Tautomerism in 11-Hydroxyaklavinone: A DFT Study

The antharquinone-based chromophore of 11-hydroxyaklavinone is present in the structure of an anticancer agent, daunomycin. On the other hand, aklavinone is the parent aglycone of certain anthracycline antibiotics that possess anti-cancer activity too. The structures of aklavinone and its 11-hydroxy derivative have many –OH groups, and two keto groups which may take place in certain tautomeric equilibria. Of these tautomeric forms, presently the one involving the anthraquinone based tautomers of 11-hydroxyaklavinone has been investigated quantum chemically in the framework of the density functional theory at the levels of RB3LYP/6-31G(d) and RB3LYP/6-31G(d,p)

Interaction of EDNA With Proton-A DFT Treatment

A composite of EDNA, with proton in vacuum have been considered within the constraints of density functional theory at the levels of B3LYP/6-31++G(d,p) (restricted and unrestricted) and ωB97X-D/6-311+G(d,p). The results of structure optimization indicated that unexpectedly hydrogen molecule production occurs by the interaction of proton and a methylenic hydrogen of EDNA resulting a carbocation formation on the explosive molecule. The remnant of the nitramine molecule is stabilized partly by the nearby nitro oxygen atoms through space. The calculated IR and UV- VIS spectra of the species were obtained and discussed

A Model Study on the Possible Effects of an External Electrical Field on Enzymes Having Dinuclear Iron Cluster [2Fe-2S]

Hydrogenases which catalyze the H2↔ 2H+ + 2e− reaction are metalloenzymes that can be divided into two classes, the NiFe and Fe enzymes, on the basis of their metal content. Iron-sulfur clusters [2Fe-2S] and [4Fe-4S] are common in ironhydrogenases. In the present model study, [2Fe-2S] cluster has been considered to visualize the effect of external electric field on various quantum chemical properties of it. In the model, all the cysteinyl residues are in the amide form. The PM3 type semiempirical calculations have been performed for the geometry optimization of the model structure in the absence and presence of the external field. Then, single point DFT calculations (B3LYP/6-31+G(d)) have been carried out. Depending on the direction of the field, the chemical reactivity of the model enzyme varies which suggests that an external electric field could, under proper conditions, improve the enzymatic hydrogen production

Electrostatic Discharge and Energetic Materials

In this short review, excerptions from the literature on electrostatic discharge  which includes  physics of electric spark, charging of organic molecules, sensitivity measurements, some theory and predictions, and electrostatic discharge   values of some group of explosives, including nitro compounds, nitramines, composites thermites, etc., have been presented

Atrans-Dinitrodiazenofuroxan Isomers-A DFT Treatise Lemi Türker

1,2,5-oxadiazole (furazanes) and their N-oxides are high-energy compounds. 4,4’-Dinitro-3,3’-diazenofuroxan is a powerful high-density high-explosives with performance comparable to that of other high-density high-explosives. Presently, isomers of trans-dinitrodiazenofuroxan are considered at the levels of B3LYP/6-31G (d, p) and B3LYP/cc-PVTZ. Various geometrical and quantum chemical characteristics obtained are discussed. For the density calculations and mono ionic forms of these isomers UB3LYP/6-31G(d,p) and  UB3LYP/6-31+G(d) type calculations have been performed, respectively. These ionic species are also found to be stable. Calculated IR, UV-VIS and 13C spectra are discussed

Contemplation on some cyclic N 8 isomers-A DFT treatment

Various cyclic N-8 isomers are considered at the levels of B3LYP/6-311 ++G(d,p) and B3LYP/cPVTZ. Some energies and molecular orbital properties are obtained. The structures are found to be stable in the singlet state but mostly unstable in the triplet. The heats of formation values calculated by means of T1 recipe reveals that they are highly endothermic. NICS(0) values have been calculated and aromaticity/antiaromaticity of the rings are discussed. Additionally, theoretical IR, UV-VIS spectra and the calculated impulse values have been obtained. (C) 2018 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license.Publisher's Versio

