Electrochemical Studies on Some Pyrazole, Oxadiazole, and Thiadiazole Derivatives

Abou‐Elenien, G. M.; Ismail, Nagwa Abdallah; El‐Maghraby, A. A.; Al-abdallah, G. M.

doi:10.1002/1521-4109(200108)13:12<1022::aid-elan1022>3.0.co;2-x

Cited by 15 publications

(6 citation statements)

References 31 publications

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“…From the model proposed in Scheme 1, it can be concluded that above pH 4.0, the negative charge density on the Hpyt end group hardly affects or even inhibits the h ET reaction of the probe, as can be seen from the voltammograms presented in Figure 5. Therefore, the voltammetric profiles presented in Figure 4 (pH = 6.0) can be explained by considering that longer immersion times decrease the density of pinholes increasing the negative 6 ] 3+ probe molecule, the opposite charges seems to favor or, at least, not affect the heterogeneous molecular recognition process. Also, for this compound, the electrostatic interaction may be inducing a closer approach to the electrode surface.…”

Section: Inorganic Complexes As Probe Moleculesmentioning

confidence: 96%

“…5,6 Despite these aspects, there are no data in the literature concerning the use of this type of compound as electrochemical biological sensor. Within this compound class, 5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) species is particularly interesting because of the possibility to study the effect of SAM protonation equilibrium, which is one of the processes that influence h ET .…”

Section: Introductionmentioning

confidence: 99%

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5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

Paulo

Silva

Pinheiro

et al. 2008

J. Braz. Chem. Soc.

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O composto 5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) adsorve espontaneamente sobre ouro formando SAMs ("Self-Assembled Monolayers") que, de acordo com os resultados eletroquímicos e de STM ("Scanning Tunneling Microscopy"), contêm poros através dos quais as moléculas dos complexos [Fe(CN) 6 ] 4-, a dependência da corrente faradáica com o pH da solução eletrolítica permitiu o cálculo do pKa da molécula de Hpyt adsorvida sobre ouro (4,2). Os parâmetros termodinâmicos, H ads and G ads , para o processo de adsorção desta molécula foram estimados em -20,01 e -39,39 kJ mol -1 , respectivamente, utilizando-se o modelo de Langmuir. O processo redox da metaloproteína citocromo c foi estudado utilizando-se a SAM de Hpyt. A constante de velocidade heterogênea de transferência de elétrons foi calculada em 2,29 10 -3 cm s -1 .5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol (Hpyt) spontaneously adsorbs on gold forming SAMs (self-assembled monolayers) that, based on STM (Scanning Tunneling Microscopy) and electrochemical data, contain pinholes through which [Fe(CN) 6 ] 4-and [Ru(NH 3 ) 6 ] 3+ probe molecules access the underlying gold electrode. For the former molecule, the dependence of the faradaic current on the electrolyte solution pH value allowed the evaluation of the surface pKa as 4.2. The thermodynamic parameters H ads and G ads for the Hpyt adsorption process could be described by the Langmuir model and were calculated as -20.01 and -39.39 kJ mol -1 , respectively. Electrodic redox reaction of cytochrome c metalloprotein was accessed by using the Hpyt SAM with a heterogeneous electron transfer rate constant of 2.29 10 -3 cm s -1 .

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Section: Inorganic Complexes As Probe Moleculesmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

Paulo

Silva

Pinheiro

et al. 2008

J. Braz. Chem. Soc.

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“…The electrochemistry of heterocyclic compounds with nitrogen heteroatom has been extensively studied [1][2][3][4][5][6][7][8][9]. In spite of great importance and wide uses of the heterocyclic aromatic compounds with oxygen or sulphur atoms, it is rare to find an attempt to study their electrochemical redox characteristics.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical Study of Some Substituted Chromene Derivatives in Nonaqueous Media at Pt, Au and Glassy Carbon Electrodes

El‐Maghraby¹

2009

TOELECJ

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Abstract:The redox characteristics of some substituted chromene derivatives has been investigated in different nonaqueous solvents such as, 1,2-dichloroethane (DCE), dichloromethane (DCM) and acetonitrile (AN) using 0.1mol dm -3 tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte at platinum, gold and glassy carbon electrodes, using cyclic voltammetry. Through controlled potential electrolysis (CPE), the product of oxidation and reduction can be separated and identified. The product of oxidation was found to be the corresponding bis-compound. On the other hand, the reduction occurs in a single two electron process to give the dianion, which abstracts protons to saturate the (-C=O) bond. The effect of substituents on the redox mode of an electroactive site has also been studied.

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“…[24][25][26][27] However, the cyclic voltammograms (CV) of pyrazoles show a high oxidation potential and lack of reduction potential. 28 This means that the oxidized forms of pyrazoles do not have enough stability on the electrolysis timescale when Ip C /Ip A approaches zero, and there would be rapid solvolysis or polymerization. Thus, in electro-organic synthesis, pyrazole derivatives are not usually used as appropriate electrophiles under mild reaction conditions.…”

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confidence: 99%

Electrochemically Catalyzed N–N Coupling and Ring Cleavage Reaction of 1H-Pyrazoles

Zandi¹,

Sharafi‐Kolkeshvandi²,

Nikpour³

2021

Synthesis

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The electrocatalyzed N–N coupling and ring cleavage reaction of 3-methyl-, 3,5-dimethyl-, 3-methyl-5-phenyl- and 3,5-diphenyl-1H-pyrazole was investigated and led to the electro-organic synthesis of new heterocyclic compounds. The results revealed that electrochemically produced 1H-pyrazoleox plays the role of acceptor in a reaction with the starting molecule via a N–N coupling and ring cleavage reaction of pyrazoles. The proposed reaction sequence consists of anodic oxidation, dimerization, rearrangement and reduction. The electrochemically catalyzed reactions were accomplished under constant-current and constant-potential conditions using an undivided electrochemical cell with the advantages of mild reaction conditions, remarkable yields and environmental compatibility.

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Electrochemical Studies on Some Pyrazole, Oxadiazole, and Thiadiazole Derivatives

Cited by 15 publications

References 31 publications

5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

5-(4-pyridinyl)-1,3,4-oxadiazole-2-thiol on gold: SAM Formation and electroactivity

Electrochemical Study of Some Substituted Chromene Derivatives in Nonaqueous Media at Pt, Au and Glassy Carbon Electrodes

Electrochemically Catalyzed N–N Coupling and Ring Cleavage Reaction of 1H-Pyrazoles

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