Biomedical subjects

S Piccirillo

Publications and source records attributed to S Piccirillo.

5 recordsLinked to original sources

PubMed2006

Modelling neurotransmitter functions: a laser spectroscopic study of (1S,2S)-N-methyl pseudoephedrine and its complexes with achiral and chiral molecules.

Wavelength and mass resolved resonance-enhanced two photon ionization (R2PI) excitation spectra of (1S,2S)-N-methyl pseudoephedrine (MPE) and its complexes with several achiral and chiral solvent molecules, including water (W), methyl (R)-lactate (L(R)), methyl (S)-lactate (L(S)), (R)-2-butanol (B(R)), and (S)-2-butanol (B(S)), have been recorded after a supersonic molecular beam expansion and examined in the light of ab initio calculations. The spectral patterns of the selected complexes have been interpreted in terms of the specific hydrogen-bond interactions operating in the diastereomeric complexes, whose nature in turn depends on the structure and the configuration of the solvent molecule. The obtained results confirm the view that a representative neurotransmitter molecule, like MPE, "communicates" with the enantiomers of a chiral substrate through different, specific interactions. These findings can be regarded as a further contribution to modelling neurotransmitter functions in biological systems.

Butanols↗

PubMed2005

Chiral clusters in a supersonic beam: R2PI-TOF spectroscopy of diastereomeric carboxylic esters/(R)-(+)-1-phenyl-1-propanol complexes.

Wavelength and mass resolved resonance-enhanced two photon ionization (R2PI) excitation spectra of (R)-(+)-1-phenyl-1-propanol (P(R)) and its complexes with some chiral esters, i.e. methyl lactates (L(R) and L(S)), methyl 3-hydroxybutyrates (H(R) and H(S)), and methyl 2-chloropropionates (C(R) and C(S)), have been recorded after a supersonic molecular beam expansion and interpreted in the light of DFT calculations. The spectral features of the selected complexes were found to depend on the nature of hydrogen-bond interactions within the diasteromeric complexes, whose intensity in turn depends upon the structure and the configuration of the estereal moiety. The study further confirms resonant two-photon ionization spectroscopy, coupled with time-of-flight mass resolution (R2PI-TOF), as an excellent tool for gathering valuable information on the interactive forces in molecular clusters and for the enantiodiscrimination of chiral molecules in the gas phase.

Esters↗

PubMed2002

Chiral discrimination of 2,3-butanediols by laser spectroscopy.

The resonance enhanced two-photon ionization time-of-flight (R2PI-TOF) excitation spectra of supersonically expanded complexes of isomeric 2,3-butanediols with a suitable chromophore, i.e. R-(+)-1-phenyl-1-propanol, represent powerful means for structurally discriminating the diol moiety and for investigating the nature of the intra- and intermolecular interactions involved in the complexes.

Journal Article↗

PubMed2001

R2PI Study of intermolecular hydrogen bond in solvent-free chiral complexes.

One- and two-color, mass selected R2PI spectra of the S(1)<--S(0) transitions in the bare (+)-(R)-1-phenyl-1-ethanol (E(R)) and its complexes with different solvent molecules (solv) (-)-(R)-2-butanol (B(R)) or (+)-(S)-2-butanol (B(S)) and (-)-(R)-2-butylamine (A(R)) or (+)-(S)-2-butylamine (A(S)), have been recorded after a supersonic molecular beam expansion. The one-color R2PI excitation spectra of the diastereomeric complexes are characterized by significant shifts of their band origin relative to that of bare E(R). The extent and the direction of these spectral shifts are found to depend on the structure and the configuration of solv and are attributed to different short-range interactions in the ground and excited states of the complexes. In analogy with other diastereomeric complexes, the phenomenological binding energy of the homochiral cluster is found to be greater than that of the heterochiral one.

Journal Article↗

PubMed2000

Short-range interactions within molecular complexes formed in supersonic beams: structural effects and chiral discrimination

One- and two-color, mass-selected R2PI spectra of the S1<--S0 transitions in the bare chiral chromophore R-(+)-1-phenyl-1-propanol (R) and its complexes with a variety of alcoholic solvent molecules (solv), namely methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, S-(+)-2-butanol, R-(-)-2-butanol, 1-pentanol, S-(+)-2-pentanol, R-(-)-2-pentanol, and 3-pentanol, were recorded after a supersonic molecular beam expansion. Spectral analysis, coupled with theoretical calculations, indicate that several hydrogen-bonded [R.solv] conformers are present in the beam. The R2PI excitation spectra of [R.solv] are characterized by significant shifts of their band origin relative to that of bare R. The extent and direction of these spectral shifts depend on the structure and configuration of solv and are attributed to different short-range interactions in the ground and excited [R.solv] complexes. Measurement of the binding energies of [R.solv] in their neutral and ionic states points to a subtle balance between attractive (electrostatic and dispersive) and repulsive (steric) forces, which control the spectral features of the complexes and allow enantiomeric discrimination of chiral solv molecules.

Journal Article↗