Mechanism of the Formation of Palladium(II) Maleate Complex: A DFT Approach

Mechanistic and energetic studies of superparamagnetic iron oxide nanoparticles as a cyclophosphamide anticancer drug nanocarrier: A quantum mechanical approach

Using Fe6(OH)18(H2O)6 as a ring cluster model for superparamagnetic iron oxide nanoparticles, noncovalent configurations and three mechanisms of covalent functionalization of superparamagnetic iron oxide nanoparticles with cyclophosphamide an anticancer drug were studied. Quantum molecular descriptors, solvation, and binding energies of noncovalent interactions were investigated the in gas and solution phases at the B3LYP and M06-2X density functional levels. In the vicinity of superparamagnetic iron oxide nanoparticles, the reactivity of the drug increases, showing cyclophosphamide can probably bind to superparamagnetic iron oxide nanoparticles through Cl ( k1 mechanism), P=O ( k2 mechanism), and NH in a six-membered ring ( k3 mechanism) groups. The activation parameters of all pathways were calculated, indicating the high barriers related to the k1 and k2 mechanisms are higher the barrier related to the k3 mechanism. The k3 mechanism is also spontaneous and exothermic and is therefore the preferred mechanism for covalent functionalization.

Quantum Mechanical Study of γ-Fe2O3 Nanoparticle as a Nanocarrier for Anticancer Drug Delivery

Using density functional theory (DFT), noncovalent interactions and four mechanisms of covalent functionalization of melphalan anticancer drug onto γ-Fe2O3 nanoparticles have been studied. Quantum molecular descriptors of noncovalent configurations were investigated. It was specified that binding of melphalan onto γ-Fe2O3 nanoparticles is thermodynamically suitable. Hardness and the gap of energy between LUMO and HOMO of melphalan are higher than the noncovalent configurations, showing the reactivity of drug increases in the presence of γ-Fe2O3 nanoparticles. Melphalan can bond to γ-Fe2O3 nanoparticles through NH2 (k 1 mechanism), OH (k 2 mechanism), C=O (k 3 mechanism) and Cl (k 4 mechanism) groups. The activation energies, the activation enthalpies and the activation Gibbs free energies of these reactions were calculated. Thermodynamic data indicate that k 3 mechanism is exothermic and spontaneous and can take place at room temperature. These results could be generalized to other similar drugs.

Density Functional Theoretical Study on the Mechanism of Alcoholysis of Acylpalladium(II) Complexes

The mechanism of alcoholysis of acylpalladium(II) complexes relevant to the alternating copolymerisation of ethene and carbon monoxide has been investigated theoretically in detail. The solvolysis of acylpalladium(II) complexes is an important step in palladium-catalysed reactions. Based on experimental studies, two mechanisms have been proposed for this process, which consist of a concerted reductive elimination and an insertion mechanism (reductive elimination via a Meisenheimer intermediate). Both mechanisms include deprotonating of an acylpalladium(II) complex and according to our calculations, any mechanism involving this step, has an energy barrier higher than that of the rate-determining step. We propose a new mechanism for the insertion in which proton transfer to Pd is simultaneous with an inner-sphere attack of the alkoxide ligand (OCH3) at the carbon atom of the palladium-bound carbonyl group (new Meisenheimer intermediate). Considering solvent effects, the activation energies of the two mechanisms and other contingent mechanisms were calculated and compared with each other and the experimental results.

Theoretical Study on the Mechanism of Covalent Bonding of Dapsone onto Functionalised Carbon Nanotubes: Effects of Coupling Agent

Using density functional theory, two mechanisms of covalent bonding of dapsone onto functionalised carbon nanotubes have been investigated, the first one being direct bonding and the second one being bonding by using coupling agents. In this work, the mechanism of functioning of an important coupling agent (1-[bis(dimethylamino)methylene]-1H-1,2,3-triazolo [4,5-b]pyridinium 3-oxide hexafluorophosphate, N-HATU) has been investigated. The activation energy and activation Gibbs free energy of the two pathways have been calculated and compared with each other. It was found that using the coupling agents will reduce the energy barrier. All of the calculations have been performed in the solution phase (polarised continuum model) using the B3YLP hybrid density functional.

Quantum mechanical investigation on the hydroxycarbonylation of styrene using a palladium complex catalyst

Here we have investigated the kinetics and mechanism of [Pd(pyca)(PPh3)(OTS)/PPh3/TSOH/LiCl] system-catalysed hydroxycarbonylation of styrene using density functional theory (DFT). A new mechanism is proposed in which there is an unoccupied coordination position on the Pd. In the final step, this provides the necessary conditions for an attack of the coordinated H2O on the acyl moiety, resulting in production of the final product. The proposed mechanism consists of three main steps. The final step, the formation of the products, is rate-determining. The DFT results are in good agreement with experiment.

Mechanism of covalent adsorption of benzenesulfonamide onto COOH– and COCl– functionalised carbon nanotubes

Using density functional theory, two mechanisms of covalent adsorption of benzenesulfonamide in water in the presence of functionalised carbon nanotubes were investigated. COOH– and COCl–functionalised carbon nanotubes can bond to the benzenesulfonamide via OH (OH pathway) and Cl (Cl pathway) groups, respectively. The activation energy and activation Gibbs free energy of the two pathways have been calculated and compared with each other. It was found that the OH pathway has an energy barrier higher than the Cl pathway and, in contrast to the Cl pathway, product formation is endothermic and non-spontaneous, being thus the reason for the dominance of the Cl pathway. All the calculations were performed using a hybrid density functional method (B3LYP) in the solution phase (polarised continuum model or PCM).

Recent application of calculations of metal complexes based on density functional theory

Recent application of density functional theory (DFT) for metal complexes is reviewed to show the achievements of DFT and the challenges for it, as well as the methods for selecting proper functionals.