Biomedical subjects

Benedetta Mennucci

Publications and source records attributed to Benedetta Mennucci.

21 records · Page 2Linked to original sources

PubMed2004

Density functional study of the optical rotation of glucose in aqueous solution.

Optical rotation values were calculated for the eight most abundant structures of glucose in aqueous solution, following the TD-DFT/GIAO approach for the property and the PCM description for the solvent. The results show that all alpha structures give a large positive contribution to the OR property, while the beta structures give both positive and negative contributions. The good agreement of the calculated OR, obtained as a Boltzmann average of the property of the eight conformers, with experimental data proves the validity of the quantum-mechanical approach and of the solvent modelization.

Glucose↗

PubMed2004

Excitation energy transfer (EET) between molecules in condensed matter: a novel application of the polarizable continuum model (PCM).

We present a quantum-mechanical theory to study excitation energy transfers between molecular systems in solution. The model is developed within the time-dependent (TD) density-functional theory and the solvent effects are introduced in terms of the polarizable continuum model (PCM). Unique characteristic of this model is that both "reaction field" and screening effects are included in a coherent and self-consistent way. This is obtained by introducing proper solvent-specific operators in the Kohn-Sham equations and in the corresponding TD scheme. The solvation model exploits the integral equation formalism (IEF) version of PCM and it defines the solvent operators on a molecular cavity modeled on the real three-dimensional (3D) structure of the solute systems. Applications to EET in dimers of ethylene and naphtalene are presented and discussed.

Journal Article↗

PubMed2002

Hydrogen bond versus polar effects: an ab initio analysis on n --> pi* absorption spectra and N nuclear shieldings of diazines in solution.

The complex nature of the effect of H-bonding solvents on electronic and magnetic properties of diazines in dilute solution is analyzed by comparing results obtained with continuum, discrete, and mixed continuum-discrete solvation methods. For comparison, other, nonprotic solvents are also considered. The interpretation of the results shows that strong H-bonding effects, such as those exerted by water molecules on diazines nitrogens, are accompanied by comparable (or at least not negligible) long-range polar interactions. It is also shown that a continuum model not only well describes such "bulk effects" but becomes essential to get the correct description of the interactions due to explicit H-bonded molecules. This double action (direct, as an additional long-range field, and indirect, through the H-bonded molecules) significantly modifies the solute electronic and nuclear charge distribution and the related response properties. This picture is confirmed by an NBO analysis on single diazines and the corresponding H-bonded clusters with and without an external continuum solvent.

Journal Article↗