Construction of core@double-shell structured energetic composites with simultaneously enhanced thermal stability and safety performance

The poor thermal stability and high sensitivity severely hinder the practical application of hexanitrohexaazaisowurtzitane(CL-20).Herein,a kind of novel core@double-shell CL-20 based energetic composites were fabricated to address the above issues.The coordination complexes which consist of natural polyphenol tannic acid(TA) and Fe~Ⅲ were chosen to construct the inner shell,while the graphene sheets were used to build the outer shell.The resulting CL-20/TA-Fe~Ⅲ/graphene composites exhibited simultaneously improved thermal stability and safety performance with only 1 wt% double-shell content,which should be ascribed to the intense physical encapsulation effect from inner shell combined with the desensitization effect of carbon nano-materials from outer shell.The phase transition(ε to γ) temperature increased from 173.70 ℃ of pure CL-20 to 191.87℃ of CL-20/TA-Fe~Ⅲ/graphene composites.Meanwhile,the characteristic drop height(H_(50)) dramatically increased from 14.7 cm of pure CL-20 to112.8 cm of CL-20/TA-Fe~Ⅲ/graphene composites,indicating much superior safety performance after the construction of the double-shell structure.In general,this work has provided an effective and versatile strategy to conquer the thermal stability and safety issues of CL-20 and contributes to the future application of high energy density energetic materials.

Hydrothermal Synthesis,Crystal Structure and Thermal Stability of a Binuclear Copper(Ⅱ) Complex with 3-(Pyridin-2-yl)-1,2,4-triazole

One novel binuclear copper（Ⅱ） complex [Cu 2 （Hpt） 2 （CO 3） 2 （H 2 O） 2 ]·H 2 O with copper carbonate and 3-（pyridin-2-yl）-1,2,4-triazole （Hpt） was hydrothermally synthesized and characterized by IR and X-ray diffraction analysis.The complex crystallizes in triclinic,space group P2 1 /n with a=0.6862（1）,b=0.7805（1）,c=1.1983（2） nm,α=72.03（2）,β=107.72（3）,γ=75.28（2）o,V=0.5884 nm 3,D c=2.105 g/cm 3,Z=1,F（000）=357,GOOF=1.041,the final R=0.01859 and wR=0.04348.The whole molecule is composed of two cooper ions,two Hpt molecules,two carbonate and three water molecules,forming a binuclear structure.The crystal structure shows that the cooper ion is coordinated with three nitrogen atoms from two Hpt molecules,two oxygen atoms from one carbonic acid and one water molecule,forming a distorted square pyramidal geometry.The TG analysis result shows that the title complex is stable under 131.0 ℃.

Synthesis,Crystal Structure and Thermal Stability of a One-dimensional Chain Cobalt Coordination Polymer [Co(4,4'-bipy)(2,4,6-TMBA)_2(CH_3CH_2OH)_2]_n

A one-dimensional chain cobalt（Ⅱ） coordination polymer with 2,4,6-trimethyl- benzoic acid, 4,4′-bipyridine and cobalt perchlorate anhydrous has been synthesized and characterized in the mixture solvent of water and alcohol. Crystal data for this complex： monoclinic, space group C2/c, a = 2.3805（8）, b = 1.1464（4）, c = 1.5807（5） nm, y = 128.435（4）°, V= 3.3791（18） nm^3, Dc = 1.246 g/cm^3, Z = 4, F（000） = 1340, final GooF = 1.009, R = 0.0504 and wR = 0.1287. Structural analysis shows that the cobalt ion is coordinated with two nitrogen atoms of one 4,4′- bipyridine molecule and four oxygen atoms from two 2,4,6-trimethylbenzoic acid molecules and two alcohol molecules, giving a distorted octahedral coordination geometry. The result of TG analysis indicates that the title complex is stable till 200 ℃.

