Browsing by Author "Nome, Faruk"

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    Dephosphorylation Reactions of Mono-, Di-, and Triesters of 2,4-Dinitrophenyl Phosphate with Deferoxamine and Benzohydroxamic Acid
    (2012) Medeiros, Michelle; Orth, Elisa S.; Manfredi, Alex M.; Pavez Guerrero, Paulina Isabel; Micke, Gustavo A.; Kirby, Anthony J.; Nome, Faruk
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    Investigation about the complexation of trimethylammonium-derived pillar[5]arene with indole and azaindole derivatives
    (2019) Montecinos Escobar, Rodrigo Andrés; Diaz-Wilson, Fernanda; Bravo-Sepulveda, Alexis; Salas,Cristian O.; Recabarren Gajardo, Gonzalo; Nome, Faruk
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    Ionic liquids: anion effect on the reaction of O,O-diethyl O-(2,4-dinitrophenyl) phosphate triester with piperidine
    (2015) Pavez, Paulina; Millan, Daniela; Cocq, Cristian; Santos, Jose G.; Nome, Faruk
    The reactions of O,O-diethyl 2,4-dinitrophenylphosphate triester (1) with piperidine in ionic liquids and four conventional organic solvents (COS) were subjected to kinetic and product studies. Analytical techniques (UV-vis and NMR) identified two pathways: nucleophilic attack at the phosphoryl center and at the C-1 aromatic carbon. The nucleophilic rate constants (k(N)(T)) for these parallel reactions were separated into two terms: k(N)(P) and k(N)(Ar) for the corresponding electrophilic centers. Both the rate and the selectivities of the reactions are strongly dependent on the nature of the ionic liquid used, and a good correlation with the solvent acceptor capacity to form hydrogen bonds (beta) was observed. Remarkably, an exclusive attack at the phosphoryl center was found using [Bmim] DCA, [Bmpyrr] DCA and [Bmpy] DCA as the reaction solvents. In contrast, with [Bmim]PF6 as the reaction solvent, attack at the C-1 aromatic was the main path (94%). These results suggest that ionic liquids can be considered to be designer solvents because by an appropriate choice of the anion it is possible to steer the selectivity of this reaction.
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    Supramolecular kinetic effects by pillararenes: the synergism between spatiotemporal and preorganization concepts in decarboxylation reactions†
    (2021) Vieira Silveira, Eduardo; Montecinos, Rodrigo; Scorsin, Leandro; Garcia-Rio, Luis; Medeiros, Michelle; Nascimento, Vanessa; Nome, Faruk; Affeldt, Ricardo F.; Micke, Gustavo A.
    A study about spontaneous decarboxylation reactions of 3-carboxy-1,2-benzisoxazole (CBI) nitrated derivatives (6-NitroCBI and 5,6-DinitroCBI) compared with supramolecular kinetic effects promoted by two cationic pillararenes (P5A and P6A) has been carried out and brings contributions to advance current theories related to supramolecular and enzymatic catalysis/inhibition. A higher energy barrier to spontaneous hydrolysis of 6-NitroCBI relative to that of 5,6-DinitroCBI (Delta Delta G(double dagger) = 2.98 kcal mol(-1)) was determined experimentally, however similar transitions states were observed for both substrates. The host-guest complexes generated catalytic effects up to 7.1-fold on k(obs), except for 6-NitroCBI subset of P5A which is the only system that presented unprecedent inhibitory kinetic effects. The data (kinetics, H-1 NMR titration and molecular dynamic simulations) elucidated the kinetic effects of the four complexes as a result of their geometries, more specifically, by modifying 3 main factors: (1) number of hydrogen bonds between solvent and carboxyl groups of the CBIs, (2) polarization of the O-N bond of the isoxazole ring and (3) reduction of the inductive effect of NO2 groups by field effects. The data from the present study encourage the use of both spatiotemporal and preorganization theories during interpretations related to supramolecular and enzymatic catalysis.
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    Supramolecular phosphate transfer catalysis by pillar[5]arene
    (2016) Liz, Daiane G.; Manfredi, Alex M.; Medeiros, Michelle; Montecinos Escobar, Rodrigo Andrés; Gómez-González, Borja; García Río, Luis; Nome, Faruk