pH-dependent redox mechanism and evaluation of kinetic and thermodynamic parameters of a novel anthraquinone

Ahmad, Khurshid; Shah, Aamir Hassan; Adhikari, Bimalendu; Rana, Usman Ali; Uddin, Syed Noman; Vijayaratnam, Chandrika; Muhammad, Niaz; Shujah, Shaukat; Rauf, Abdur; Hussain, Hidayat; Badshah, Amin; Qureshi, Rumana; Kraatz, Heinz‐Bernhard; Shah, Afzal

doi:10.1039/c4ra04462b

Cited by 16 publications

(17 citation statements)

References 53 publications

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“…Moreover, direct insights into the kinetics of electrode reactions can be obtained from voltammetry. 20 The present work is expected to highlight the importance of sensitive electrochemical techniques in the establishment of such redox mechanistic pathways that could provide valuable insights about the understanding of unexplored mechanisms by which anthracenediones exert biochemical actions.…”

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confidence: 99%

pH Dependent Electrochemistry of Anthracenediones at a Glassy Carbon Electrode

Ullah

Rauf

Rana

et al. 2015

J. Electrochem. Soc.

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The voltammetric response of 1-hydroxy-2(hydroxymethyl)anthracene-9,10-dione (HAC) and 1,8-dihydroxy-4,5-dinitro anthracenedione (DHDN) was investigated at a glassy carbon electrode in acidic, neutral and basic media by cyclic, square wave and differential pulse voltammetry. The oxidation of DHDN was evidenced by the appearance of one irreversible and two reversible peaks in the square wave voltammograms. The shift of peak potentials with change in pH demonstrated proton coupled electron transfer reactions. DHDN exhibited two steps pH dependent reduction while HAC reduced in a single step involving two electrons and two protons. The square wave voltammetric response showed the quasi-reversible nature of the reduction process of HAC. However, its oxidation followed irreversible behavior. The results of sensitive voltammetric techniques helped in proposing the electrode reaction mechanism of HAC and DHDN. Moreover, physical parameters such as diffusion coefficient, pKa and electron transfer rate constant were determined from scan rate, pH and concentration effects. Aromatic compounds with reducible electrophores play significantly important role in electron transport chains and photosynthesis.1,2 The primary metabolites of such compounds have been reported to act as potent antioxidants 3,4 Some of their metabolites function in the Mitchellian redox loops of mitochondrial and chloroplast electron transport chains. Their secondary metabolites are structurally diverse compounds that play defensive roles in many organisms. Tricyclic electro-reducible compounds find extensive applications in pharmacology and industry.5 Most of the biological activities and inhibitory effects of such compounds are related to their redox behavior and hydrogen bonding characteristics.6-8 Moreover, their redox properties are greatly dependent on the nature, number and position of different substituents. The synthesis, selection and application of new bicyclic and tricyclic electroactive compounds with more selective biological activity require the understanding of factors that could tune their redox characteristics. 9 Keeping this in mind, we investigated the electrochemical fate of tricyclic compounds, 1,8-dihydroxy-4,5-dinitro anthracenedione (DHDN) and 1-hydroxy-2(hydroxymethyl)anthracene-9,10-dione (HAC) having both electron donating and withdrawing groups attached to the aromatic rings. The hydroxyl groups of DHDN are expected to result in intramolecular hydrogen bonding. The nitro and OH groups present on the basic framework of the molecule have electron withdrawing and donating mesomeric effects. The nitro groups being electron acceptor will facilitate the ionization of OH groups and thus cause to lower the pK a value of the molecule. In addition, the intramolecular hydrogen bonding of OH with keto group is expected to influence the electrochemical characteristics of the molecule. These possibilities prompted us to examine the electron transfer reactions of DHDN by electrochemical techniques.A plethora of anthracenediones have been ...

