We present here a theoretical investigation of the electronic and energetic properties of Na(+)GC, a DNA motif bound to a sodium ion (Na(+)) at the N(7) and O(6) sites of guanine (G), and its hole-trapped derivative [Na(+)GC](+) using density functional theory calculations. Normally, Na(+)GC has positive dissociation energies along various dissociation channels. However, hole-trapping of the Na...

We discuss models for the force-induced dissociation of a ligand-receptor bond, occurring in the context of cell adhesion or single molecule unbinding force measurements. We consider a bond with a structured energy landscape which is modeled by a network of force dependent transition rates between intermediate states. The behavior of a model with only one intermediate state and a model describi...

In this communication, we describe p-xylene oxidation with molecular oxygen at 373 K and atmospheric pressure using N-hydroximide catalysts. p-Xylene conversion was rather high over the first 2 h of reaction and complete by the end of the experiment. The product distribution curves versus reaction time are typical of consecutive reactions. The main intermediate product is p-toluic acid. Peak co...

Schallamach’s theory of rate-dependent bond dissociation is used to understand the fracture of a polymerglass interface. The model system consists of an elastomeric film (20 μm thick) of poly(dimethylsiloxane), chemically bonded to a silanized glass substrate. The fracture energy of the interface varies logarithmically with velocity, which is consistent with Schallamach’s theory of forced bond ...

Ab initio and density functional theory-based computations are performed to investigate the structure and stability of H3SiNgNSi and HSiNgNSi compounds (Ng = Xe, Rn). They are thermochemically unstable with respect to the dissociation channel producing Ng and H3SiNSi or HSiNSi. However, they are kinetically stable with respect to this dissociation channel having activation free energy barriers ...

■ Abstract On laboratory time scales, the energy landscape of a weak bond along a dissociation pathway is fully explored through Brownian-thermal excitations, and energy barriers become encoded in a dissociation time that varies with applied force. Probed with ramps of force over an enormous range of rates (force/time), this kinetic profile is transformed into a dynamic spectrum of bond rupture...

Strong field-induced dissociation by intense mid-infrared pulses was investigated in bromofluoroform monocation (CF3Br(+)) and iodobenzene dication (C6H5I(2+)) using ab initio molecular dynamics calculations. In both systems, bond -selective dissociation was achieved using appropriate laser polarizations and wavelengths. For CF3Br(+), energetically disfavored fluorine elimination was strongly e...

The effect of a homogeneous external electric field parallel to the hydrogen bond in the FH...FH dimer has been studied by theoretical methods. The quantum theory of atoms in molecules methodology has been used for analyzing the electron distribution of the dimer, calculated with different hydrogen bond distances and external field magnitudes. It is shown that an electric field in the opposite ...

We used the density functional theory to evaluate the suitability of nitrenium ions and trivalent boron ligands as analogues of N-heterocyclic carbenes in ruthenium-based metathesis catalysts. We demonstrate that these analogues induce only minor structural changes in Hoveyda-Grubbs-like precatalysts, but have major impact on precatalyst initiation. Nitrenium ion-modified precatalysts are chara...

Photodissociation dynamics of 1,2-dibromopropane has been investigated at 234 and 265 nm by using the velocity map ion imaging method. At both pump energies, a single Gaussian-shaped speed distribution is observed for the Br*((2)P(1/2)) fragment, whereas at least three velocity components are found to be existent for the Br((2)P(3/2)) product. The secondary C-Br bond cleavage of the bromopropyl...