Comportamiento electroquímico de nitrocompuestos : síntesis y reducción electroquímica de 4-nitroimidazoles sustituidos y su comparación con 2- y 5-nitroimidazoles

Nitroimidazoles han sido fuente de muchas investigaciones en razón de sus propiedades como antibióticos, radiosensibilizadores y antiprotozoarios. El mecanismo de acción farmacológica de estos compuestos es fuertemente relacionada con la reducción de ellos, principalmente la reducción monoelectrónica para formar el anión radical nitro. En consecuencia, la electroquímica de estos compuestos desempeña un papel importante en su mecanismo de acción. En la presente tesis se ha llevado a cabo un amplio estudio en una serie de derivados nitroimidazólicos con el objetivo de caracterizar su comportamiento electroquímico en diferentes medios. Para este propósito se ha estudiado el comportamiento electroquímico de algunos derivados 4-nitroimizadólicos de síntesis como: 1-metil-2-hidroximetil-4-nitroimizadol; 1-metil-4-nitroimizadol-2-carboxialdehido; ácido 1-metil-4-nitroimizadol-2-carboxilico; 2-hidroximetil-4-nitroimizadol; 4-nitroimizadol-2-carboxialdehido y se comparó con otros derivados 2- y 5-nitroimizadólicos. El estudio electroquímico se realizó usando fundamentalmente Voltamperometría cíclica pero también se usó otras técnicas como Polarografía Tast y de Pulso Diferencial, Voltamperometría de Barrido Lineal, Electrolisis a Potencial Controlado y Culombiometría.--------------------------------------------------------Nitroimizadoles have been the source of many investigations because of their properties as antibiotics, radiosensitizers and antiprotozoans. The pharmacological mechanism of action of these compounds is strongly connected with the reduction of them, mainly the one-electron reduction to form the nitro radical anion. Consequently the electrochemistry of these compounds plays an important role in its mechanism of action. In the present theses we have carried out comprehensive studies about a series of nitroimizadole derivatives in order to characterize its electrochemical behaviour in different media. For this purpose we have studied the electrochemical behaviour of some synthesized 4-nitroimizadole derivatives such as: 1-methyl-2-hydroxymethyl-4-nitroimizadol; 1-methyl-4-nitroimizadol-2-carboxyaldehyde; 1-methyl-4-nitroimizadol-2-carboxylic acid; 2-hidroximetil-4-nitroimizadol; 4-nitroimizadol-2-carboxyaldehyde and compared with other 2-and 5-nitroimizadol derivatives. The electrochemical study was carried out using mainly Cyclic Voltammetry but also other electrochemical techniques such as Tast and Diferential Pulse Polarography, Linear Sweep Voltammetry, controlled potential electrolysis and coulommetry were used

Nitrofluorene derivatives trapped within MWCNTs for electrocatalysis of NADH: Substituent effects on π-π stacking interaction strength

We describe nanostructured electrode platforms composed of multiwalled carbon nanotube/glassy carbon electrodes (MWCNT/GCEs) with entrapped nitroaromatic compounds such as 2-nitrofluorene (2-NF), 2-nitro-9- fluorenone (2-NFN), 2,7-dinitrofluorene (2,7-NF) and 2,7-dinitro-9-fluorenone (2,7-NFN). All of the above ni- troaromatic compounds were tested as precursors for the production of redox mediator couples useful for NADH electrocatalysis. In this communication, we reveal the effect of the substituents on both the π-π stacking interaction strength and the electrocatalysis of NADH. The results show that the nitro group plays a triple role: it acts as a precursor of the mediator redox couple for NADH electrocatalysis; it increases the π-π stacking interaction with the electrode; and it acts as an electron acceptor substituent that promotes the electrocatalysis of NADHWe thank FONDECYT Grant 1170054 and 1210899 for financial supportDepartamento de Ingeniería Química, Química Física y Ciencias de los Materiale

Voltammetric behavior of 3,5-dinitrobenzoic acid in solution on GCE and encapsulated on multiwalled carbon nanotube modified electrode

The cyclic voltammetric behavior of 3,5-dinitrobenzoic acid (3,5-DNB) in 0.1 M PBS of pH 7 was examined at a glassy carbon electrode (GCE). 3,5-DNB was found to produce two irreversible reduction peaks corresponds to the reduction of each nitro group in the 3,5-DNB molecule. Our results contradict previous studies (P.Gopal et al. Journal of Molecular Liquids 178 (2013) 168-174) wherein the same peaks are assigned as, the first, to the reduction of the nitro group to hydroxylamine and the second, to the subsequent reduction to amine derivative. Also we report that GCE modified with multiwalled carbon nanotubes (MWCNTs) can be derivatized with 3,5-DNB. The derivatization procedure involves simple immersion of the MWCNT-modified electrode in a solution containing 3,5-DNB. SEM images reveals that the network of nanotubes form a homogeneous, twisted, densely packed, three-dimensional array that remains attached to the GCE surface. Both electrochemical and SEM measurements indicate that 3,5-DNB is encapsulated on the electrode, most probably by being trapped within the pockets of the mentioned three-dimensional array, without formation of covalent bonding

The crystal structure of 4-(pyren-1-yl)butyl-4-nitrobenzoate, C27H21NO4

C27H21NO4, triclinic, P1‾ $P\overline{1}$ (no. 2), a = 7.3476(2) Å, b = 7.4894(2) Å, c = 20.5137(5) Å, α = 89.33000(10)°, β = 79.7070(10)°, γ = 67.5220(10)°, V = 1024.31(5) Å3, Z = 2, R gt(F) = 0.0536, wR ref(F 2) = 0.1792, T = 296.15 K

Polarographic and microcalorimetric study of the interaction between glutathione and amoxycillin

The enthalpies of the reaction between glutathione and amoxycillin have been measured directly using a flow microcalorimeter. Comparative results are obtained by using an ac polarographic method previously developed in our laboratories. The results obtained imply that glutathione reacts with amoxycillin spontaneously and that this process is exothermic at physiological pH and temperature. Evidence of this interaction is very important in order to permit the postulation of a new biotransformation route for amoxycillin. Furthermore, the comparable results of two very different methods strongly support our previous statement that polarography is a very important tool for the study of interactions of biological significance. © 1988.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Polarogaphic and microcalorimetric study of the interaction between glutathione and amoxycillin

The enthalpies of the reaction between glutathione and amoxycillin have been measured directly using a flow microcalorimeter. Comparative results are obtained by using an ac polarographic method previously developed in our laboratories. The results obtained imply that glutathione reacts with amoxycillin spontaneously and that this process is exothermic at physiological pH and temperature. Evidence of this interaction is very important in order to permit the postulation of a new biotransformation route for amoxycillin. Furthermore, the comparable results of two very different methods strongly support our previous statement that polarography is a very important tool for the study of interactions of biological significance. © 1988.SCOPUS: ar.jinfo:eu-repo/semantics/publishe