Biomedical subjects

Elisabetta Mezzina

Publications and source records attributed to Elisabetta Mezzina.

3 recordsLinked to original sources

PubMed2006

Synthesis and characterization of a persistent paramagnetic rotaxane based on alpha-cyclodextrin.

The synthesis and spectroscopic properties of a novel paramagnetic [2]rotaxane is described. This rotaxane is made from molecules having an alkyl chain flanked by 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) groups. Complexation of sebacoyl chloride by alpha-cyclodextrin followed by reaction with a bulky aminonitroxide resulted in the trapping of the cyclodextrin, threaded by the alkyl chain, thus generating the rotaxane structure. The structure of the paramagnetic [2]rotaxane was fully characterized by ESI-MS, 1D and 2D NMR and ESR spectroscopy.

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PubMed2004

Combining magnetic resonance spectroscopies, mass spectrometry, and molecular dynamics: investigation of chiral recognition by 2,6-di-O-methyl-beta-cyclodextrin.

EPR spectroscopy has been employed to investigate the formation of complexes between heptakis-(2,6-O-dimethyl)-beta-cyclodextrin (DM-beta-CD) and different enantiomeric pairs of chiral nitroxides of general structure PhCH2NO.CH(R)R'. Accurate equilibrium measurements of the concentrations of free and included radicals afforded the binding constant values for these nitroxides. The relationship between the stereochemistry of the DM-beta-CD complexes and the thermodynamics of complexation was elucidated by correlating EPR data with 1H-1H NOE measurements carried out on the complexes between DM-beta-CD and the structurally related amine precursors of nitroxides. NOE data suggested that inclusion of the stereogenic center in the DM-beta-CD cavity occurs only when the R substituent linked to the chiral carbon contains an aromatic ring. For these types of complexes, molecular dynamics simulation indicated that the depth of penetration of the stereogenic center into the cyclodextrin cavity is determined by the nature of the second substituent (R') at the asymmetric carbon and is responsible for the observed chiral selectivity. Analysis of mass spectra showed that, for the presently investigated amines, electrostatic external adducts of CDs with protonated amines are detected by ESI-MS.

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PubMed2002

Gel-like lyomesophases formed in organic solvents by self-assembled guanine ribbons.

Lipophilic guanosine derivatives are self-assembled into ribbonlike aggregates, both in the crystal state and in solution. The structure of the ribbons has been characterised by single-crystal X-ray diffraction and, in solution, by NMR spectroscopy and ESI-MS. Two different ribbons with different patterns of hydrogen bonds are present in the solid state and in chloroform solutions. The gel-like phases obtained in hexadecane, toluene and chloroform have been investigated by optical microscopy and small-angle X-ray diffraction: the type of phase observed is related to the molecular structure of the compounds and depends dramatically on the solvent. The structures of the phases are discussed, with the presence of the two different ribbons being taken into account.

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