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Chem Commun (Camb) ; 48(80): 9983-5, 2012 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-22950083


A rare anion-π complex between bromide and a neutral receptor is reported and related receptor systems are studied with a series of anions. The interaction is observed in the solid state and in solution, and further evidence for it is obtained by a computational study.

Ânions/química , Benzamidas/química , Brometos/química , Ligação de Hidrogênio , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Conformação Molecular
Carbohydr Res ; 361: 78-82, 2012 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-22986028


The circular dichroism of a series of acyclic polyhydroxyalkyl benzimidazole C-nucleoside analogs was correlated with the stereochemistry of the chiral carbon atom α to the benzimidazole base moiety. This correlation was used for the assignment of the anomeric configuration of 2-(ß-L-erythrofuranosyl) benzimidazole C-nucleoside analogs without a need to have the other anomer on hand, in a similar manner to the correlation obtained for assignment of the anomeric configuration of triazole C-nucleoside analogs.

Benzimidazóis/química , Nucleosídeos/química , Dicroísmo Circular , Estrutura Molecular , Nucleosídeos/síntese química
Dalton Trans ; 41(31): 9316-22, 2012 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-22763814


Triangular triscatechol ligands are prepared in facile reaction sequences. The catechol units are either bound to the triangular backbone through their 3- or 4-position. With titanium(IV) ions, the ligands form metallosupramolecular M(4)L(4) tetrahedra which are characterized by ESI MS and proton NMR. Quantum-chemical calculations reveal that connectivity at the catechol in the 3-position results in highly condensed structures while attachment in the 4-position affords container molecules providing huge internal cavities.

Chemistry ; 16(41): 12446-53, 2010 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-20845416


The directionality of interaction of electron-deficient π systems with spherical anions (e.g,. halides) can be controlled by secondary effects like NH or CH hydrogen bonding. In this study a series of pentafluorophenyl-substituted salts with polyhalide anions is investigated. The compounds are obtained by aerobic oxidation of the corresponding halide upon crystallization. Solid-state structures reveal that in bromide 2, directing NH-anion interactions position the bromide ion in an η(1)-type fashion over but not in the center of the aromatic ring. The same directing forces are effective in corresponding tribromide salt 3. In the crystal, the bromide ion is paneled by four electron-deficient aromatic ring systems. In addition, compounds 4 and 6, which have triiodide and the rare tetraiodide dianion as anions, are described. Computational studies reveal that the latter is highly unstable. In the present case it is stabilized by the crystal lattice, for example, by interaction with electron-deficient π systems.