A novel zirconosilicate with the MWW topology is firstly hydrothermally synthesized in alkali media with secondary cycloamine and boric acid as a structure-directing agent (SDA) and a crystallization-supporting agent, respectively, and it is shown to be efficient for the Lewis acid-catalyzed reduction of cyclic ketone with secondary alcohol.
A newly designed polynitro cage compound with a framework of hexanitrohexaazaisowurtzitane (HNIW) was investigated by density functional theory (DFT) calculations. The molecular structure was optimized at the B3LYP/6-31G** level. IR spectrum, heat of formation (HOF), and thermodynamic properties were also predicted. The detonation velocity and pressure were evaluated by using the Kamlet–Jacobs equations, based on the theoretical density and condensed HOF. The bond dissociation energies (BDEs) and bond orders for the weakest bonds were analyzed to investigate the thermal stability of the title compound. The results show that the first step of pyrolysis is the rupture of the N8–NO2 bond. The crystal structure obtained by molecular mechanics belongs to the P21 space group, with the following lattice parameters: Z = 2, a = 11.10 Å, b = 15.15 Å, c = 10.77 Å, ρ = 1.872 g cm−3. The designed compound has high thermal stability and good detonation properties, and is a promising high-energy-density compound.
A density functional theory calculation was performed to study the molecular structures, heats of formation (HOFs), infrared spectra, detonation properties, and thermodynamic properties for five 1,2,4,5-tetrazine derivatives. Based on the full optimized molecular structures at the B3LYP/6-311++G** level, the assigned infrared spectra of the studied compounds were obtained. The isodesmic reaction method was employed to calculate the HOFs of the derivatives. The detonation velocities and pressures were also evaluated by using Kamlet−Jacobs equations with the calculated densities and condensed HOFs. The result shows that 3,6-diazido-1,2,4,5- tetrazine may be a potential candidate of high-energy density materials (HEDMs). Natural bond orbital analysis indicated that the title compounds all have higher bond dissociation energies when compared with 1,3,5,7-tetranitro-1,3,5,7-tetrazocane and 1,3,5-trinitro-1,3,5-triazinane. The results may provide basis information for the molecular design of new HEDMs.
The B3LYP/6-311G(d,p) method was used to investigate IR and Raman spectra, heat of formation, and thermodynamic properties of a newly designed polynitro cage compound 1,3,5,7,9,11-hexo(nitramine)-2,4,6,8,10,12-hexaazatetracyclo[5,5,0,0,0]dodecane. The detonation and pressure were evaluated by using the Kamlet−Jacobs equations based on the theoretical density and condensed heat of formation. The bond dissociation energies and bond orders for the weakest bonds were analyzed to investigate the thermal stability of the title compound. The results show that the N9−NO2 bond is predicted to be the trigger bond during pyrolysis. There exists an essentially linear relationship between the Wiberg bond indices of N−NO2 bonds and the charges –QNO2 on the nitro groups. The crystal structure obtained by molecular mechanics belongs to the P21 space group, with lattice parameters Z = 2, a = 10.9220 Å, b = 13.6669 Å, c = 9.4659 Å, and ρ = 2.05 g cm−3.
