Résumés Année 1999

"Synthesis and structural analysis of a exo-ditopic fully conjugated macrocyclic ligand bearing two 2,2'- bipyridine units and of its binuclear osmium diastereoisomers"

J. J. LAGREF, M. W. HOSSEINI, J-M. PLANEIX, A. DE CIAN, J. FISCHER, Chem. Comm., 1999, 2155-2156. (download .pdf)

Abstract : The synthesis and structural analysis of a macrocyclic exo-ditopic ligand bearing two 2,2'-bipyridine units interconnected at the 4 and 4' positions by two -(CH2)2Si(CH2)2- spacers and of its acyclic analogue was achieved. For both compounds ruthenium homobinuclear complexes were prepared. In the case of the complex obtained with the cyclic ligand, both diastereoisomers were separated and the structure of the meso form was elucidated by X-ray analysis.

"Molecular Braids : Quintuple Helical Hydrogen Bonded Molecular Network"

W. JAUNKY, M. W. HOSSEINI, J.-M. PLANEIX, A. DE CIAN, N. KYRITSAKAS, J. FISCHER, Chem. Comm., 1999, 2313-2314. (download .pdf)

Abstract : The synthesis of 1 based on the calix[4]arene backbone in 1,3-alternate conformation bearing four pyridines acting as hydrogen bond acceptors was achieved and its solid state structure was studied by X-ray diffraction on a single-crystal. In the presence of 4,4'-biphenol 6 acting as di-hydrogen bond donor, compound 1 formed infinite single strand helical 1-D molecular networks which upon lateral association were packed in the crystalline phas e into quintuple helices.

"Synthesis and Structural Analysis of Mercaptothiacalix[4]arene"

P. RAO, M. W. HOSSEINI, A. DE CIAN, J. FISCHER, Chem. Comm., 1999, 2169-2170. (download .pdf)

Abstract : The synthesis of p-tert-butyltetramercaptotetrathiacalix[4]arene 1 bearing 8 sulphur atoms was achieved in high overall yield (80 %). The synthetic strategy used was based on the synthesis of p-tert-butyltetrathiacalix[4]arene 2, treatment of the latter with N,N-dimethylthiacarbamoyl chloride under mild conditions, thermal transposition of the O-thiacarbamoyl into the S-thiacarbamoyl derivatives in quantitative yield and deprotection of the sulphur centres by treatment with hydrazine hydrate. The conformation of compound 1 was investigated in the solid state by X-ray diffraction on a single-crystal, which revealed that compound 1 adopts the 1,3-alternate conformation.

"Self-assembly of a bis bidentate Py2S4 ligand and cadmium cation into 1- and 2-D coordination networks"

M. LOÏ, E. GRAF, M. W. HOSSEINI, A. DE CIAN, J. FISCHER, Chem. Comm., 1999, 603-604. (download .pdf)

Abstract : Using a Py2S4 bis-tridentate ligand and Cd(II), 1- and 2-D coordination networks were obtained and characterised in the solid state. Whereas the 1-D network was obtained using cadmium (II) dichloride salt, the 2-D network was obtained using a mixed chloride and tetrafluoroborate cadmium (II) salt. In the latter case, the inclusion of two CHCl3 molecules within cavities formed by the organic and inorganic fragments was observed.

"Self-assembly of Pyrazolyl Ligands and Silver Cation into Metallamacrocycle and Metallatube"

M. LOÏ, M. W. HOSSEINI, A. JOUAITI, A. DE CIAN, J. FISCHER, Eur. J. Inorg. Chem., 1999, 1981-1985.

Abstract : Using bis- and tris-pyrazolyl ligands based on pyrazine and phenyl rings respectively and Ag+, metallamacrocycles and a metallatube were obtained under self-assembly conditions. Both complexes were characterised by single-crystal X-ray studies.

"Synthesis and Solid State Structural Analysis of Conformers of Tetrakis((ethoxycarbonyl)methoxy)tetrathiacalix[4]arene"

H. AKDAS, G. MISLIN, E. GRAF, M. W. HOSSEINI, A. DE CIAN, J. FISCHER, Tetrahedron Lett., 1999, 40, 2113- 2116.(download .pdf)

Abstract : The role of alkaline metal cations in the synthesis and in determining the conformer distribution of tetrakis((ethoxycarbonyl)methoxy)tetrathiacalix[4]arene obtained by treatment of tetrathiacalix[4]arene 1 in acetone by ethyl bromoacetate in the presence of M2CO3 was systematically investigated. Among the four possible conformers, the cone, partial cone and 1,3-alternate conformers were obtained, purified and structurally characterised by X-ray analysis in the solid state. Although for Li+ no tetra substituted derivative was observed, for Nai+ the cone conformer was exclusively formed while for both Ki+ and Csi+ a mixture of partial cone and 1,3-alternate conformers was obtained.

"Thiacalixarenes as Cluster Keepers : Synthesis and Structural Analysis of a Magnetically Coupled Tetracopper(II) Square"

G. MISLIN, E. GRAF, M. W. HOSSEINI, A. BILYK, A. K. HALL, J. McB HARROWFIELD, B. W. SKELTON, A. H. WHITE, Chem Comm., 1999, 373-374. (download .pdf)

Abstract : An X-ray structure determination of an antiferromagnetic copper complex of p-t-butyl-tetrathiacalix[4]arene has shown it to contain a square, phenoxo- and sulfur-bridged cluster of four Cu(II) ions sandwiched between two fully deprotonated calixarenes, thus forming a ditopic, divergent receptor. As prepared, the complex has each cavity occupied by a molecule of dichloromethane.

"Tetrasulfinylcalix[4]arenes : Synthesis and Solid State Structural Analysis"

G. MISLIN, E. GRAF, M. W. HOSSEINI, A. DE CIAN, J. FISCHER, Tetrahedron Lett., 1999, 40, 1129-1132. (download .pdf)

Abstract : The synthesis of two tetrasulfinylcalix[4]arene was achieved by partial oxidation of tetrathiacalix[4]arene precursors. In both cases, the 1,3-alternate conformation of the calix units and the alternate orientation of the sulfoxide groups were demonstrated by X-ray diffraction studies in the solid state. In the case of tetrasulfinylcalix[4]arene, a 3-D network based on stacking interactions between the aromatic groups was observed.

"Synthesis, Structural, EPR and Magnetic Analysis of Nitronyl-nitroxide labelled Isophthalic acid"

O. FELIX, M. W. HOSSEINI, A. DE CIAN, J. FISCHER, L. CATALA, P. TUREK, Tetrahedron Lett., 1999, 41, 2943-2946.(download .pdf)

Abstract : The high yield synthesis of an isophthalic acid derivative bearing a nitronyl-nitroxide moiety at the 5-position was achieved. The structural analysis in the crystalline phase by X-ray diffraction on single crystals revealed the formation of a 3-D network through strong H-bonds between the acid groups and the nitronyl-nitroxide moieties. The spin label obtained was also analysed by EPR spectroscopy which showed a five line pattern with a N=7.51 G and a g-factor of 2.0066. Magnetic measurements revealed that at low temperature, the systeme showed a Curie-Weiss like behaviour with weak ferromagnetic intermolecular interactions.