Biomedical subjects

Roberta Pinalli

Publications and source records attributed to Roberta Pinalli.

4 recordsLinked to original sources

PubMed2005

Dynamic and structural NMR studies of cavitand-based coordination cages.

The interionic structure, kinetic stability, and degree of anion encapsulation of coordination cages 1 were studied by PGSE, NOE, and EXSY NMR techniques. The rate constants for the formation/dissociation processes at 296 K were obtained independently via (1)H-NOESY and (19)F-NOESY experiments giving, respectively, k(obs) = 0.30 +/- 0.04 s(-1) in CDCl(3) and k(obs) = 5.2 +/- 0.8 s(-1) in CD(3)NO(2)/CDC(13) (7.1) mixture with the proton probe, and k(obs) = 0.33 +/- 0.06 s(-1) in CDCl(3) and k(obs) = 5.0 +/- 0.8 s(-1) in CD(3)NO(2)/CDC(13) (7/1 mixture) with the (19)F probe. PGSE experiments showed that in CDCl(3) not only the encapsuled anion but also the external anions translate with the same rate as the cage. (19)F,(1)H-HOESY experiments indicated that an average of five external triflate anions are located in the equatorial sites close to the palladium moieties, while two of them approach the polar pockets formed by the alkyl chains. In a CD(3)NO(2)/CDCl(3) (7/1) mixture only one or two anions are in close proximity with the cage, while the others are solvated. In all the considered solvents (benzene, chloroform, methylene chloride, and nitromethane) the inclusion of a single unsolvated triflate anion in the cage is quantitative. (19)F,(1)H-HOESY experiments indicated that the charged guest head points toward one metal center. Therefore, while the ionic aggregation level and kinetic stability of coordination cages 1 are solvent dependent, anion encapsulation is not.

Journal Article↗

PubMed2004

Cavitand-based nanoscale coordination cages.

This communication reports design, self-assembly, solution, and solid-state characterization of nanoscale coordination cages formed by tetradentate cavitand ligands and appropriate metal precursors. The preorganization of the cavitand ligand in terms of structural rigidity and relative orientation of the pyridyl units leads to the exclusive formation of coordination cages in a wide temperature and concentration range. Desired features of the cage self-assembly process, such as reversibility in the presence of a competitive ligand and self-recognition of the cavitand components, have been assessed.

Journal Article↗

PubMed2004

Surface-confined single molecules: assembly and disassembly of nanosize coordination cages on gold (111).

A cavitand functionalized with four alkylthioether groups at the lower rim, and four tolylpyridine groups on the upper rim is able to bind to a gold surface by its thioether groups, and forms a coordination cage with [Pd(dppp)(CF(3)SO(3))(2)] by its pyridine groups. The cavitand or the cage complex can be inserted from solution into a self-assembled monolayer (SAM) of 11-mercaptoundecanol on gold. The inserted molecules can be individually detected as they protrude from the SAM by atomic force microscopy (AFM). The cages can be reversibly assembled and disassembled on the gold surface. AFM can distinguish between single cavitand and cage molecules of 2.5 nm and 5.8 nm height, respectively.

Journal Article↗

PubMed2003

Investigation of the origin of selectivity in cavitand-based supramolecular sensors.

The sensing properties of functionalized cavitands have been studied by thin-film coating TMSR chemical sensors and by measuring their responses towards model analytes. We studied the relationship between the sensor performance, in terms of sensitivity and selectivity, and the molecular recognition properties of the cavitands. The Langmuir-like shape of the adsorption isotherm, obtained in the case of short-chain alcohols, demonstrated that selective binding can be achieved by the synergistic interactions of the cavity and the bridging PO(in) groups. In the absence of these substituents, the peripheral alkyl chains necessary for the formation of highly permeable thin films attenuate the cavity effect because of nonspecific dispersion interactions. This completely overrides the response originating from molecular recognition. The same effect is observed when the PO groups are oriented outward from the cavity. The use of multivariate chemometrics and the study of the correlations between sensors sensitivity and analyte properties provided further evidence of molecular recognition phenomena, whose intensity is enhanced by the permanent free volume created by the rigid cavity surrounding the PO(in) group.

2-Propanol↗