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Estudo teórico da interação de benzbromarona (BZB) com 'beta'-ciclodextrinaßß / Theoretical study of the interaction between benzbromarone (BZB) and 'beta'-ciclodextrinSousa, Iran da Luz, 1989- 27 August 2018 (has links)
Orientador: Nelson Henrique Morgon / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-27T06:46:42Z (GMT). No. of bitstreams: 1
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Previous issue date: 2015 / Resumo: Por apresentar basicamente fórmulas, o Resumo, na íntegra, poderá ser visualizado no texto completo da tese digital / Abstract: The complete Abstract is available with the full electronic document / Mestrado / Físico-Química / Mestre em Química
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Simulação computacional de materiais porosos utilizados na remoção de compostos sulfurados em combustíveisde Paula Santos, Diego 31 January 2010 (has links)
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Previous issue date: 2010 / Faculdade de Amparo à Ciência e Tecnologia do Estado de Pernambuco / As isotermas, estruturas e energias de adsorção de compostos sulfurados aromáticos (tiofeno) e alifáticos (propanotiol) em zeólitas do tipo faujasita na presença de quatro cátions de compensação de carga Na+, H+, Ag+, Cu+ foram estudados com métodos de química quântica e de simulação computacional.
Observamos que as energias de adsorção estão em ótimo acordo com os resultados experimentais e computacionais para o tiofeno e crescem em função do metal na seguinte ordem H+ < Na+ < Ag+ ≈ Cu+. Para o propanotiol a seqüencia da energia de adsorção é a mesma e os resultados são reportados pela primeira vez.
Propusemos dois novos modelos de agregados para representar a zeólita, Z40 e 2Cages. Tais modelos são capazes de explicar diferenças nas energias de adsorção baseadas nas diferentes estruturas obtidas para os complexos de adsorção. Os resultados foram obtidos com o método ONIOM (PBE1PBE/6-31G(d, p): UFF=QEQ) e para os metais de transição ONIOM (PBE1PBE/SDD: UFF=QEQ).
As isotermas de adsorção de tiofeno em diferentes temperaturas nas zeólitas MY (M = Na+, H+ e Ag+) estão em boa concordância com os resultados experimentais e apresentam resultados semi-quantitativos do perfil e ponto de saturação das isotermas, sem a necessidade de ajustes das cargas para valores pouco usuais. Estes resultados foram obtidos utilizando o método de Monte Carlo no ensemble Grã Canônico. Também para a adsorção do propanotiol os resultados são originais
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Ab Initio Molecular Dynamics Simulation of Proton Transfer in Imidazole: An Atom-Centered Density Matrix Propagation (ADMP) ApproachChen, Chi-Yuan 03 April 2006 (has links)
No description available.
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Estudo da adsorção de tiofeno e propanotiol em zeólitas MY (M=H+, Na+, Ag+, Cu+ e Zn2+) com métodos híbridos de química computacionalOLIVEIRA, Paulo McMiller Crisostomo de 23 August 2013 (has links)
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Previous issue date: 2013-08-23 / FACEPE / A adsorção de compostos organossulfurados está se tornando um processo
importante na remoção de enxofre de combustíveis derivados de petróleo. Neste
contexto, realizamos modelagem molecular com método de química
computacional da adsorção de compostos orgânicos sulfurados alifáticos
(propanotiol) e aromáticos (tiofeno) em zeólita Y com os cátions de compensação
de carga H+, Na+, Ag+, Cu+ e Zn2+. As estruturas e as energias de adsorção foram
obtidas com cálculos de química quântica empregando o método ONIOM com
três (PBE1PBE:HF:UFF=QEQ) e duas (PBE1PBE:UFF=QEQ) camadas,
respectivamente, para simular a contribuição do ambiente químico da estrutura
cristalina com um modelo extenso contendo 1473 átomos, denominado, Z40-nT,
com n = 3, 5, 6, 7 e 12 sendo o número de tetraedros SiO4 e AlO4 utilizados nas
vizinhanças da adsorção. Constatou-se que as estruturas obtidas possuem boa
concordância entre si e que fornecem os modos de interação entre o composto
sulfurado e a zeólita. No caso do tiofeno, o modo de coordenação η1S, apesar
de ser menos estável, em que o enxofre do anel interage diretamente cátion foi
aquele que forneceu os melhores resultados com relação aos valores das
energias de adsorção. Disso advém a suposição de que há uma preferência
maior por esse modo de adsorção num sistema real. As zeólitas estudadas
demonstraram alta capacidade de interação com os compostos sulfurados,
justificando assim a potencialidade do uso desses materiais no processo de
dessulfurização adsortiva de combustíveis derivados do petróleo. Para a
adsorção do tiofeno os valores da energia de adsorção crescem em função do
cátion na ordem: H+ < Na+ < Ag+ < Cu+ < Zn2+, para o sítio de adsorção SIII. No
sítio SII as interações com os cátions dos metais de transição são similares.
