Selective electro-oxidation of d-glucose by RuCl2(azpy)2 complexes as electrochemical mediators

Bamba, Kafoumba; Léger, J.-M.; Garnier, Emmanuel; Bachmann, Christian; Servat, Karine; Kokoh, K. Boniface

doi:10.1016/j.electacta.2004.12.007

Cited by 31 publications

(24 citation statements)

References 23 publications

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“…Thus, we can admit that azopyridine ligands behave seemingly and the hindrance that they provide should have no electronic influence on the charge of Ru. However, it must certainly induce a steric effect necessary for selective reactions [6] and for the symmetry. For instance, while the three complexes δ-RuCl 2 (Azpy) 2 , δ-RuCl 2 (Dazpy) 2 and δ-RuCl 2 (Mazpy) 2 are C 2 -symmetrical with different chloride atomes, δ-RuCl 2 (Nazpy) 2 presents a C i symmetry indicating an inversion center [19].…”

Section: Nbo Analysismentioning

confidence: 99%

“…We also showed that thanks to the asymmetry of ligands, five isomers are normally obtainable. But when complex is synthesized by combining RuCl 3 ·3H 2 O with any azopyridine ligand, only both isomers cis and trans are obtained as displayed by Figure 1 [6].…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the regarding transitions are assumed to be metal to ligand charge transfer (MLCT) types. However, with γ-RuCl 2 (Nazpy) 2 , although maximum wavelength and extinction coefficient are also slightly important, HOMO is mainly made of ligand Nazpy orbital indicating that this transition is a ligand to ligand charge transfer (LLCT) type, which is not suitable for photochemical caracterisation since azopyridine ligands are reportedly insulator [6]. However, HOMO-1 is made of 63% Ru orbital and the second most important transition which wavelength is 538.2 nm with excited energy that is 2.3 ev is from H-6 to L. In consequence, we can assume that γ-RuCl 2 (Nazpy) 2 is not sufficiently active as sensitizer.…”

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confidence: 99%

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NBO Population Analysis and Electronic Calculation of Four Azopyridine Ruthenium Complexes by DFT Method

Nobel¹,

Bamba

Patrice

et al. 2017

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The molecular structure, the Natural Bond orbital (NBO) and the Time Dependent-DFT of both isomers cis or γ-Cl and trans or δ-Cl of RuCl 2 (L) 2 , where L stands respectively for 2-phenylazopyridine (Azpy), 2,4-dimethyl-6-[phenylazo]pyridine (Dazpy), 2-[(3,5-dimethylphenyl)azopyridine] (Mazpy) and 2-pyridylazonaphtol (Nazpy) were calculated with DFT method at B3LYP/LANL2DZ level. The prediction of the frontier orbitals (Highest Occupied Molecular Orbital or HOMO and Lowest Unoccupied Molecular Orbital or LUMO) shows that the most active complexes suitable for electronic reactions are admitted to be the trans isomers. Moreover, δ-RuCl 2 (Azpy) 2 is discovered to react more actively as photo-sensitizer since its energy gap is the minimum. Besides, electronic structures of all complexes through NBO calculation indicate that Ru-N bonds are made of delocalization of occupancies from lone pair orbital of N atoms to the ruthenium. Moreover, Ru was assumed to have almost the same charge regardless the structure of the azopyridine ligands in the complex indicating that the ligands provide only a steric effect that is responsible for the ruthenium's selectivity. Concerning the transition state, NBO analysis also highlights that the transition LP(Ru)π*(N 1 -N 2 ) does correspond to t 2g π*(L). This transition is assumed to correspond to Metal to Ligand Charge Transfer (MLCT) that is responsible for the photo-sensitiveness of the metallic complex. Besides, TDDFT calculation of complexes showed that δ-RuCl 2 (Nazpy) 2 displays the largest band during the absorption. For that reason, it is admitted to be the best photosensitizer due to a large system of conjugation provided by Nazpy ligand.

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Section: Nbo Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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NBO Population Analysis and Electronic Calculation of Four Azopyridine Ruthenium Complexes by DFT Method

Nobel¹,

Bamba

Patrice

et al. 2017

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“…Similar research has been undertaken before, where RuCl 2 (Azpy) 2 was the regarding complex [13]. Azpy stands for 2-phenylazopyridine.…”

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confidence: 86%

Theoretical and Electrochemical Characterization of δ-RuCl2(Nazpy)2: Application to Oxidation of D-Glucose

