Theoretical Design on a Series of Novel Bicyclic and Cage Nitramines as High Energy Density Compounds

We designed four bicyclic nitramines and three cage nitramines by incorporating −N­(NO₂)–CH₂–N­(NO₂)–, −N­(NO₂)–, and −O– linkages based on the HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) framework. Then, their electronic structure, heats of formation, energetic properties, strain energy, thermal stability, and impact sensitivity were systematically studied using density functional theory (DFT). Compared to the parent compound HMX, all the title compounds have much higher density, better detonation properties, and better oxygen balance. Among them, four compounds have extraordinary high detonation properties (<i>D</i> > 9.70 km/s and <i>P</i> > 44.30 GPa). Moreover, most of the title compounds exhibit better thermal stability and lower impact sensitivity than CL-20 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane) or HNHAA (hexanitro­hexaazaadamantane). Thus, all of the seven new nitramine compounds are promising candidates for high energy density compounds. In particular, five compounds exhibit a best combination of better oxygen balance, good thermal stability, excellent detonation properties superior to or comparable to CL-20 or HNHAA, and lower impact sensitivity than CL-20 or HNHAA. The results indicate that our unusual design strategy that constructing bicyclic or cage nitramines based on the HMX framework by incorporating the intramolecular linkages is very useful for developing novel energetic compounds with excellent detonation performance and low sensitivity

Preparation, characterization and compatibility studies of poly(DFAMO/AMMO)

<p>Poly(3-difluoroaminomethyl-3-methyl oxetane (DFAMO)/3-azidomethyl-3-methyl oxetane (AMMO)) (PDA) can be used as an energetic pre-polymer in the binder systems of solid propellants and polymer-bonded explosives (PBXs). The cationic solution polymerization affords PDA using butane diol (BDO) and boron trifluride etherate (TFBE) as initiator and catalyst, separately. Its molecular structure is characterized and thermal decomposition behavior is investigated by thermogravimetric analysis (TG), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). The copolymer has good thermal stability and exhibits a three-step mass-loss process with the first two steps mainly belonging to the thermal decomposition of difluoroamino and azido groups, respectively. DSC method is performed to evaluate the compatibility of PDA with some energetic components and inert materials. More than half of the selected materials are compatible with PDA, which including cyclotrimethylenetrinitramine (RDX), 2,4,6-trinitrotoluene (TNT), 1,3,5-triamino-2,4,6-trinitrobenzene (TATB), pentaerythritol tetranitrate (PETN), ammonium perchlorate (AP), ammonium nitrate (AN), potassium nitrate (KNO₃), aluminum powder (Al), aluminum oxide (Al₂O₃), 2-nitrodiphenylamine (NDPA) and 1,3-diethyl-1,3-diphenyl urea (C₁).</p

The forest plots of ln(OR) with 95%CIs for the <i>MTHFR</i> C667T in mothers for CHDs.

<p>Fixed-effects pooled OR = 1.16, 95% CI = 1.05–1.29, <i>P</i> = 0.003; <i>χ</i>² = 18.20, <i>P</i>_{heterogeneity} = 0.150.</p

Stratified analyses of the <i>MTHFR</i> C667T polymorphism in association with CHD risk under allelic model.

<p>Stratified analyses of the <i>MTHFR</i> C667T polymorphism in association with CHD risk under allelic model.</p

The forest plots of ln(OR) with 95%CIs for the <i>MTHFR</i> C667T in children for CHDs.

<p>Random-effects pooled OR = 1.30, 95% CI = 1.13–1.49, <i>P</i> = 0.000; <i>χ</i>² = 13.65, <i>P</i>_{heterogeneity} = 0.000.</p

Characteristics of the included studies.

<p>Abbreviations: CC, case-control study; TDT, transmission/disequilibrium test; CHD, congenital heart defect; PFO, patent formen ovale; ASD, atrial septal defect; PDA, patent ductus arteriosus; CoAo, coarctation of the aorta; HWE, Hardy-Weinbery equilibrium.</p

Synthesis and Characterization of Rare Earth Corrole–Phthalocyanine Heteroleptic Triple-Decker Complexes

We recently reported the first example of a europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles and have now extended the synthetic method to prepare a series of rare earth corrole–phthalocyanine heteroleptic triple-decker complexes, which are characterized by spectroscopic and electrochemical methods. The examined complexes are represented as M₂[Pc­(OC₄H₉)₈]₂[Cor­(ClPh)₃], where Pc = phthalocyanine, Cor = corrole, and M is Pr­(III), Nd­(III), Sm­(III), Eu­(III), Gd­(III), or Tb­(III). The Y­(III) derivative with OC₄H₉ Pc substituents was obtained in too low a yield to characterize, but for the purpose of comparison, Y₂[Pc­(OC₅H₁₁)₈]₂­[Cor­(ClPh)₃] was synthesized and characterized in a similar manner. The molecular structure of Eu₂[Pc­(OC₄H₉)₈]₂­[Cor­(ClPh)₃] was determined by single-crystal X-ray diffraction and showed the corrole to be the central macrocycle of the triple-decker unit with a phthalocyanine on each end. Each triple-decker complex undergoes up to eight reversible or quasireversible one-electron oxidations and reductions with <i>E</i>_1/2 values being linearly related to the ionic radius of the central ions. The energy (<i>E</i>) of the main Q-band is also linearly related to the radius of the metal. Comparisons are made between the physicochemical properties of the newly synthesized mixed corrole–phthalocyanine complexes and previously characterized double- and triple-decker derivatives with phthalocyanine and/or porphyrin macrocycles