Synthesis, Crystal Structure and Thermal Stability of a Nickel(Ⅱ) Complex with Bicycle[2.2.1]-2-hepten-5,6-dicarboxylic Acid

The nickel complex {Ni（2,2-bipy）（H2O）3[C8H11O2（COO）]}（H2O）3 with bicycle-[2.2.1]-2-hepten-5,6-dicarboxylic acid [C7H8（COOH）2] and 2,2＇-bipyridine （bipy） as ligands has been synthesized and characterized. It crystallizes in monoclinic, space group P , with a = 0.74975（3）, b = 1.20309（4）, c = 1.30593（4） nm, α = 109.861（2）, β = 98.519（2）, γ = 90.575（2）o, V = 1.09337（7） nm3, Dc = 1.552 g/cm3, Z = 2, F（000） = 524, the final GOOF = 1.064, R = 0.0397 and wR = 0.1171. The crystal structure shows that the nickel ion is coordinated with four oxygen atoms from one bicycle[2.2.1]-2-hepten-5,6-dicarboxylic acid molecule and three water molecules and two nitrogen atoms from the 2,2′-bipyridine molecule, forming a distorted octahedral coordination geometry. The result of TG analysis shows that the title complex is stable under 200.0 ℃.

Hydrothermal Synthesis, Crystal Structure,Thermal Stability and Photophysical Property of a Novel Zinc Complex with Mixed Ligands

A novel metal-organic coordination complex [Zn（CHIP）（AIC）]n （1, CHIP = 2-（4- chlorophenyl）-lH-imidazo[4,5-f][1,10]phenanthroline, A1C = 5-amino-isophthalic acid） has been synthesized by hydrothermal reactions and characterized by elemental analysis, thermogravimetric （TG） analysis, infrared spectrum （IR） and single-crystal X-ray diffraction. Complex 1 crystallizes in monoclinic, space group C2/c with a = 18.259（5）, b = 17.191（4）, c = 16.371（4） A, V= 4717（2） A3, C27H16C1NsOnZn, Mr= 575.29, Dc = 1.620 g/cm3, p（MoKa） = 1.202 mm-1, F（000） = 2335, Z = 8, the final R = 0.032 and wR = 0.074 for 4723 observed reflections （I 〉 2σ（I））. Single-crystal X-ray diffraction reveals that 1 exhibits one-dimensional （1D） double chains, which are linked by H-bond intersections into a 2D structure. TG analysis shows clear weight loss due to the decomposition of different ligands. The luminescent properties for the ligand and complex 1 were also studied.

Solvent-free Synthesis,Crystal Structure and Thermal Stability of Ionic Liquid 1-Hexadecyl-3-methylimidazolium Bromide

Ionic liquid 1-hexadecyl-3-methylimidazolium bromide [C16mim]Br was synthesized by solvent-free alkylation of N-methylimidzole with hexadecyl bromide. A large transparent single crystal of 1-hexadecyl-3-methylimidazolium bromide monohydrate （[C16mim]Br·H2O）, 4 mm in length, was firstly obtained in the water-trichloromethane-toluene growth system （Vwater＇Vtrichloromethane＇Vtoluene = 0.1：1：2）. The crystal structure was determined by single-crystal X-ray diffraction method. It crystallizes in the triclinic system, space group P1, with a = 5.4962（15）, b = 7.839（2）, c = 27.279（8） A, α = 94.375, β = 91.500, γ = 101.999°, Z = 2, V = 1145.2（5） A3, C20H41BrN2O, Mr = 405.46, Dc = 1.176 Mg/m3, μ = 1.804 mm^-1, F（000） = 436, the final R = 0.0523 and wR = 0.1345. The 3D supramolecular structure is constructed through weak interactions between imidazolium cations, Br- anions and lattice water molecules. The long alkyl chain to the imidazolium ring and lattice water molecules play an important role in the self-assembly process. Moreover, it is proposed that [C16mim]Br in water has aggregation behavior and the possible self-assembled structure is the interdigitated pattern. Finally, thermal stability of [C16mim][Br]·H2O was also studied by DSC and TGA analysis.