Estes resultados estão de acordo com o que é observado dos dados
experimentais disponíveis. Para adsorção de propanotiol obtivemos a ordem Na+
< H+ < Ag+ < Cu+ < Zn2+ e esses resultados são inéditos na literatura. / The adsorption of organosulfur compounds is becoming an important process in
desulfurization of fossil fuels. In this context, we performed molecular modeling,
through computational chemistry method, the adsorption of aliphatic
(propanethiol) and aromatic (thiophene) organosulfur compounds in faujasites
zeolites (Y) with four compensation charges: H+, Na+, Ag+, Cu+ and Zn2+. The
structures and adsorption energies were obtained by quantum chemical
calculations employing ONIOM with three (PBE1PBE:HF:UFF=QEQ) and two
(PBE1PBE:UFF=QEQ) layers, respectively, to simulate the chemical
environment contribution of the crystalline structure with a model containing 1473
atoms called Z40-nT, where n = 3, 5, 6, 7 and 12 is the number of tetrahedral
SiO4 and AlO4 used in the site of adsorption. It was found that the structures
obtained showed good agreement between themselves and provide the modes
of interaction between the sulfur compound and the zeolite. For the thiophene,
the coordination mode η1S, although less stable, wherein the sulfur ring interacts
directly with the cation, was that which gave the best results for the values of the
adsorption energies. Thus it comes the assumption of that coordination mode has
a higher preference for adsorption in a real system. Zeolites studied showed a
high capacity for interaction with sulfur compounds, thus justifying the potential
use of these materials in the adsorptive desulfurization of petroleum fuels. For
thiophene, the adsorption energy values, according to the cation, grow in order:
H+ < Na+ < Ag+ < Cu+ < Zn2+ for the adsorption site SIII. On the site SII,
interactions with cations of transition metals are similar. These results are
consistent in good quantitative agreement with the available experimental data.
For adsorption of propanethiol we obtained the order Na+ < H+ < Ag+ < Cu+ < Zn2+
and these results are unpublished in the literature.
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QM/MM výpočty a klasické molekulárně-dynamické simulace biomolekul / QM/MM výpočty a klasické molekulárně-dynamické simulace biomolekulMelcr, Josef January 2013 (has links)
Systematic calculations were performed to uncover the free energy surfaces for hydrolytic reactions of methyl-diphosphate (in vacuum and implicit solvents) and GTP in EF-Tu active site. Density functional theory and ONIOM extrapolative QM/MM scheme were adopted for the assay. In accordance with experiments, the catalytic effect of the sodium cation was mild. It changes the conformation of GTP attracting its negatively charged oxygen atoms. hydrolýze GTP. The Na+ also equilibrates the charges of all phosphate groups of the GTP mostly by transferring electrons from gamma to beta-phosphate group, which is characteristic for the intermediate states during the hydrolytic reaction.
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A Theoretical Study for the Reactivation of O<sub>2</sub> Inhibited [Fe-Fe]-hydrogenaseMotiu, Stefan January 2008 (has links)
No description available.