Quantum chemistry calculations have been performed by using the Gaussian03 program to compute the optimized geometry and harmonic vibrational frequency of 2-dicyanovinyl-5-phenylthiophene (C 14 H 8 N 2 S) in the ground state. Atomic charges at B3LYP/6-311++G(d,p) level are also calculated. Potential energy distributions (PEDs) using MOLVIB program are also used to interpret the theoretical vibrational spectra of the title compound. A detailed interpretation of the infrared spectra of the title compound is reported. The theoretical spectrograms for the IR spectra of the title compound have been constructed. The crystal structure obtained by molecular mechanics belongs to the P2 1 space group, with lattice parameters Z = 2, a = 6.6745 Å, b = 14.7672 Å, c = 11.0986 Å, = 0.921 g cm -3 . In addition, the 13 C and 1 H NMR are further investigated by the B3LYP/6-311++G(d,p) and B3LYP/6-311++G(2d,2p) methods. Résumé :On a procédé à des calculs de chimie quantique à l'aide du programme Gaussian03 pour déterminer les fréquences de vibration harmoniques pour une géométrie optimisée du 2-dicyanovinyl-5-phénylthiophène (C 14 H 8 N 2 S) à l'état fondamental. On a également calculé les charges atomiques au niveau B3LYP/6-311++G(d,p). Les distributions des énergies potentielles (PED) obtenues à l'aide du programme MOLVIB sont aussi utilisées pour interpréter les spectres vibrationnels théoriques du composé susmentionné. On présente une interprétation détaillée des spectres infrarouges de ce composé. On a construit les spectrogrammes théoriques de ces spectres infrarouges. La structure cristalline obtenue par la mécanique moléculaire appartient au groupe d'espace P2 1 ayant les paramètres de réseau Z = 2, a = 6,6745 Å, b = 14,7672 Å, c = 11,0986 Å, = 0,921 g cm -3 . En outre, on a étudié la RMN du 13 C et du 1 H par les méthodes B3LYP/6-311++G(d,p) et B3LYP/6-311++G(2d,2p). [Traduit par la Rédaction] Mots-clés : 2-dicyanovinyl-5-phénylthiophène, spectre vibrationnel, DFT, analyse RMN, charges de Mulliken.
Theoretical study of several N-nitrosodiphenylamine biological molecules has been performed using quantum computational ab initio RHF and density functional B3LYP and B3PW91 methods with 6–311G++(d,p) basis set. Geometries obtained from density functional theory (DFT) calculations were used to perform Natural bond orbital (NBO) analysis. The p characters of two nitrogen natural hybrid orbitals (NHOs) σN3−N2 increase with increasing σp values of the substituents on the benzene, which results in a lengthening of the N3–N2 bond. The p characters of oxygen NHO σO1−N2 and nitrogen NHO σO1−N2 bond orbitals decrease with increasing σp values of the substituents on the benzene, which results in a shortening of the N2=O1 bond. It is also noted that decreased occupancy of the localized σN3−N2 orbital in the idealized Lewis structure, or increased occupancy of [Formula: see text]of the non-Lewis orbital, and their subsequent impact on molecular stability and geometry (bond lengths) are also related to the resulting p character of the corresponding nitrogen NHO of σN3−N2 bond orbital.
Quantum chemical calculations of energies, geometries, and vibrational wavenumbers of 1,3-bis(4-methoxyphenyl)prop-2-en-1-one (C17H16O3) in the ground state were carried out by the using ab initio Hartree−Fock and density functional theory (DFT/B3LYP) methods with the 6-311++G** basis set. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. Theoretical vibrational spectra of the title compound were interpreted by means of potential energies distributions. The theoretical spectrograms for IR spectra of the title compound have been constructed. The analysis of natural bond orbitals shows that the intramolecular hyperconjugative interactions are formed by the orbital overlap between π*(C–C) and π(C–C) bond orbitals, which results in intramolecular charge transfer causing stabilization of the system. The predicted nonlinear optical properties of the title compound are much larger than those of urea. In addition, the analysis of frontier molecular orbitals shows that the title compound has good stability and high chemical hardness.
The performance of various density functional theories (B3LYP, B3PW91, B3P86, B1LYP, BMK, MPWB1K, PBE0, and MPWB95) was examined for calculating N–NO2 bond dissociation energies (BDEs) of 10 N-nitroacylamide compounds. The CBS-4M method was also used. By comparing the calculated results with the experimental values, it was observed that B1LYP/6–31G** and B3LYP/6–31+G** provided accurate BDEs. Especially, B3LYP/6–31+G** was recommended because of its smaller maximum absolute deviation. Further, substituent effects based on the B3LYP/6–31+G** method were analyzed. The result shows that an electron-donating group increases the BDE of the parent C6H5–CON(CH3)NO2, while an electron-withdrawing group decreases the BDE of the parent C6H5–CON(CH3)NO2. Subsequently, the BDEs of the other N-nitroacylamindes were estimated.
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