Abstract:Density functional theory calculations were performed on crystalline 2,6-diamino-3,5-dinitropyridine-1-oxide (ANPyO). The conduct bands are generally quite flat, while the valence bands are uneven. The carbon, oxygen and amino nitrogen atoms make up the narrow lower energy levels. While the carbon, amino nitrogen and atoms in nitro group make up the higher energy levels. Change of electronic charges for the decrease of the cell edge a and c are almost the same, but different from the decrease of the cell edge … Show more
“…In the theoretical study by He et al [173], periodic DFT calculation was used to investigate crystalline 2,6-diamino-3,5-dinitropyridine-1-oxide, an important explosive and raw materials for preparing high energetic explosive. The insight into chemical molecular properties was obtained by analyzing band structures, densities of states and charge distributions.…”
In the current review the content of the journal Structural Chemistry for the calendar year 2010 is related to thermochemistry. To a short summary of each article in this volume of the journal a thermochemical comment is added.
“…In the theoretical study by He et al [173], periodic DFT calculation was used to investigate crystalline 2,6-diamino-3,5-dinitropyridine-1-oxide, an important explosive and raw materials for preparing high energetic explosive. The insight into chemical molecular properties was obtained by analyzing band structures, densities of states and charge distributions.…”
In the current review the content of the journal Structural Chemistry for the calendar year 2010 is related to thermochemistry. To a short summary of each article in this volume of the journal a thermochemical comment is added.
“…Note that in reference [1], 3,5-diamino-2,6-dinitropyridine-N-oxide also was named as DADNPO. The constitutional isomer of it, namely 2,6-diamino-3,5-dinitropyridine-N-oxide (DADNPO) (II) has ample number of references in the literature [2][3][4][5][6][7], contrary to the presently considered 3,5-diamino isomer (I). Chavez mentioned 3,5-diamino-2,6-dinitropyridine-N-oxide in his book chapter that he and his coworkers attempted to prepare the 2,6dinitro-3,5-diaminopyridine 1-oxide but they were unsuccessful [8].…”
The titled structure possesses many electron donating and attracting groups and should have push-pull type character. Its constitutional isomer, 2,6-diamino-3,5-dinitropyridine-N-oxide is a heat-resistant explosive material. In the present article, the charged forms of the titled structure have been investigated within the constraints of density functional theory at the level of UB3LYP/6-31++G(d,p). The calculations have revealed that it is electronically less stable than its isomer, 2,6-diamino-2,5-dinitropyridine-N-oxide. Some structural, electronic, quantum chemical and spectral behavior of ±1, ±2 type ions of it are considered presently.
In this work, the experimental synthesized bipyridines 3,3'-Dinitro-2,2'-bipyridine (DNBPy), 3,3'-Dinitro-2,2'-bipyridine-1,1'-dioxide (DNBPyO), and (3-Nitro-2-pyridyl)(5-nitro-2-pyridyl) amine (NPyA), and a set of designed dipyridines that have similar frameworks but different linkages and substituents with NPyA were studied theoretically at the B3LYP/6-31G* level of density functional theory. The gas-phase heats of formation were predicted based on the isodesmic reactions and the condensed-phase heats of formation and heats of sublimation were estimated in the framework of the Politzer approach. The crystal densities have been computed from molecular packing. Results show that this method gives a good estimation of density in comparison with the available experimental data for DNBPy, DNBPyO, and NPyA. The predicted detonation velocities and pressures indicate that the performance of dipyridines linked with -O-, -NH-, or -CH₂- bridges have not been improved compared with that of the directly linked dipyridines, but all derivatives have better detonation properties than DNBPy, DNBPyO, and NPyA because of the presence of more nitro groups. An analysis of the bond dissociation energies (BDEs) or the impact sensitivity (h₅₀) suggests that introduction of different bridges but not substituents has little influence on thermal stability. The calculated h₅₀ may be more reliable than BDE for predicting stability. Four bridged bipyridines have quite good detonation performance and low sensitivity.
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