Synthesis,Crystal Structure and Thermal Stability Properties of a Binuclear Copper(Ⅱ) Coordination Polymer {[Cu_2(4,4'-bipy)_2(o-ABA)_4(H_2O)_2][(H_2O)_2]}_n

One-dimensional chain copper（Ⅱ） coordination polymer has been synthesized and characterized in the solvent mixture of water and alcohol with o-acetamidobenzoic acid,4,4＇-bipyridine and copper perchlorate.It is of tetragonal,space group P41212 with a=1.57756（10）,b= 1.57756（10）,c=2.1438（3）nm,V=5.3352（8） nm^3,Dc=1.524 g/cm^3,Z=4,F（000）=2536,R= 0.0479 and wR=0.0979.The crystal structure shows two coordination modes.The copper（1） is coordinated with two nitrogen atoms of one 4,4＇-bipyridine molecule and two oxygen atoms from two o-acetamidobenzoic acid molecules,forming a distorted tetrahedral coordination geometry; the copper（2） is coordinated with two nitrogen atoms of one 4,4＇-bipyridine molecule,four oxygen atoms from two o-acetamidobenzoic acid molecules and two water molecules,generating a distorted octahedral coordination geometry.The result of TG analysis shows that the title complex is stable below 180.0 ℃.

Synthesis, Crystal Structure and Thermal Stability of a New Binuclear Cu(Ⅱ) Complex with 2-Benzoylbenzoic Acid as the Ligand

A new complex Cu2（o-C6H5COC6H5COO）4（C10H8N2）2（H2O）2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows： monoclinic, space group Co, a = 14.0133（14）, b = 16.0409（16）, c = 30.372（3） A, β = 100.8950（10）°, V = 6704.1（12） A3, Dc = 1.364 g/cm3, Z = 8,μ（MoKa） = 0.704 mml, F（000） = 2840, the final R= 0.0552 and wR = 0.1431. In the crystal structure, the whole molecule consists of two copper ions, four 2-benzoylbenzoic acid molecules, two 2,2′-bipyridine molecules and two water molecules. Each central copper ion is coordinated with two nitrogen atoms from one 2,2′-bipyridine molecule and three oxygen atoms from two 2-benzoylbenzoic acids and one water molecule, respectively, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.

Hydrothermal Synthesis,Crystal Structure and Thermal Stability of a Supramolecular Lead(II) Complex with 4-Nitrobenzoic Acid and 1,10-Phenanthroline

A new complex [Pb（phen）2（4-NBA）]2·2（NO3）·H2O（phen = 1,10-phenanthroline,4-NBA = 4-nitrobenzoate） has been hydrothermally synthesized and structurally determined by single-crystal X-ray diffraction,elemental analyses and IR spectroscopy.The complex crystallizes in monoclinic,space group P21/c with a = 13.416（3）,b = 14.065（3）,c = 16.845（3）（A°） ,β = 110.55（3）o,V = 2976.5（10）（A°）^3,Z = 2,Dc = 1.796 g/cm^3,F（000） = 1564,GOOF = 0.962,the final R = 0.0686 and wR = 0.1746.The crystal structure shows that the lead ion is coordinated with two carboxylate O atoms from the 4-NBA anion,and four N atoms from two phen molecules,forming a slightly distorted pentagonalbipyramidal coordination geometry.It is further extended by various supramo-lecular interactions to form a three-dimensional supramolecular network.The TG analysis result shows that this complex begins decomposing at 30 ℃ and decompounding completely at 733 ℃.

Formation and thermal stability of connected hard skeleton structure in ATX525 cast alloys

The formation and the thermal stability of a connected hard skeleton structure(CHSS) in the matrix of Mg-5Al-2Sn-5Ca(ATX525) alloy were investigated by using X-ray diffractometer, scanning electron microscopy, differential scanning calorimeter, creep tester and isothermal treatment method. The results indicated that the CHSS composed of Mg2(Al,Ca) and Al2 Ca intermetallics was formed into a typical eutectic structure and no obvious change occurred when the samples were isothermally treated at 250 °C for 96 h and 350 °C for 72 h, respectively. It became a chained structure when isothermally treated at 450 °C for 48 h. The dissolution and reconstruction processes, however, were observed for the CHSS when the processing temperature was up to 550 °C. The creep life at the stress-temperature condition of 50MPa/200°C for the alloy treated at 450 °C for 48 h was as high as 510 h, and the strain at creep time of 100 h was as low as 0.03%, which indicated that the present alloy has not only a good thermal stability, but also a better heat resistance.

