] which result from reaction with HCl. Crystalline product 2 has been characterised by X-ray powder diffraction and its conversion back to 1 at 370–400 K has been followed in situ by synchrotron X-ray powder diffraction. Crystalline 1 and 2 are further notable for the presence of intermolecular C–Br⋯Br–Cu halogen bonds and (only in the case of 2) N–H⋯Br–Cu hydro…
Non-Isomorphic Chlorine—Bromine Substitution in the Copper(I) Halideπ-Complexes with 1-Allyl-4-aminopyridinium
2003
By alternating-current electrochemical synthesis crystals of {Cu[H2NC5H4N(C3H5)]Br2}˙H2O (I), {Cu[H2NC5H4N(C3H5)]Br0.65Cl1.35}˙H2O (II) and {Cu[H2NC5H4N(C3H5)]Cl2} (III) π-complexes have been obtained and structurally investigated. The I and II compounds are isostructural and crystallize in a monoclinic sp. gr. P21/c, I: a = 7.359(2)A, b = 12.3880(6)A, c = 13.637(3)A, β = 107.03(1)°, V = 1188.7(4)A3, Z = 4 for C8H13N2OBr2Cu composition, R = 0.0293 for 2140 reflections. II: a = 7.2771(6)A, b = 12.3338(3)A, c = 13.4366(7)A, β = 107.632(2)°, V = 1149.3(1)A3, Z = 4 for C8H13N2Br0.65Cl1.35Cu composition, R = 0.0463 for 2185 reflections. Metal and halogen atoms form centrosymmetric Cu2X4 dimers. …
Iodine speciation in marine aerosols along a 30,000 km round-trip cruise path from Shanghai, China to Prydz Bay, Antarctica
2008
[1] Total suspended particle (TSP) samples were collected onboard a round-trip cruise from Shanghai, China to Prydz Bay, Antarctica from November 2005 to March 2006. Water soluble iodine species were measured using ion chromatography coupled to Inductively Coupled Plasma-Mass Spectrometry (IC-ICP-MS). The results reveal that soluble organic iodine (SOI) is the most abundant fraction, accounting for approximately 70 % of total soluble iodine (TSI) on average. One unidentified organic iodine (UOI) signal was present in almost all of the samples and was responsible for up to 38.3% of TSI. The abundance of inorganic iodine species, iodate and iodide, was less than 30% of TSI. Iodide was signifi…
Synthesis of brominated tetrathiafulvalenes via phosphite-mediated cross-coupling
2010
The synthesis of polybrominated tetrathiafulvalenes (TTF-Brn, 2-4) containing 2-4 bromine atoms via phosphite-mediated cross-coupling of bromo-substituted 1,3-dithiole-2-thiones and 1,3-dithiole-2-ones is reported. © 2010 Elsevier B.V.
Oxidative halogenation of substituted pyrroles with Cu(II). PartIII. Bromination and chlorination of 2-benzoylpyrrole
1992
The bromination of 2-benzoylpyrrole with copper(II) bromide in the homogeneous and the heterogeneous phase is described, giving 4- and 5-monobromo derivatives whose ratio decreases as the temperature is increased. The same reaction with copper(II) chloride in acetonitrile at 60° produces 5-chloro-2-benzoylpyrrole as the major product. 4,5-Dihalopyrroles in good yields are obtained with an excess of halogenating agent.
Influence of the nature of the substrate and of operative parameters in the electrocarboxylation of halogenated acetophenones and benzophenones
2005
Abstract The electrocarboxylation of halogenated acetophenones and benzophenones to the corresponding hydroxycarboxylic acids has been carried out in undivided cell equipped with aluminium sacrificial anode and using 1-methyl-2-pyrrolidinone (NMP) as the solvent. The radical anion generated by the electro-reduction of the aromatic ketone is involved in several competitive reactions which lead to the formation of the target hydroxycarboxylic acid, the corresponding alcohol and pinacol and the de-halogenated parent ketone. If sufficiently negative working potentials are imposed, the latter is reduced to the corresponding carboxylate, pinacol and alcohol. Very different results in terms of sel…