Maria Montagna

Theoretical study of ionic liquids based on the cholinium cation. Ab initio simulations of their condensed phases

We have explored by means of ab initio molecular dynamics the homologue series of 11 different ionic liquids based on the combination of the cholinium cation with deprotonated amino acid anions. We present a structural analysis of the liquid states of these compounds as revealed by accurate ab initio computations of the forces. We highlight the persistent structural motifs that see the ionic couple as the basic building block of the liquid whereby a strong hydrogen bonding network substantially determines the short range structural behavior of the bulk state. Other minor docking features of the interaction network are also discovered and described. Special cases along the series such as Cysteine and Phenylalanine are discussed in the view of their peculiar properties due to zwitterion formation and additional long-range structural organization.

Spectroscopic evidence for a gas-phase librating G-quartet–Na+ complex

The IRMPD spectrum of the G-quartet-Na(+) complex, in combination with an ab initio molecular dynamic simulation, revealed the presence of two metastable populations of conformers separated by a free energy barrier easily accessible at room temperature.

Structure, Stability, and Electronic Properties of Dimethyl Sulfoxide and Dimethyl Formammide Clusters Containing Th(4.).

By using accurate density functional theory calculations, we have studied the complexes of Th(4+) with dimethyl-sulfoxide (DMSO) and dimethyl-formammide (DMF) molecules. These solvents are prototypes for oxygen-donor organic environments in which the oxygen atom is connected to S and C atom, respectively. Extended structural, energetic, and electronic structure analysis has been performed to provide a complete picture of the physical properties at the basis of the interaction of Th(4+) with the two solvents. By using a cluster grow approach, we have found that, very likely, the first solvation shell contains nine molecules in the case of DMSO, while it contains eight molecules for DMF. The theoretical results shown here are in agreement with experimental data taken from the literature.

Contact Ion Pairs on a Protonated Azamacrocycle: the Role of the Anion Basicity.

AbstractA potassium-containing hexaazamacrocyclic dication, [M•H•K]2+, is able to add in the gas phase mono- and dicarboxylate anions as well as inorganic anions by forming the corresponding monocharged adducts, the structure of which markedly depends on the basicity of the anion. With anions, such as acetate or fluoride, the neutral hexaazamacrocycle M acts as an acceptor of monosolvated K+ ion. With less basic anions, such as trifluoroacetate or chloride, the protonated hexaazamacrocycle [M•H]+ performs the unusual functions of an acceptor of contact K+/anion pairs. Graphical Abstractᅟ

Solvation Properties of the Actinide Ion Th(IV) in DMSO and DMSO:Water Mixtures through Polarizable Molecular Dynamics

We have studied the solvation of Th4+ in water, in dimethyl sulfoxide (DMSO), and in their equimolar mixture by using molecular dynamics based on an Amoeba-derived polarizable force field. We have performed an extended structural analysis in order to provide a complete picture of the chemical-physical features of the interaction of Th4+ with the two solvents in their pure and mixed states. Through our simulations we found that, very likely, the first solvation shell in DMSO is not unlike the one found in pure water and contains 9 solvent molecules. The residence time of first shell of DMSO molecules is however much longer than the residence time of water. For the 1:1 mixture we present computational evidence that both water and DMSO participate in the solvation of Th4+ with a slight preference for the latter.