Hydrothermal Synthesis, Structure and Thermal Stability of a Copper Coordination Polymer Bridged by Pimelic Acid

A novel one-dimensional chain copper（Ⅱ） coordination polymer { [Cu（2,2′-bipy）- （HPDA）]（HPDA）（H2O）}n has been hydrothermally synthesized using pimelic acid, 2,2′-bipyridine and copper perchlorate in the mixture of water and methanol. The crystal structure was determined as a monoclinic system, space group P21/c, with a= 1.01139（14）, b = 2.6898（4）, c = 1.02105（14）, β = 109.651（2）°, V = 2.6159（6） nm^3, Dc = 1.412 g/cm^3, Z = 2, F（000） = 1164, GOOF = 1.044, R = 0.0570 and wR = 0.1448. The copper ion is coordinated with two nitrogen atoms of one 2,2′- bipyridine molecule and three oxygen atoms from two heptane diacid molecules, forming a distorted square-pyramidal geometry. The result of TG analysis shows that the title complex is stable under 200.0 ℃.

Hydrothermal Synthesis,Crystal Structure and Thermal Stability of a Novel Water Cluster [Mn(phen)_2·H_2O·Cl]·p-FBA·3H_2O

A novel water cluster [Mn（phen）2·H2O·Cl]·p-FBA·3H2O （p-FBA = p-fluorobenzoic acid and phen = 1,10-phenanthroline） was synthesized by the hydrothermal reaction of MnCl2 with p-FBA and phen at 150 ℃ and characterized by elemental analysis,IR spectra and TG. Its crystal structure was determined by X-ray single-crystal diffraction study. The crystal belongs to the triclinic system,space group P1,with a = 10.5768（1）,b = 11.5960（1）,c = 12.9916（2） ,α = 101.816（2）,β = 95.397（2）,γ = 103.052（2）o,V = 1502.8（3） 3,Z = 2,Dc = 1.463 g/cm3,R = 0.0399 and wR = 0.0997. The crystal structure shows that the manganese（Ⅱ ） ion is six-coordinated by four nitrogen atoms,one chloride ion and one oxygen atom forming a distorted octahedral coordination geometry. The structure includes three acyclically connected water molecules and one coordinated water molecule thus forming a （H2O）4 water cluster. This water pattern forms a cross-linked discrete ring. The steady （H2O）4 is further extended into a cage-like structure by the hydrogen-bonding interaction formed by dissociative aqua molecule and Cl-ligand. The dimer structure is further extended into a one-dimensional （1D） structure through C-H···O interaction. π···π Stacking interaction among adjacent phen aromatic rings further stabilizes the crystal structure.

Synthesis, Crystal Structure and Thermal Stability of a New Cadmium(II) Polymer Based on 1H-pyrazole-3-carboxylic Acid Ligand

A novel Cd（Ⅱ） coordination polymer, [CdCI（Hpc）H2O]n （1, H2pc = 1H-pyrazole-3- carboxylic acid）, was synthesized by the reaction of CdCl2·2.5H2O with H2pc, and structurally characterized by IR spectrum, UV-Vis spectrum, elemental analysis, single-crystal X-ray diffraction, as well as thermal analysis. Compound 1 crystallizes in monoclinic, P21/n space group with α = 7.0304（3）, b = 10.3047（3）, c = 10.6446（4） A, β= 107.174（4）°, F = 736.78（5） A^3, Z = 4, C4HsCdClN2O3, Mr = 276.95, Dc = 2.497 g/cm%3, F（000） = 528.0,μ= 3.281 mm^-1, R = 0.0169 and wR = 0.0387. The central metals adopt distorted octahedral geometry. Carboxyl groups of the ligand connect Cd（Ⅱ） into a one-dimensional chain, which further constructs a two-dimensional network by halogen bridging. Such two-dimensional structures are finally connected into a three-dimensional supramolecular architecture due to the hydrogen bonds and intermolecular π…π interactions. In addition, complex 1 has high thermal stability.

