Anibal Sierraalta

Synthesis, characterization and biological activity of trans-platinum(II) complexes with chloroquine

Three platinum-chloroquine complexes, trans-Pt(CQDP)(2)(I)(2) [1], trans-Pt(CQDP)(2)(Cl)(2) [2] and trans-Pt(CQ)(2)(Cl)(2) [3], were prepared and their most probable structure was established through a combination of spectroscopic analysis and density functional theory (DFT) calculations. Their interaction with DNA was studied and their activity against 6 tumor cell lines was evaluated. Compounds 1 and 2 interact with DNA primarily through electrostatic contacts and hydrogen bonding, with a minor contribution of a covalent interaction, while compound 3 binds to DNA predominantly in a covalent fashion, with weaker secondary electrostatic interactions and possibly hydrogen bonding, this complex also exerted greater cytotoxic activity against the tumor cell lines.

ANALYSIS OF PARAMETRIC FUNCTIONALS IN SEMIEMPIRICAL APPROACHES USING SIMULATION TECHNIQUES

Abstract In this work a comparative study of energy functional components of a parametric Hamiltonian ( H pa ) and those obtained from an analytical method is presented. Error cancellations in approximations occur between electronic and nuclear repulsion energies and between attractive and repulsive electronic components of the energy. Parametric functionals associated with the correlation energy are discussed. Some modifications to the studied H pa , mainly in the way of simulating electron repulsion integrals, are tested. Simulation techniques based on binding energy functionals were utilized to parameterize the modified H pa . Preliminary results indicate that important improvements of the total, electronic, and core–core repulsion energies with respect to analytical values can be obtained by modifying the way the electron repulsion integrals in H pa are simulated.

Robust hydrogen-bonded self-assemblies from biimidazole complexes. Synthesis and structural characterization of [M(biimidazole)2(OH2)2]2+ (M = Co2+, Ni2+) complexes and carboxylate modulesElectronic supplementary information (ESI) available: TG/DSC analyses for compound 4. See http://www.rsc.org/suppdata/dt/b3/b312541f/

A robust heteromeric hydrogen-bonded synthon [R2(2) (9)-Id] is exploited to drive the modular self-assembly of four coordination complexes [M(H2biim)2(OH2)2]2+ (M = Co2+, Ni2+) and carboxylate counterions. This strategy allowed us to build molecular architectures of 0-, 1-, and 2-dimensions. A hydrogen-bonded 2D-network with cavities has been designed, which maintains its striking integrity after reversible water desorption-resorption processes.

Model parametric Hamiltonians and bonding theoretical tools in simulation of catalytic reaction steps. Hydrotreatment of oil components

Quantum chemistry calculations of hydrocarbons components and hydrogen have been carried out using model surface adsorption sites on aggregates and model parametric Hamiltonians. Baders topological analysis of the charge density in the valence region is used to describe the adsorption site on which reactions may occur. A description of the adsorbate and surface bindings with diatomic binding energies (DBE) and orbital interactions are presented. Chemisorption and hydrogenation reactions of molecular fragments that are intermediates in hydrocarbon formation on a nickel aggregate were calculated. Also, the growing of hydrocarbon chains and the building of carbonaceous filaments were studied. The modeling of hydrogen dissociation on HDS catalyst was analyzed. In addition, the hydrogenation step of the HDN reaction on a modeled MoS 2 catalyst, employing pyridine as model molecule, is presented.

Modeling MoS2 catalytic surface with simple clusters

Abstract Theoretical calculations using a modified version of CNDO/UHF method to correct binding energies were carried out on a series of linear Mo x S y ( x =3; y =6, 8, 10, 12, 14 and x =5; y =12, 14) and non-linear ( x =3, y =6, 8, and x =5, y =6, 8, 10, 12, 14, 16, 18, 20) clusters. Results show the formation of S 2 − species on the surface and the existence of a Moue5f8Mo interaction. The HOMO orbitals are localized on mono-coordinate S atoms which shows that these atoms have electron-donating properties while the LUMO orbital is delocalized over all coordinatively unsaturated Mo atoms which presents electron-acceptor properties. It is shown that the non-linear clusters are better models for representation of MoS 2 catalysts, because they of their stability respect to the linear clusters.

Chemistry of carbonization—I. A theoretical study of free radical formation from starting materials

Abstract The effect of size, shape, and aromaticity in the formation of radicals from model polyaromatic hydrocarbons (PAH) was theoretically studied using the MINDO/3 method. The results were interpreted in terms of hydrogen transfer on carbonization and liquefaction processes of coal-related compounds. Additives that donate or withdraw electrons were modeled by calculating negatively or positively charged systems. The results show that the hydrogen donating properties of PAHs increase with the increase of their molecular weights. The formation of anionic π-radicals is thermodynamically favored, contrary to cationic π-radicals. Negative charge favored the formation of low molecular weight radicals, and therefore, the hydrogen transfer from light to heavy PAHs. Positive charges, in general, do not facilitate the hydrogen transfer.

Theoretical study of small clusters Au_{5-6} on Au/SAPO-11 catalysts and their interactions with CO

Quantum chemistry calculations were done, using the ONIOM2 methodology at two different levels of calculation, B3LYP for the high level and UFF for the low level. These calculations were performed on Au_{5}/SAPO-11, Au_{6}/SAPO-11, CO-Au_{5}/SAPO-11 and CO-Au_{6}/SAPO-11 aggregates to analyze the geometries of small clusters of Au_{5} and Au_{6} on SAPO-11 support. Au_{5} cluster presents a pentagonal structure in Au_{5}/SAPO-11. Au_{6} aggregate shows a multi triangular structure as from a trapezoidal W shaped Au_{5} in Au_{6}/SAPO-11. Au_{5} is also obtained as an X shaped structure. Similarly another Au_{6} aggregate configuration is obtained also multi triangular but as from X shape Au_{5} cluster. The CO interaction with Au_{5} and Au_{6}/SAPO-11 is studied. The formation energy ΔE_{F} of the aggregates, the CO adsorption energy ΔE_{ads} on them and CO frequency are presented.

Theoretical ONIOM2/DFT study of Pd/ZSM-5 catalyst: CO and NO adsorption

In this study, we carried out two-layer ONIOMDFT:MM calculations to determine the adsorption enthalpies and vibrational frequencies of NO and CO molecules, on palladium exchanged zeolite Pd/ZSM-5 catalyst. The results reveal that the local Al distribution near to Pd^{+2} influence the stretching frequencies as well as the adsorption enthalpies. The nine possible Al distributions studied can be gathered in two groups. One responsible for high CO and NO frequencies e_{CO}= 2146 cm^{-1} and e_{NO}= 1880 cm^{-1} and the other one responsible for the low frequencies e_{CO} = 2127 cm^{-1} and e_{NO}= 1840 cm^{-1}. In general, the adsorption enthalpy of the CO is similar to the NO therefore; there is not a preferential adsorption of CO over the NO molecule.

Theoretical study of substituted methyl mercury in gas phase and in solution

Quantum chemistry calculations were carried out, using density functional theory, in order to investigate the thermodynamic properties, enthalpy (ΔH), Gibbs free energy (ΔG) and equilibrium constant (K

Theoretical study of the water effect on CO adsorbed over Au/SAPO-11 catalysts

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