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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Probing the geometry reorganization from solution to gas-phase in putrescine derivatives by IRMPD, H-1-NMR and theoretical calculations

Texto completo
Autor(es):
Correra, Thiago Carita ; Fernandes, Andre Santos ; Reginato, Marcelo Mota ; Ducati, Lucas Colucci ; Berden, Giel ; Oomens, Jos
Número total de Autores: 6
Tipo de documento: Artigo Científico
Fonte: Physical Chemistry Chemical Physics; v. 19, n. 35, p. 24330-24340, SEP 21 2017.
Citações Web of Science: 4
Resumo

Single and double protonated (E)-1,4-diamine-2-butenes were evaluated as a model system to probe isomerization during the ESI processes employing infrared multiple-photon dissociation (IRMPD) spectroscopy and density function theory (DFT) calculations, including implicit and explicit solvation models. Our results show that the preferential protonation takes place at the amines for singly protonated species and that the double bond is not protonated even under double protonation, as expected from known pK(a) values. This behavior was shown to reflect the (E)-(Z) interconversion rate, as no interconversion was observed nor predicted by implicit solvation model based on density (SMD) calculations even by the olefin protonation pathway. Explicit solvent calculations show that the singly protonated (E) configuration observed in the gas phase is also the most stable configuration in solution due to molecular interactions with the solvent that are absent for the (Z) configuration. The explicit solvation calculation reverts the supposed gas-phase stability of the (Z) configuration in comparison to (E) from -9 kcal mol (-1) (in relative Gibbs free energy) in the gas phase to +89 kcal mol(-1) (in total potential energy) as depicted by explicit Monte Carlo (MC) simulations. Together with previous results for the saturated 1,4-diamines from Morton and coworkers that show the (Z) configuration related conformation to be the most stable geometry in the gas-phase due to intermolecular hydrogen bonding, our experiments clearly show that conformational reorganizations can take place during the ESI process. These results suggest that gas-phase experiments and vacuum calculations may not be valid as evidence for conformations in solution without prior testing to check for isomerization during the ESI process. (AU)

Processo FAPESP: 14/15962-5 - Mecanismos de reação de sistemas catalíticos assimétricos por espectrometria de massas e espectroscopia vibracional de íons na fase gasosa
Beneficiário:Thiago Carita Correra
Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores
Processo FAPESP: 15/08541-6 - Ressonância magnética nuclear: além da determinação estrutural
Beneficiário:Claudio Francisco Tormena
Linha de fomento: Auxílio à Pesquisa - Temático
Processo FAPESP: 15/11769-9 - Isolamento de intermediários reativos da epoxidação de Sharpless e caracterização dessas espécies por cálculos teóricos
Beneficiário:André Santos Fernandes
Linha de fomento: Bolsas no Brasil - Iniciação Científica
Processo FAPESP: 15/08539-1 - EMU concedido no processo 2014/15962-5: espectrômetro de massas tipo íon TRAP modificado para realização de espectroscopia vibracional no infravermelho (IRMPD)
Beneficiário:Thiago Carita Correra
Linha de fomento: Auxílio à Pesquisa - Programa Equipamentos Multiusuários
Processo FAPESP: 14/21930-9 - Estudo do efeito do solvente na constante de acoplamento 1JPt-Tl em complexos de metais pesados por dinâmica molecular ab initio
Beneficiário:Lucas Colucci Ducati
Linha de fomento: Bolsas no Exterior - Pesquisa