Synthesis and Characterization of Rare Earth Corrole–Phthalocyanine Heteroleptic Triple-Decker Complexes

We recently reported the first example of a europium triple-decker tetrapyrrole with mixed corrole and phthalocyanine macrocycles and have now extended the synthetic method to prepare a series of rare earth corrole–phthalocyanine heteroleptic triple-decker complexes, which are characterized by spectroscopic and electrochemical methods. The examined complexes are represented as M₂[Pc­(OC₄H₉)₈]₂[Cor­(ClPh)₃], where Pc = phthalocyanine, Cor = corrole, and M is Pr­(III), Nd­(III), Sm­(III), Eu­(III), Gd­(III), or Tb­(III). The Y­(III) derivative with OC₄H₉ Pc substituents was obtained in too low a yield to characterize, but for the purpose of comparison, Y₂[Pc­(OC₅H₁₁)₈]₂­[Cor­(ClPh)₃] was synthesized and characterized in a similar manner. The molecular structure of Eu₂[Pc­(OC₄H₉)₈]₂­[Cor­(ClPh)₃] was determined by single-crystal X-ray diffraction and showed the corrole to be the central macrocycle of the triple-decker unit with a phthalocyanine on each end. Each triple-decker complex undergoes up to eight reversible or quasireversible one-electron oxidations and reductions with <i>E</i>_1/2 values being linearly related to the ionic radius of the central ions. The energy (<i>E</i>) of the main Q-band is also linearly related to the radius of the metal. Comparisons are made between the physicochemical properties of the newly synthesized mixed corrole–phthalocyanine complexes and previously characterized double- and triple-decker derivatives with phthalocyanine and/or porphyrin macrocycles

Synthesis and Characterization of Palladium(II) Complexes of <i>meso</i>-Substituted [14]Tribenzotriphyrin(2.1.1)

Metalation of 6,13,20,21-tetrakis-aryl-22<i>H</i>-[14]­tribenzotriphyrin­(2.1.1) (TriPs) with PdCl₂ provides Pd^II–TriP complexes in 45–56% yields. The complexes were characterized by mass spectrometry, and UV–visible absorption, magnetic circular dichroism, and ¹H NMR spectroscopy. A single crystal X-ray analysis reveals that the Pd^II–TriPs adopts a deeply saddled conformation. The palladium­(II) ion is coordinated by two pyrrole nitrogen atoms and two chloride ions to form the square-planar coordination environment. The redox properties of the Pd^II–TriPs were studied by cyclic voltammetry. Each compound undergoes one irreversible and two reversible one-electron reductions. There is a marked red-shift of the main spectral bands, relative to those of the free-base TriP ligand, due to a marked relative stabilization of the LUMO upon coordination by PdCl₂

Gold(III) Porphyrins Containing Two, Three, or Four β,β′-Fused Quinoxalines. Synthesis, Electrochemistry, and Effect of Structure and Acidity on Electroreduction Mechanism

Gold­(III) porphyrins containing two, three, or four β,β′-fused quinoxalines were synthesized and examined as to their electrochemical properties in tetrahydrofuran (THF), pyridine, CH₂Cl₂, and CH₂Cl₂ containing added acid in the form of trifluoroacetic acid (TFA). The investigated porphyrins are represented as Au­(PQ₂)­PF₆, Au­(PQ₃)­PF₆, and Au­(PQ₄)­PF₆, where P is the dianion of the 5,10,15,20-tetrakis­(3,5-di-<i>tert</i>-butylphenyl)­porphyrin and Q is a quinoxaline group fused to a β,β′-pyrrolic position of the porphyrin macrocycle. In the absence of added acid, all three gold­(III) porphyrins undergo a reversible one-electron oxidation and several reductions. The first reduction is characterized as a Au^III/Au^II process which is followed by additional porphyrin- and quinoxaline-centered redox reactions at more negative potentials. However, when 3–5 equivalents of acid are added to the CH₂Cl₂ solution, the initial Au^III/Au^II process is followed by a series of internal electron transfers and protonations, leading ultimately to triply reduced and doubly protonated Au^II(PQ₂H₂) in the case of Au^III(PQ₂)⁺, quadruply reduced and triply protonated Au^II(PQ₃H₃) in the case of Au^III(PQ₃)⁺, and Au^II(PQ₄H₄) after addition of five electrons and four protons in the case of Au^III(PQ₄)⁺. Under these solution conditions, the initial Au­(PQ₂)­PF₆ compound is shown to undergo a total of three Au^III/Au^II processes while Au­(PQ₃)­PF₆ and Au­(PQ₄)­PF₆ exhibit four and five metal-centered one-electron reductions, respectively, prior to the occurrence of additional reductions at the conjugated macrocycle and fused quinoxaline rings. Each redox reaction was monitored by cyclic voltammetry and thin-layer spectroelectrochemistry, and an overall mechanism for reduction in nonaqueous media with and without added acid is proposed. The effect of the number of Q groups on half-wave potentials for reduction and UV–visible spectra of the electroreduced species are analyzed using linear free energy relationships