Polarography of piazothiol and piazoselenol in aqueous solutions

Tsveniashvili, V. Sh.; Zhdanov, S. I.; Todres, Z. V.

doi:10.1007/bf00502668

Cited by 12 publications

(4 citation statements)

References 7 publications

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“…Turning to the LUMO energies of the acceptor fragments (Y), Figure 2 illustrates that they vary considerably with an energetic separation of some 1.6 eV between the LUMOs of the weakest acceptor, quinoxaline 85 (QX), and the strongest acceptor, benzodithiadizole 86 (B2T). The pyridine derivatives (PSe, 87 PT, 88 PX, 89 and PP 90 ) present, as expected, more stable LUMO energies (larger, i.e., more exothermic, electron affinities) than their respective benzene counterparts (BSe, 92 BT, 92 BX, 91 and QX 92 ) as a result of the inductive electronwithdrawing effect of the pyridine nitrogen. 24 Similarly, the larger inductive electron-withdrawing effect from oxygen compared to sulfur (or selenium) results in a more stable LUMO for BX and PX compared to BT and PT (or BSe and PSe).…”

Section: Resultssupporting

confidence: 74%

Donor–Acceptor Copolymers of Relevance for Organic Photovoltaics: A Theoretical Investigation of the Impact of Chemical Structure Modifications on the Electronic and Optical Properties

et al. 2012

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We systematically investigate at the density functional theory level how changes to the chemical structure of donor–acceptor copolymers used in a number of organic electronics applications influences the intrinsic geometric, electronic, and optical properties. We consider the combination of two distinct donors, where a central five-membered ring is fused on both sides by either a thiophene or a benzene ring, with 12 different acceptors linked to the donor either directly or through thienyl linkages. The interplay between the electron richness/deficiency of the subunits as well as the evolution of the frontier electronic levels of the isolated donors/acceptors plays a significant role in determining the electronic and optical properties of the copolymers.

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Section: Resultssupporting

confidence: 74%

Donor–Acceptor Copolymers of Relevance for Organic Photovoltaics: A Theoretical Investigation of the Impact of Chemical Structure Modifications on the Electronic and Optical Properties

et al. 2012

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“…Through reductive processes, nitroaromatic compounds are often converted to the corresponding amines (Heimbrook and Sartorelli 1986; Kennedy et al 1980; Knox et al 1983), whereas the reduction of benzofurazans can involve a ring-opening event (Stradyn et al 1974; Tsveniashvili et al 1966). In the case of NBF-SPh, redox-cycling may involve either of the two reductive pathways, and delineation of this mechanism would contribute to the design of future BFZs.…”

Section: Resultsmentioning

confidence: 99%

7-Nitro-4-(phenylthio)benzofurazan is a potent generator of superoxide and hydrogen peroxide

et al. 2012

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Here, we report on 7-nitro-4-(phenylthio) benzofurazan (NBF-SPh), the most potent derivative among a set of patented anticancer 7-nitrobenzofurazans (NBFs), which have been suggested to function by perturbing protein–protein interactions. We demonstrate that NBF-SPh participates in toxic redox-cycling, rapidly generating reactive oxygen species (ROS) in the presence of molecular oxygen, and this is the first report to detail ROS production for any of the anticancer NBFs. Oxygraph studies showed that NBF-SPh consumes molecular oxygen at a substantial rate, rivaling even plumbagin, menadione, and juglone. Biochemical and enzymatic assays identified superoxide and hydrogen peroxide as products of its redox-cycling activity, and the rapid rate of ROS production appears to be sufficient to account for some of the toxicity of NBF-SPh (LC50 = 12.1 µM), possibly explaining why tumor cells exhibit a sharp threshold for tolerating the compound. In cell cultures, lipid peroxidation was enhanced after treatment with NBF-SPh, as measured by 2-thiobarbituric acid-reactive substances, indicating a significant accumulation of ROS. Thioglycerol rescued cell death and increased survival by 15-fold to 20-fold, but pyruvate and uric acid were ineffective protectants. We also observed that the redox-cycling activity of NBF-SPh became exhausted after an average of approximately 19 cycles per NBF-SPh molecule. Electrochemical and computational analyses suggest that partial reduction of NBF-SPh enhances electrophilicity, which appears to encourage scavenging activity and contribute to electrophilic toxicity.

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“…Procedures for the analysis of chloropromazine sulfoxide (1048) in urine (1049), piazothiol and piazselenole (1332), and phenothiazine and derivatives (123,124) were described. Polarographic data were reported for phenothiazine derivatives (635) and for the sulfoxides and sulfones of phenothiazine, benzothiazine, and dibenzphenothiazine and their acetyl derivatives (718).…”

Section: Cl-ysi-r^n (Xx)mentioning

confidence: 99%