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confidence: 99%

pH Dependent Electrochemistry of Anthracenediones at a Glassy Carbon Electrode

Ullah

Rauf

Rana

et al. 2015

J. Electrochem. Soc.

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“…The CV response reveals a sharp oxidation signal, 1a, of the analyte at +0.55 V, followed by a broad peak, 2a, at +1.02 V vs Ag/AgCl. The absence of reduction peaks corresponding to 1a and 2a in the reverse scan points to the irreversible nature of these electrochemical oxidation processes [28]. In the negative potential range, the CV of HACAD shows two reduction signals labelled as 1c and 2c at potentials of -0.63 and -0.90 V, respectively.…”

Section: Cyclic Voltammetrymentioning

confidence: 99%

“…Square-wave voltammetry (SWV) has a very low detection limit due to minor contributions from the capacitive charging current [28]. Problems such as higher analyte consumption and poisoning of the electrode can be minimized by the application of SWV [39].…”

Section: Square-wave Voltammetrymentioning

confidence: 99%

“…The differential pulse voltammetric technique is associated with an enhanced sensitivity due to its ability of minimizing charging current [28]. Hence, the pHdependent redox behavior of HACAD, HAD, and of HOAD was investigated by DPV.…”

Section: Differential Pulse Voltammetrymentioning

confidence: 99%

“…S2) was inserted into equation (3) for the evaluation of DH # . The value of was obtained using equation (4) [28].…”

Section: Thermodynamic Parameters From CVmentioning

confidence: 99%

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pH- and temperature-responsive redox behavior of hydroxyanthracenediones

Ahmad

Shah

Khan

et al. 2015

Comptes Rendus. Chimie

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Biochemical Characterization, Phytotoxic Effect and Antimicrobial Activity against Some Phytopathogens of New Gemifloxacin Schiff Base Metal Complexes

Mohamed

Elshafie

Sadeek

et al. 2021

Chemistry & Biodiversity

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String of Fe(III), Cu(II), Zn(II) and Zr(IV) complexes were synthesized with tetradentateamino Schiff base ligand derived by condensation of ethylene diamine with gemifloxacin. The novel Schiff base (4E,4′E)‐4,4′‐(ethane‐1,2‐diyldiazanylylidene)bis{7‐[(4Z)‐3‐(aminomethyl)‐4‐(methoxyimino)pyrrolidin‐1‐yl]‐1‐cyclopropyl‐6‐fluoro‐1,4‐dihydro‐1,8‐naphthyridine‐3‐carboxylic acid} (GMFX‐en) and its metal complexes were identified and confirmed by elemental analyses, FT‐IR, UV/VIS, 1H‐NMR spectra, magnetic susceptibility, conductometric measurements and thermal analyses. The FT‐IR spectral data showed the chelation behavior of GMFX‐en toward the metal ions through oxygen of carboxylate group and nitrogen of azomethine group. In the light of all spectral data, these complexes presumably have octahedral geometry configurations. Thermal analysis specified that the decaying of the metal complexes exist in two or three steps with the final residue metal oxides. Antimicrobial activity of the new prepared metal complexes was screened against some common phytopathogens and their mode of action has been also discussed. The potential phytotoxic effectiveness of the new complexes was furthermore inspected on two commonly experimental plants. The complexes showed significant antimicrobial and phytotoxic effects against the majority of tested phytopathogens and the two tested plants, respectively. The potential antimicrobial activity of the complexes proved their possibility to be used successfully in agropharmacutical industry to control many serious phytopathogens. The phytotoxicity of the studied complexes also indicated their possibility as potential bio‐based herbicides alternatives to weed control in crop fields.

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pH-dependent redox mechanism and evaluation of kinetic and thermodynamic parameters of a novel anthraquinone

Abstract: The pH-dependent oxidation of a novel anthraquinone was investigated and several important kinetic and thermodynamic parameters were determined.

Cited by 16 publications

References 53 publications

pH Dependent Electrochemistry of Anthracenediones at a Glassy Carbon Electrode

pH Dependent Electrochemistry of Anthracenediones at a Glassy Carbon Electrode

pH- and temperature-responsive redox behavior of hydroxyanthracenediones

Biochemical Characterization, Phytotoxic Effect and Antimicrobial Activity against Some Phytopathogens of New Gemifloxacin Schiff Base Metal Complexes

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