Ouattara¹,

Bamba²,

Ziao³

et al. 2016

AJAC

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The heterogenized δ-RuCl 2 (Nazpy) 2 deposited on carbon toray (CT) was studied for the first time as electrochemical catalyst. Before, it was characterized by visible-ultraviolet spectra and theoretically by TDDFT method at B3LYP/Lanl2DZ level. It displayed an MLCT t 2g e g → π* transition where t 2g e g due to the structure of Nazpy that considerably reduces energy between d AOs of Ru represents the HOMO of the complex and π* is identified as the LUMO. Electrochemistry study shows two redox ranges in both negative and positive sides of the potential. The positive side that corresponds to the couple Ru IV /Ru III of catalyst appears to be active for oxidation of D-glucose in carbonate buffer with a high turnover. Therefore, Keto-2-gluconic and gluconic acids were the two main products obtained with respectively 80% and 17.6% of selectivity. Moreover, a small amount of tartaric and glycol acids coming from the c-c bond cleavage due to non-protection of the anomeric carbon of D-glucose were also observed.

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“…They are produced in the same way as RuCl2 (Azpy) 2 by mixing up RuX3, 3H2O (X= Cl, Br and I) and Azpy ligand (Gowami et al 1981, Krause & Krause 1982). Although it is reported that five isomers are expected for each complex owing to the asymmetry of the Azpy ligand, only two of them are hitherto produced by the following aforementioned process (Bamba et al 2004, Velders et al 2004) as displayed in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Theoretical calculation of influence of halogen at-oms (F, Cl, Br, I) on arylazopyridine (Azpy) ruthenium complexes behaving as photo sensitizers by DFT method

Nobel

Patrice

Bamba

et al. 2018

IJAC

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Photosensivity prediction of several azopyridine ruthenium complexes by DFT and TDDFT methods was performed. g-RuX2 (Azpy) 2 and d-RuX2(Azpy)2 where X stands for F, Cl, Br and I were studied todetermine their activities when halide atoms shift. So, frontier orbital, NBO, NLMO and MLCT transitions as well as an excited lifetime of those complexes was determined. The main difference between them stems from both the electronegativity of the halide atoms and the structure of each complex. Hence, the rank of halide's electronegativity that is as followscp(F)>cp (Cl)>cp (Br)>cp (I) has been discovered to influence all the reactivity of the complexes regardless their structure. Herein, the comparison with the gap energy shows that the most reactive complexes are those with fluorine atom. Especially, d-RuF2(Azpy)2 was admitted to be the most active isomer. Moreover, NBO calculation discloses that the complex becomes less ionic when the electronegativity decreases from F to I atoms. Furthermore, the calculation of NLMO orbitals shows that the bonding Ru-X are very strong. However, this strength decreases also from F to I and the nature of the bonding move from ionic to metallic. Moreover, the bonding from Npy and N2 with Ru are known to be the same confirming the bidentate state of Azpy ligand. Regarding the electronic prediction, the eight complexes are surely assumed to display MLCT transitions that originate the photosensitivity. However, the complex that requires the least energy remains d-RuF2(Azpy)2. This result was also determined by analyzing the excited lifetime that is the ability for a complex to longer linger in the cationic state. At last, we found out that with iodine atoms, the azopyridine ruthenium complex cannot behave as photosensitize dye insofar as I atom hides the main orbitals from Ru regardless the symmetry.

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Selective electro-oxidation of d-glucose by RuCl2(azpy)2 complexes as electrochemical mediators

Cited by 31 publications

References 23 publications

NBO Population Analysis and Electronic Calculation of Four Azopyridine Ruthenium Complexes by DFT Method

NBO Population Analysis and Electronic Calculation of Four Azopyridine Ruthenium Complexes by DFT Method

Theoretical and Electrochemical Characterization of <i>δ</i>-RuCl<sub>2</sub>(Nazpy)<sub>2</sub>: Application to Oxidation of D-Glucose

Theoretical calculation of influence of halogen at-oms (F, Cl, Br, I) on arylazopyridine (Azpy) ruthenium complexes behaving as photo sensitizers by DFT method

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Selective electro-oxidation of d-glucose by RuCl2(azpy)2 complexes as electrochemical mediators

Cited by 31 publications

References 23 publications

NBO Population Analysis and Electronic Calculation of Four Azopyridine Ruthenium Complexes by DFT Method

NBO Population Analysis and Electronic Calculation of Four Azopyridine Ruthenium Complexes by DFT Method

Theoretical and Electrochemical Characterization of &lt;i&gt;δ&lt;/i&gt;-RuCl&lt;sub&gt;2&lt;/sub&gt;(Nazpy)&lt;sub&gt;2&lt;/sub&gt;: Application to Oxidation of D-Glucose

Theoretical calculation of influence of halogen at-oms (F, Cl, Br, I) on arylazopyridine (Azpy) ruthenium complexes behaving as photo sensitizers by DFT method

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Theoretical and Electrochemical Characterization of <i>δ</i>-RuCl<sub>2</sub>(Nazpy)<sub>2</sub>: Application to Oxidation of D-Glucose