Heterocyclic Chemistry

KATRITZKY, A. R.

doi:10.1038/physci246032b0

Cited by 29 publications

(36 citation statements)

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“…Azoles form an important class of aromatic heterocycles [1]. Due to their biological activity, they have found use as building blocks of various drugs: anti-inflammatory (pyrazole) [2], antifungal [3] and sedative [4] (triazole) or antihypertensive [5] (tetrazole) to name only a few examples.…”

Section: Introductionmentioning

confidence: 99%

The kinetics of water-assisted tautomeric 1,2-proton transfer in azoles: a computational approach

Ozimiński

2016

Struct Chem

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A complete set of azoles undergoing 1,2-proton transfer, consisting of pyrazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole and pentazole, was computationally investigated regarding proton transfer mechanism in gas phase and water solution. Complexes of one azole molecule with 1-4 water molecules were employed to facilitate the proton transfer by lowering the activation energy, which for the isolated azole molecule is prohibitively large. The calculations were performed at the MP2/aug-cc-pVDZ and B3LYP/6-311??G(d,p) levels of theory which showed very good concordance. It follows that in the most probable transition state one azole molecule is accompanied by two water molecules. The activation barrier in water solution modelled by PCM method was lowered to 18.8 kcal/mol in the case of pyrazole and more for azoles containing more nitrogen atoms in the ring, reaching 6.8 kcal/mol in the case of pentazole. The analysis of the IRC reaction paths showed that proton transfer in the gas phase has more synchronous character and in the water solution is rather stepwise. It also follows from the analysis of bond lengths in the transition state that in the case of pyrazole the transition state is more cation-like and for other azoles, especially pentazole, is more anion-like. In the water environment, the initial step of proton transfer is moving the proton from azole to the water cluster in all cases except pyrazole, where the proton moves first from the water cluster to the azole molecule.

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Section: Introductionmentioning

confidence: 99%

The kinetics of water-assisted tautomeric 1,2-proton transfer in azoles: a computational approach

Ozimiński

2016

Struct Chem

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“…Tetrazine derivatives represent the most electron-deficient aromatic family [1][2][3] and exhibit interesting semiconducting and opto-electronic properties such as redox reversibility on reduction at low potentials [2][3][4]5 and a characteristic n → π* low energy transition, [5][6][7][8] which can be exploited in the fabrication of OLEDs, 9 OFETs, 10 and solar cells. 11,12 N-type semiconducting properties have been profusely studied either for 3,6-diphenyl-s-tetrazine (Ph 2 Tz, see Chart 1) and other diaryl-s-tetrazines (Ar 2 Tz).…”

Section: Introductionmentioning

confidence: 99%

Bis(arylene-ethynylene)-s-tetrazines: A Promising Family of n-Type Organic Semiconductors?

et al. 2015

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We theoretically describe in this work the n-type semiconducting behavior of a set of bis(arylene-ethynylene)-s-tetrazines ((ArCC) 2 Tz), by comparing their electronic properties with those of their parent diaryl-s-tetrazines (Ar 2 Tz) after the introduction of ethynylene bridges. The significantly reduced internal reorganization energy for electron transfer is ascribed to an extended delocalization of the LUMO for (ArCC) 2 Tz as opposite to that for Ar 2 Tz, which was described mostly localized on the s-tetrazine ring. The largest electronic coupling and the corresponding electron transfer rates found 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 2 for bis(phenyl-ethynylene)-s-tetrazine, as well as for some halogenated derivatives, are comparable to those reported for the best performing n-type organic semiconductors materials such as diimides and perylenes. The theoretical mobilities for the studied compounds turn out to be in the range 0.3 -1.3 cm 2 V −1 s −1 , close to values experimentally determined for common n-type organic semiconductors used in real devices. In addition, ohmic contacts can be expected when these compounds are coupled to metallic cathodes such as Na, Ca and Sm. For these reasons, the future application of semiconducting bis(phenyl-ethynylene)-s-tetrazine and its fluorinated and brominated derivatives in optoelectronic devices is envisioned.

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“…Pyrrole also reacts readily with chlorine (117). Pyridine is very aromatic with a resonance energy of 28 kcal/mole or about the same order as benzene (36 kcallmole) (118). As a result, it resists attack by electrophilic reagents, and chlorination proceeds only with difficulty.…”

Section: Ohmentioning

confidence: 99%

Environmental health sciences center task force review on halogenated organics in drinking water

Deinzer¹,

Schaumburg²,

Klein³

1978

Environ Health Perspect

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The disinfection of drinking water by chlorination has in recent years come under closer scrutiny because of the potential hazards associated with the production of stable chlorinated organic chemicals. Organic chemical contaminants are common to all water supplies and it is now well-established that chlorinated by-products are obtained under conditions of disinfection, or during tertiary treatment of sewage whose products can ultimately find their way into drinking water supplies. Naturally occurring humic substances which are invariably present in drinking waters are probably the source of chloroform and other halogenated methanes, and chloroform has shown up in every water supply investigated thus far. The Environmental Protection Agency is charged with the responsibility of assessing the public health effects resulting from the consumption of contaminated drinking water. It has specifically undertaken the task of determining whether organic contaminants or their chlorinated derivatives have a special impact, and if so, what alternatives there are to protect the consumer against bacterial and viral diseases that are transmitted through infected drinking waters. The impetus to look at these chemicals is not entirely without some prima facie evidence of potential trouble. Epidemiological studies suggested a higher incidence of cancer along the lower Mississippi River where the contamination from organic chemicals is particularly high. The conclusions from these studies have, to be sure, not gone unchallenged. The task of assessing the effects of chemicals in the drinking water is a difficult one. It includes many variables, including differences in water supplies and the temporal relationship between contamination and consumption of the finished product. It must also take into account the relative importance of the effects from these chemicals in comparison to those from occupational exposure, ingestion of contaminated foods, inhalation of polluted air, and many others. The susceptibility of different age, genetic, and ethnic groups within the population must also be carefully considered. The present review discusses: the reasons for disinfection; the general occurrence of chlorinated organics in drinking water; the chemistry in the synthesis of chlorinated organics under aqueous conditions; and alternatives to chlorine for disinfection.

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Heterocyclic Chemistry

Cited by 29 publications

References 0 publications

The kinetics of water-assisted tautomeric 1,2-proton transfer in azoles: a computational approach

The kinetics of water-assisted tautomeric 1,2-proton transfer in azoles: a computational approach

Bis(arylene-ethynylene)-s-tetrazines: A Promising Family of n-Type Organic Semiconductors?

Environmental health sciences center task force review on halogenated organics in drinking water

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