Crystal Structure and Thermal Stability Properties of a New 1D Chain Cu(Ⅱ)Coordination Polymer with2,3-Pyridinedicarboxylic Acid as the Ligand

A new 1D chain copper coordination polymer [CuE（H2L）2（C10HsN2）（HEO）2]n＇3n（H20） with 2,3-pyridinedi carboxylic acid （H2L） and 2,2＇-bipyridine （2,2＇-bipy） as ligands has been synthesized in the mixed ethanol and water solvents. Crystal data for this complex are as follows： monoclinic, space group P2Jc, a = 7.7713（7）, b = 27.478（3）, c = 13.2621（13）/1,, fl = 100.6940（10）, V= 2782.8（5） A3, Dc = 1.722 g/cm3, Z = 4, p = 1.61 mm-1, F（000） = 1472, the final R = 0.0363 and wR = 0.0933. In the crystal structure, the whole molecule consists of two cooper ions, two H2L, one 2,2＂-bipy molecule and six water molecules. Each central copper ion is coordinated with three oxygen atoms from two H2L and one water molecule, two nitrogen atoms from one 2,2＇-bipy molecule and two H2L, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.

Synthesis,Crystal Structure and Thermal Stability of Homopolytungstate Supporting Nickel(Ⅱ) Coordination Fragments

The orsano-inorganic hybrid compound [ Ni（phen）3] [ （H2W12O40） { Ni（phen）2H2O} { Ni（trien） } ]·2H2O was synthesized from Na2 WO4·2H2O, NiSO4·6H2O, CH3COOK, triethylenetetramine and 1,10-phenanthroline in water by the hydrothermal reaction, and characterized by IR, X-ray single crystal diffraction, and TG-DTA analysis. This compound crystallized in the monoclinic system, space group P2 （1）/n, with lattice constants： a =1.80998 （6） nm, b =2.36504（8） nm, c =2.29199（7） nm,β= 110.2220（10）°, V=9.2065（5） nm, Z=4. Final R indices R1=0.0532. ωR2=0.1295. The compound is decomposed at 593℃.

Synthesis, Crystal Structure, and Thermal Stability of a Dibutyltin Complex {[4-Et_2NC_6H_3(O)C=NC_6H_3(O)-5-NO_2](n-Bu_2Sn)}_2 and Its Interaction with DNA

The Schiff base organotin（IV） complex {[4-Et2NC6H3（O）C=NC6H3（O）-5-NO2]（n- Bu2Sn）}2 has been synthesized via the reaction between 4-（diethylamino） salicylaldehyde-2-arnino- 4-nitrophenol Schiff base （H2L） and dibutyltin oxide. Complex C1 has been characterized by IR, 1H NMR, 13C NMR spectra, and elemental analysis, and its crystal structure was determined by X-ray diffraction, It crystallizes in the monoclinic system, space group P21/n with a = 15.6559（8）, b = 9.1657（5）, c = 18.8351（10） ]A, β = 107.3440（10）°, Z = 4, V = 2579.9（2） A3, Dc = 1.442 Mg.m-3, μ（MoKa） = 1.025 mm-1, F（000） = 1152, R = 0.0250 and wR = 0.0633. The central Sn atom is coordinated in a hexadentate manner to assume a distorted octahedral configuration. Complex C1 was studied by TGA analysis in air atmosphere. The interaction between complex C1 and the herring sperm DNA was realized through the intercalation of the complex based on the studies by EB fluorescent probe.