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Estudo teórico de interações não covalentes entre complexos trinucleares de platina (II) e DNAPaixão, Nathália Magalhães 20 February 2017 (has links)
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Previous issue date: 2017-02-20 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Câncer é um processo de crescimento e disseminação incontrolado de células e tem sido considerado como uma questão de saúde pública. Os compostos polinucleares de Platina (II) têm se mostrado muito promissores contra células cancerosas devido a interações mais rápidas e efetivas em comparação com os compostos mononucleares, como por exemplo, o complexo BBR3464. A partir disso, diversos estudos vêm sendo realizados com intuito de descrever os modos de interação de tais compostos. Este trabalho tem como objetivo fornecer um estudo teórico sistemático do complexo trinuclear de platina (II), AH78, através do uso de diferentes níveis de cálculo. Os compostos trinucleares de platina (II) estudados nesse trabalho não são capazes de formar ligações covalentes com o DNA, interagindo através da formação de grampos de fosfato, que são preferencialmente interações de hidrogênio e eletrostáticas. Dessa forma, este trabalho teve como motivação avaliar a interação dos complexos trinucleares de platina (II) não covalentes com o DNA por meio da formação de grampos de fosfato, analisadas através de modelos miméticos demonstrando presença de tais interações a partir de uma análise mais rápida e eficaz. Foram obtidas estruturas contendo uma fração de DNA que contém 6 pares de bases nitrogenadas e o complexo AH78, utilizando o método ONIOM, que comprovam a existência dos grampos de fosfato entre o complexo e o DNA. / Cancer is a process of uncontrolled growth and spread of cells and has now been considered a public health issue. Polynuclear Platinum (II) Complexes (PPCs) have shown very promising against cancer cells because of faster and more effective interactions compared to mononuclear compounds, such as the BBR3464 complex. From this, several studies have been carried out to describe the modes of interaction of such compounds. This work provides an extensive and systematic theoretical study of the platinum (II) trinuclear complex, AH78, using different base set functions for C, N and H atoms, including diffusive and polarization functions and different ECPs for platinum. The platinum (II) trinuclear compounds studied in this work are not able to form covalent bonds with DNA, interacting by the formation of phosphate bonds, which are preferably hydrogen type and electrostatic interactions. Thus, this work had the motivation to evaluate the interaction of non-covalent platinum (II) trinuclear complexes with DNA by means of the formation of phosphate clamps, analyzed using mimetic models, demonstrating that the presence of such interactions from a faster analysis is efficient. Structures containing a DNA fraction were obtained with six purine base pairs and AH78 complex using the ONIOM method, which demonstrate the existence of the phosphate clamps between the complex and the DNA.
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Calculated Vibrational Properties of Quinones in Photosynthetic Reaction CentersLamichhane, Hari Prasad, Lamichhane, Hari Prasad 14 December 2011 (has links)
This dissertation presents a detailed computational investigation into the vibrational properties of quinones involved in solar energy conversion processes in photosynthetic reaction centers. In particular, we focus on the vibrational properties of the ubiquinone molecule that occupies the QA binding site in purple bacterial photosynthetic reaction centers.
To provide a foundation upon which to base computational studies of pigments in protein binding sites density functional theory based calculations of the vibrational properties of neutral ubiquinone in the gas phase and in solvent were undertaken. From single point energy calculations it was shown that at least eight ubiquinone conformers, each with slightly different FTIR spectra, could be present in solvent at room temperature.
The calculated and experimental spectra for neutral ubiquinone in solution are very different from the spectra associated with ubiquinone in the QA binding in purple bacterial reaction centers. For this reason an ONIOM method was undertaken in which the pigment was treated using density functional theory based methods while the protein was treated using molecular mechanics. The ONIOM calculations not only modeled the experimental QA FTIR difference spectra but also resolved the long standing issue of whether a very strong hydrogen bond exists between the bound ubiquinone and the imidazole nitrogen of a histidine residue (HisM219).
To further validate the usefulness of the ONIOM approach experimental isotope edited FTIR spectra obtained using purple bacterial reaction centers with a range of chainless symmetrical quinones incorporated were modeled. Again, the agreement between the calculated and experimental spectra is outstanding.
We also modeled the vibrational properties of the ubisemiquinone anion radical both in solvent and in the QA binding site. Vibrational modes of ubisemiquinone display a greater degree of mixing of the various molecular groups of the molecule. Nonetheless the calculated FTIR spectra for ubisemiquinone in solution and in the QA site agree very well with that found experimentally. Vibrational frequencies of ubisemiquinone obtained from ONIOM calculated Raman spectra also agree very well with that found in experimental resonance Raman spectra associated with the ubisemiquinone anion radical in the QA binding site.
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Quantum Mechanical Calculation Of Nitrous Oxide Decomposition On Transition MetalsKaraoz, Muzaffer Kaan 01 November 2007 (has links) (PDF)
Nitrous oxide decomposition on Ag51, Au51, Pt22, Rh51 and Ir51 clusters representing (111) surface were studied quantum mechanically by using the method of ONIOM with high layer DFT region and low layer of molecular mechanics region utilizing universal force field (UFF). The basis set employed in the DFT calculations is the Los Alamos LANL2DZ effective core pseudo-potentials (ECP) for silver, gold, platinum, rhodium and iridium and 3-21G** for nitrogen, oxygen and hydrogen. Nitrous oxide was decomposed on the all metal surfaces investigated in this
study by leaving oxygen atom adsorbed as supported by experimental findings. Activation energies of nitrous oxide decomposition on Ag51, Au51, Pt22, Rh51 and Ir51 representing (111) surface are calculated as 14.48 kcal/mol, 15.72 kcal/mol, 7.02 kcal/mol, 3.76 kcal/mol and 5.51 kcal/mol, respectively. Based on these results, decomposition of nitrous oxide occurs on Rh more easily than other metals.