Interaction of TATB with Cu and Cu+1. A DFT study

Symmetric triaminotrinitrobenzene known as TATB decomposes in contact with some heavy metals, such as copper. Presently, TATB and some of its important tautomers are subjected to B3LYP/6-31G(d,p) level of treatment. Some molecular orbital energies have been obtained and compared. Then, interaction of these species with Cu and Cuþ are investigated. Although TATB has been found to be affected little by either Cu or Cuþ, undergoing only some bond length changes and/or distortions, the resonance-assisted tautomers having one to three aci groups decompose by the influence of Cu atom. In each case, only one N-OH bond rupture occursPublisher's Versio

Contemplation on the Protonation of TEX

Abstract: The possibility of acid catalyzed decomposition of TEX, a well known explosive, is considered by investigating the stability of cations formed by protonation at different sites in the molecule. For this purpose, density functional theory has been employed at the B3LYP/6-31++G(d,p) and B3LYP/6-31G(d,p) levels. Various simple cations, as well as hydrogen-bridged cations of TEX and carbocations formed from protonated TEX, are considered which may undergo further acid catalyzed cleavage routes of the molecule

Iterative estimation of total π-electron energy

In this work, the lower and upper bounds for total -electron energy (E) was studied. A method is presented, by means of which, starting with a lower bound EL and an upper bound EU for E, a sequence of auxiliary quantities E0, E1, E2, … is computed, such that E0 = EL, E0 < E1 < E2 < …, and E = EU. Therefore, an integer k exists, such that Ek E < Ek+1. If the estimates EL and EU are of the McClelland type, then k is called the McClelland number. For almost all benzenoid hydrocarbons, k = 3

McClellandov broj konjugiranih ugljikovodika

The McClelland number of a conjugated hydrocarbon is the integer k, satisfying the condition 2superscript(–(1/2))superscript(k) sqrt (2nm) ≤ E < 22superscript(–(1/2))2superscript(k+1) sqrt(2nm), where E is the HMO total Π-electron energy, n the number of carbon atoms, and m the number of carbon-carbon bonds. If k = 3, then the respective conjugated system is said to be energy-regular. If k ≤ 2 and k ≥ 4, then one speaks of energy-poor and energy-rich Π-electron systems, respectively. We found that all polycyclic Kekuléan hydrocarbons, possessing condensed rings, are energy-regular, with only three exceptions: naphthalene, phenanthrene, and triphenylene (which are energy-rich). Energy-poor Π-electron systems are some (but not all) non-Kekuléans, whereas many of the polycyclic Kekuléan hydrocarbons with non-condensed rings (polyphenyls, phenyl-substituted polyenes and similar) are energy-rich.McClellandov broj konjugiranoga ugljikovodika cijeli je broj k, koji zadovoljava uvjet 2superscript(-(1/2))superscript(k) sqrt (2nm) ≤ E < 22superscript(-(1/2))2superscript(k+1) sqrt(2nm), gdje je E ukupna HMO Π-elektronska energija, n broj ugljikovih atoma, a m broj ugljik-ugljik veza. Ako je k = 3, onda se za odgovarajući konjugirani sustav kaže da je energijski regularan. Ako je k ≤ 2 odn. k ≥ 4, onda govorimo o energijski siroma{nome odn. energijski bogatome Π-elektronskom sustavu. Našli smo da su svi policiklički Kekuléovski ugljikovodici s kondenziranim prstenima energijski regularni, uz jedina tri izuzetka: naftalen, fenantren i trifenilen (koji su energijski bogati). Energijski siromašni su neki (ali ne svi) ne-Kekuléovski Π-elektronski sustavi, dok su mnogi policiklički Kekuléovski ugljikovodici bez kondenziranih prstenova (polifenili, fenil-substituirani polieni i slični) energijski bogati