We have presented a detailed theoretical (density functional theory and ONIOM) study on the structure and M-PrP (prion protein) interaction on various prion models, M(PrP) systems (where PrP = HGG, HGGGW x 3H(2)O, and PrP(61-84), and M = Zn, Cu, Ni, Co, Fe, Mn). It was shown that the geometry of the complex [Mn(HGGGW)(H(2)O)] x 2H(2)O is quite different for M = Mn(III) and Mn(II), and partial u...

Photosystem II (PSII) of photosynthesis has the unique ability to photochemically oxidize water. Recently an engineered bacterioferritin photochemical 'reaction centre' (BFR-RC) using a zinc chlorin pigment (ZnCe6) in place of its native heme has been shown to photo-oxidize bound manganese ions through a tyrosine residue, thus mimicking two of the key reactions on the electron donor side of PSI...

Renewable production of p-xylene from [4 + 2] Diels− Alder cycloaddition of 2,5-dimethylfuran (DMF) and ethylene with H−Y zeolite catalyst in n-heptane solvent is investigated. Experimental studies varying the solid acid catalyst concentration reveal two kinetic regimes for the p-xylene production rate: (i) a linear regime at low acid site concentrations with activation energy Ea = 10.8 kcal/mo...

2,6-Dimethylnaphthalene (DMN) is the key intermediate in the synthesis of poly(ethylene naphthalate) (PEN), a high-performance polymer. The detailed reaction mechanism of the catalyzed 1,5to 2,6DMN isomerization via 1,6-DMN by acidic beta zeolite is investigated at the ONIOM(M06-L/6-31G(d,p):UFF) level of theory. The M06-L method, a newly developed density functional theory, is applied for the ...

Doxorubicin is a chemotherapeutic drug used as a cure for cancer. Being an anthracycline antibiotic, it is commonly used in treating a wide varieties of cancers. In this report, the molecular structure, Binding Energy(BE), Dipole Moment (DM), Gibbs free energy of solvation (ΔG(solvation)) and some physicochemical properties of Doxorubicin were conjugated chemically to the terminal end of a di-b...

In this work, we present a simple approach to simulate absorption spectra from hybrid QM/QM calculations. The goal is to obtain reliable spectra for compounds that are too large to be treated efficiently at a high level of theory. The present approach is based on the extrapolation of the entire absorption spectrum obtained by individual subcalculations. Our program locates the main spectral fea...

The ring-shift isomerization of sym-octahydrophenanthrene (sym-OHP) to sym-octahydroanthracene (sym-OHA) catalyzed by acidic zeolites (Mordenite (MOR) and Faujasite (FAU)) was investigated by the ONIOM(DFT:UFF) and DFT approaches. A "five-membered ring" mechanism through carbocation rearrangement via 1-2 migration was proved to be kinetically favored over a "six-membered ring" mechanism through...

Free energies for the homolysis of the NO-C and N-OC bonds were compared for a large number of alkoxyamines at 298 and 393 K, both in the gas phase and in toluene solution. On this basis, the scope of the N-OC homolysis side reaction in nitroxide-mediated polymerization was determined. It was found that the free energies of NO-C and N-OC homolysis are not correlated, with NO-C homolysis being m...

0021-9517/$ see front matter 2009 Elsevier Inc. A doi:10.1016/j.jcat.2009.10.015 * Corresponding author. Address: Goesmann 222, Amherst, MA 01003-9336, USA. Fax: +1 413 545 4490 E-mail addresses: [email protected] (V. Ag (G.W. Huber), [email protected] (W.C. Conner edu (S.M. Auerbach). We have performed embedded-cluster calculations using density functional theory to investigate mechan...