proton transfer (pt) and methyl group transfer (mgt) occurring in small biomimetic systems, formamide-formamidic acid (fa-fi), and n-formyl-n-methylformamide-(e)-methyl n-formylformimidate (nmfa-nmfi) are investigated in the gas phase and in single-walled carbon nanotubes by using the density functional theory and the oniom approach. it is shown that pt reaction is disfavoured in single-walled ...

DFT periodic, ONIOM, and cluster studies with all-electron basis sets are applied to Cu(I) exchanged zeolites and silicoalumino-phosphate analogs with faujasite and chabazite topology. The reactivity of the cations at different cation positions is probed by NO adsorption. In the ONIOM approach, the cation center and the nearest framework environment are described by DFT, whereas a larger part o...

The performance of ONIOM(DFT:MM) methods on the structural description of molecules where intramolecular non-covalent interactions play a critical role is examined systematically and compared with that of full DFT methods, both with and without explicit dispersion corrections. The more detailed study is carried out on dithienobicyclo-[4.4.1]-undeca-3,8-diene-11-one ethylene glycol ketal molecul...

The structure of zeolite clinoptilolite and the coordination of extraframework cations (Ca, Ba, Na and K) by framework oxygen atoms are examined by density functional theory (DFT) using two methods: the ONIOM two-layer model (DFT/MM) and periodic DFT. Both ONIOM and periodic model calculations predict correctly the clinoptilolite structure and find configurations with Al ? Si substitution at th...

Submit Manuscript | http://medcraveonline.com Abbreviations: DOPA: 3,4-Dihydroxy Phenylalanine; MAPs: Mussel Adhesive Proteins; QM: Quantum Mechanics; MM: Molecular Mechanics; PEG: Polyethylene Glycol; LAMBA: Light Activated Mussel-based Bio Adhesive; DFT: Density Functional Theory; EPR: Electron Paramagnetic Resonance; DCTA: DoubleCrosslinked Tissue Adhesives; UFF: Universal Force Field; ONIOM...

The study of the photophysical properties of dendritic-like phosphinothiolate gold(I) complexes has been carried out. The studied complexes are two series of analogous compounds bearing 4 or 8 metal centers: the tetranuclear [Au(4)(S-C(6)H(4)-X)(4){DAB-G0-(PPh(2))(4)}] (X = F (3), MeO (4), Me (5) and NO(2) (6)) and the octanuclear [Au(8)(S-C(6)H(4)-X)(8){DAB-G1-(PPh(2))(8)}] (X = F (9), MeO (10...

The maleate isomerase (MI) catalysed isomerization of maleate to fumarate has been investigated using a wide range of computational modelling techniques, including small model DFT calculations, QM-cluster approach, quantum mechanical/molecular mechanical approach (QM/MM in the ONIOM formalism) and molecular dynamics simulations. Several fundamental questions regarding the mechanism were answere...

The performance of a variety of DFT functionals (BLYP, PBE, B3LYP, B3P86, KMLYP, B1B95, MPWPW91, MPW1B95, BB1K, MPW1K, MPWB1K, and BMK), together with the ab initio methods RHF, RMP2, and G3(MP2)-RAD, and with ONIOM methods based on combinations of these procedures, is examined for calculating the enthalpies of a range of radical reactions. The systems studied include the bond dissociation ener...

The 1,3-dipolar cycloaddition between glycine-derived azlactones with maleimides is efficiently catalyzed by the dimeric chiral complex [(S a)-Binap·AuTFA]2. The alanine-derived oxazolone only reacts with tert-butyl acrylate giving anomalous regiochemistry, which is explained and supported by Natural Resonance Theory and Nucleus Independent Chemical Shifts calculations. The origin of the high e...

The enantioselective alkylation of aldehydes catalysed by nickel(ii)-complexes derived from α-amino amides was studied by means of density functional theory (DFT) and ONIOM (B3LYP:UFF) calculations. A mechanism was proposed in order to investigate the origin of enantioselectivity. The chirality-determining step for the alkylation was the formation of the intermediate complexes with the involvem...