Thermal Stability Improved by π–π Stacking Interactions: Synthesis, Crystal Structure and Thermal Decomposition of Sodium Nitroformate

An energetic salt, sodium nitroformate （NaNF）, was synthesized and characterized by elemental analysis, IR and UV spectra, and its crystal structure was first determined by single crystal X-ray diffraction. The structure exhibits two types of π-π stacking interactions between the nitroformate anions, i e, the parallel-displaced and T-shaped confgurafions. Furthermore, the thermal decomposition mechanism was investigated by DSC, TG-DTG and FTIR techniques. The kinetic parameters of the thermal decomposition were also calculated by using Kissinger＇s and Ozawa-Doyle＇s methods. The results show that NaNF has a good thermal stability, which is attributed to the π-π stacking interactions.

Hydrothermal Synthesis,Crystal Structure and Thermal Stability Properties of the Complex [Cd_2(phen)_2(C_(14)H_(11)O_3)_4(CH_3CH_2OH)]·(CH_3OH)·(H_2O)

A dinuclear cadmium complex [Cd2（phen）2（C14H11O3）4（CH3CH2OH）]·（CH3OH）·（H2O） has been synthesized with benzilic acid and 1,10-phenanthroline by hydrothermal method.The crystal structure was determined by X-ray diffraction with crystal parameters as follows：triclinic system with space group P1,a = 1.21298（10）,b = 1.32586（11）,c = 2.4815（2） nm,α = 76.2630（10）,β = 81.4500（10）,γ = 69.1700（10）o,V = 3.6143（5） nm3,Dc = 1.438 g/cm3,Z = 1,F（000） = 1600,the final GOOF = 0.937,R = 0.0521 and wR = 0.1328.In the title complex,the dinuclear structure is defined by carboxyl oxygen atoms adopting a monodentate bridged coordination mode.The coordination environment of Cd（Ⅱ） ion is CdO4N2,giving a distorted octahedral coordination geometry.TG analysis shows that the title complex is stable under 140 ℃.

Synthesis, Crystal Structure and Thermal Stability Properties of the Supramolecular Complex [Co(phen)_3][(C_6H_5)_2C(OH)COO]_2·7H_2O

One new cobalt complex [Co（phen）3][（C6Hs）2C（OH）COO]2·7H2O with benzeneacetic acid （BAA）, 1,10-phenanthroline and cobaltous perchlorate has been synthesized by means of solvent method. It crystallizes in the triclinic system, space group P^-1, with a = 1.14181（13）, b = 1.64417（18）, c = 1.65342（18） nm, α = 74.2830（10）, β= 84.4490（10）, γ = 74.9430（10）°, V = 2.8842（6） nm^3, Dc = 1.359 g/cm^3, Z = 2, F（000） = 1234, R = 0.0621 and wR = 0.1673. The crystal structure shows that the cobalt ion is coordinated with six nitrogen atoms from three 1,10-phenanthroline molecules, giving a distorted octahedral coordination geometry. There are a lot of hydrogen bonds in the complex, from which a two-dimensional network is constructed. The result of TG analysis shows that the title complex is stable below 130.0 ℃.

Synthesis, Crystal Structure, and Fluorescent and Thermal Stability Properties of Two New Cobalt(Ⅱ) Complexes with 2,2’-Bipy as Ligand

Two new cobalt（Ⅱ）complexes[Co2（2,2?-bipy）2（dpa）2（H2O）5]·4H2O（1）and Co（2,2?-bipy）3（SO4）]·7.5H2O（2）have been synthesized with diaphonic acid（H2dpa）and 2,2?-bipyridine（2,2?-bipy）as ligands.In 1,two neighboring cobalt（Ⅱ）ions are linked together by one bridging diaphonic acid group,forming an asymmetric dinuclear structure.1 crystallizes in triclinic,space group ■ with a=9.825（6）,b=13.007（8）,c=19.586（1）?,α=80.773（1）o,β=77.065（1）o,γ=85.902（1）o,Mr=431.4,V=2406.5（3）?3,Dc=1.48 g/cm3,Z=2,μ（MoKα）=0.767 mm-1,F（000）=1112,the final R=0.0379 and wR=0.0862.The central cobalt（Ⅱ）ions in 1 and 2 are coordinated with six atoms,forming distorted octahedral coordination geometry.The fluorescence and thermal stability properties of 1 and 2 are also reported.