The simultaneous interactions of an anion and a cation with a π system were investigated by MP2 and M06-2X theoretical calculations. Indole was chosen as a model π system for its relevance in biological environments. Two different orientations of the anion, interacting with the N-H and with the C-H groups of indole, were considered. The four cations (Na(+), NH4(+), C(NH2)3(+) and N(CH3)4(+)) an...

The known solvent dependence of J(Cc,Hf) and J(C1,Hf) couplings in acetaldehyde is studied from a theoretical viewpoint based on the density functional theory approach where the dielectric solvent effect is taken into account with the polarizable continuum model. The four terms of scalar couplings, Fermi contact, paramagnetic spin orbital, diamagnetic spin orbital and spin dipolar, are calculat...

Methylviologen dication is easily reduced to a monocation radical, and turned to be blue, forming a charge-transfer complex with a donor molecule. Yoshikawa et al. recently reported photo-induced reduction and charge transfer complexes in polycyano–polycadmate host clathrates. We study this reduction using quantum chemical calculations. The energy changes with the torsion angle of the two catio...

We focus on molecular cavities which are represented in the form of Solvent Excluded Surfaces. They are featured by having smooth toroidal and spherical surface blendings between the constituting atoms. The only inputs are the nuclear coordinates, the van der Waals radii and the probe radius. From those information, our purpose is to generate a patch representation of the resulting Connolly sur...

The present mini-review aims first at an introduction to two thermodynamic essentials of the binding between the influenza A virus hemagglutinin (HA) and the cell surface receptor sialoside, (1) the equilibrium 1:1 binding of the HA with the sialoside, (2) the polyvalent effect of the HA binding to the polyvalent sialoside. Second, the review introduces the fragment molecular orbital (FMO) stud...

Oxindole derivatives which are commercially available have got antiviral, antifungal, antibacterial, anticancer, anti-inflammatory, antihypertensive, and anticonvulsant activities. The solvation analysis of oxindole derivatives has been carried out using B3LYP procedure with 6-311++G basis set using ten solvents to compute the electrostatic interaction, repulsive, dispersive energy and cavitati...

The simplicity of dielectric continuum models has made them a standard tool in almost any Quantum Chemistry (QC) package. Despite being intuitive from a physical point of view, the actual electrostatic problem at the cavity boundary is challenging: the underlying boundary integral equations depend on singular, long-range operators. The parametrization of the cavity boundary should be molecular-...

Geometry optimizations of all cluster models were carried out in solution with Integral Equation Formalism Polarizable Continuum Model (IEFPCM) as implemented in Gaussian09. The B3LYP functional in conjunction with the 6-31+g(d) basis set was employed to optimize the geometries. Frequency calculations at the same level of theory were carried out to verify the nature of the stationary points enc...