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Estudo te?rico de intermedi?rios tetra?dricos acidez / basicidade e estereosseletividade enzim?ticosSilva, S?rgio Ruschi Bergamachi 08 August 2014 (has links)
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Previous issue date: 2014-08-08 / No presente trabalho objetivou-se inicialmente, o estudo te?rico da estabilidade de
intermedi?rios tetra?dricos formados a partir de rea??es de adi??o ? carbonila utilizando
a teoria perturbativa M?ller-Plesset de segunda (MP2) e terceira ordem (MP3).
Correla??es lineares entre a diferen?a de energia eletr?nica de rea??es com ?ndices de
Wiberg e comprimentos de liga??es C-O foram obtidas, tendo sido observado que a
estabilidade dos adutos formados depende diretamente da densidade eletr?nica
envolvida entre esses ?tomos. O entendimento dos par?metros eletr?nicos dessas
estruturas possui grande import?ncia devido ao grande uso de rea??es qu?micas que em
seu curso formam este tipo intermedi?rio tetra?drico. Empregando a metodologia
ONIOM (B3LYP:AMBER), avaliou-se a estereosseletividade de uma rea??o enzim?tica
entre a enzima CAL B com um ?ster de cadeia longa. Neste estudo, foram obtidas as
energias eletr?nicas do estado inicial e do intermedi?rio da etapa lenta da rea??o da
transesterifica??o a partir das duas poss?veis faces proquirais Re e Si. O objetivo foi
estudar a enantiosseletividade da CAL B e racionaliz?-la a partir da teoria qu?ntica de
?tomos em mol?culas (QTAIM). Um estudo te?rico utilizando compostos inorg?nicos
foi realizado com o m?todo ab initio CBS-QB3 objetivando encontrar uma rela??o entre
termodin?mica e equil?brio envolvendo ?cidos e bases. Os resultados observados
mostraram uma excelente rela??o entre a varia??o da energia livre de Gibbs, ?G, de
dissocia??o de ?cidos com o ?G da rea??o de hidr?lise da base conjugada
correspondente. Observou-se, ainda, uma rela??o entre o ?G da rea??o de hidr?lise de
?cidos conjugados e seus correspondentes raios at?micos mostrando que a estabilidade
desempenha um papel importante nas rea??es de hidr?lise. A import?ncia da solvata??o
no comportamento ?cido/base quando comparado a ?Gs te?ricos e experimentais,
tamb?m foi avaliada. / The present work aimed first, the theoretical study of tetrahedral intermediate stability
formed from carbonyl addition reactions using the second (MP2) and third (MP3) order
M?ller?Plesset perturbation theory. Linear correlations between electronic energy
difference of reactions with Wiberg Indexes and C-O bond lengths were obtained, and
was observed that the stability of adducts formed depends directly of electronic density
involved between these atoms. The knowing of electronic parameters of these structures
has an important hole due to the large use on reactions that in his course forms this
tetrahedral intermediate. Employing the ONIOM (B3LYP:AMBER) methodology, was
evaluated the stereoselectivity of a enzymatic reaction between CAL B enzyme and a
long chain ester. In this study, were obtained the electronic energies of ground state and
intermediate state of transesterification rate-determing step from two possible proquirals
faces Re and Si. The objective was study the enantioselectivity of CAL B and
rationalizes it using quantum theory of atoms in molecules (QTAIM). A theoretical
study employing inorganic compounds was performed using ab initio CBS-QB3
method aiming to find a link between thermodynamic and equilibrium involving acids
and bases. The results observed showed an excellent relationship between difference in
Gibbs free energy, ?G of acid dissociation reaction and ?G of hydrolysis reaction of the
corresponding conjugate base. It was also observed, a relationship between ?G of
hydrolysis reaction of conjugate acids and their corresponding atomic radius showing
that stability plays an important role in hydrolysis reactions. The importance of
solvation in acid/base behavior when compared to theoretical and experimental ?G?s
also was evaluated.
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