Molecular Dynamics Simulation of Shock Response of CL-20 Co-crystals Containing Void Defects

To investigate the effect of void defects on the shock response of hexanitrohexaazaisowurtzitane(CL-20)co-crystals,shock responses of CL-20 co-crystals with energetic materials ligands trinitrotoluene(TNT),1,3-dinitrobenzene(DNB),solvents ligands dimethyl carbonate(DMC) and gamma-butyrolactone(GBL)with void were simulated,using molecular dynamics method and reactive force field.It is found that the CL-20 co-crystals with void defects will form hot spots when impacted,significantly affecting the decomposition of molecules around the void.The degree of molecular fragmentation is relatively low under the reflection velocity of 2 km/s,and the main reactions are the formation of dimer and the shedding of nitro groups.The existence of voids reduces the safety of CL-20 co-crystals,which induced the sensitivity of energetic co-crystals CL-20/TNT and CL-20/DNB to increase more significantly.Detonation has occurred under the reflection velocity of 4 km/s,energetic co-crystals are easier to polymerize than solvent co-crystals,and are not obviously affected by voids.The results show that the energy of the wave decreases after sweeping over the void,which reduces the chemical reaction frequency downstream of the void and affects the detonation performance,especially the solvent co-crystals.

One-step rapid preparation of CL-20/TNT co-crystal assembly and spheroidized coating based on droplet microfluidic technology

Energetic materials pose challenges in preparation and handling due to their contradictory properties of high-energy and low-sensitivity.The emergence of co-crystal explosives is a new opportunity to change this situation.If the co-crystal explosive is coated into spherical particles with uniform particle size distribution,this contradiction can be further reduced.Therefore,binder-coated hexanitrohexaazaisowurtzitane/2,4,6-trinitrotoluene(CL-20/TNT)co-crystal microspheres were prepared by droplet microfluidic technology in this work.The coating effects of different binder formulations of nitrocellulose(NC)and NC/fluorine rubber(F2604)on the co-crystal spheres were studied.The scanning electron microscopy(SEM)results showed that the use of droplet microfluidic technology with the above binders can provide co-crystal microspheres with regular spherical morphology,uniform particle size distribution and good dispersion.X-ray diffraction(XRD),fourier-transform infrared(FT-IR),differential scanning calorimetry(DSC)and thermo-gravimetric(TG)methods were employed to compare the properties of the co-crystal microspheres,raw material and pure co-crystal.The formation of CL-20/TNT co-crystal in the microspheres was confirmed,and the co-crystal microspheres exhibited better thermal stability than the raw material and pure co-crystal.In addition,the mechanical sensitivity and combustion performance of the co-crystal microspheres were further studied.The results showed that the co-crystal microspheres were more insensitive than CL-20 and pure co-crystal,and displayed excellent self-sustained combustion performance and theoretical detonation performance.This study provides a new method for the fast,simple and one-step preparation of CL-20/TNT co-crystal microspheres,with binder coating,uniform particle size distribution,and excellent performance level.

Preparation of reduced sensitivity co-crystals of cyclic nitramines using spray flash evaporation

The present day weapon technology demands novel energetic materials that exhibit simultaneous high explosive yield and reduced sensitivity.This article demonstrates application of spray evaporation to prepare reduced sensitive co-crystals of high performance nitramine explosives like HMX and CL-20 with a relatively less insensitive explosive 1,1-diamino-2,2-dinitroethylene or FOX-7.Stronger intermolecurar hydrogen bonding in FOX-7 is responsible for limited solubility in nost of o rganic solvents.Large solubility differences of FOX-7 with HMX and CL-20 restricts ifs co-crystallization through classical methods that yields thermodynamically favorable product.Spray flash evaporation,a kinetic crystallization method,has been therefore adopted and could successfully produce CL-20/FOX-7(2:1) and HMX/FQX-7(4:1) co-crystals.The fine powdered materials obtained were characterized by SEM,powder XRD,Raman spectro scopy,DSC-TGA etc.Multipoint Raman spectra showed consistent occurrence of spectral features indicating stoichiometric co-existence of ingredients in the crystal lattices.DSC analysis showed absence of all thermally assisted solidsolid phase transformation in the co-crystals as they were observed in pristine materials.The thermal stability calculated in terms of activation barrier fordecomposition,revealed the CL-20/FOX-7 co-crystal to be interlediately stable on comparison to their constituents while,the HMX/FOX-7 co-crystal is more stable.Compared to pure HMX and CL-20,both the co-crystals have shown higher insensitivity to impact force,suggesting them to be suitable for future generation insensitive munitions.

Structure of Co-crystals Formation from Imidazolium and Aromatic Ligands

In this study, two new co-crystals based on rigid imidazolium ligand （2,2＇-（（1,1’- biphenyl）-4,4＇-diyl）bis（2H-imidazo[1,5-a]pyridine-4-ium） hexafluorophosphate （L）） and 4,4＇- bipyridine （Bpy） and benzene （Ben）, formulated as L（Bpy）0.5 （co-crystal 1） and L（Ben） （co-crystal 2）, were obtained. Crystal data for 1： Pī space group with α = 10.921（4）, b = 16.998（6）, c = 17.666（6） A, α = 95.720（7）, β = 104.272（7）, γ = 93.340（6）°, V = 3150.5（19） A^3 and Z = 2; and crystal data for 2： monoclinic C2/m space group with α = 25.90（2）, b = 9.631（9）, c = 6.371（6） A, β = 95.26（2）°, V = 1583（2） A3 and Z = 2. Co-crystal 1 was dependent on hydrogen bonds and π···π stacking, while only hydrogen bonds are present in 2. Two new co-crystals were characterized by IR, NMR spectra, thermogravimetric and ultraviolet absorption analyses.

Non-merohedrally Twinned Crystal Structure of the Co-crystal Ethyl 6-(2-5-(Ethoxycarbonyl)-pyridin-2-yl-1,2-dihydroxyethyl)pyridine-3-carb-oxylateethyl 6-(2-5-(Ethoxycarbonyl)pyridin-2-yl-2-hydroxyacetyl)pyridine-3-carboxylate(0.69/0.31)

The two component molecules of the co-crystal 0.69（C18H2ON206）.0.31（C18H18N2O6） lie on a center-of-inversion that exists midway along the ethylene chain connecting the two aromatic rings. The two molecules are superimposed. The crystal is also a non-morohedral twin with a minor 37.7（2）% component. The refinement of this twinned and disordered crystal structure is detailed. Crystal data： C18H19.38N2O6, monoclinic, P21/c, a = 17.1687（8）, b = 5.4389（2）, c = 9.3261（4） A, b = 95.270（5）° and V= 867.18（6） A3 at -173 ℃.

Synthesis,Crystal Structure and Evaluations of Its Cytotoxicity,Anti-microbial and Anti-hydroxyl Radical Activities of a New Co-crystal Compound(C6H6Cl2N2O2S)·(Phen)·H2O

Co-crystal is a very potential kind of drug solid forms, and has a far-reaching influence on designing and preparing drugs. A new 1：1：1 co-crystal compound consisting of 4-amino-3,5-dichloro-benzenesulfonamide, 1,10-phenanthroline and water was synthesized, and its crystal structure was characterized by X-ray diffraction method. The compositions of the co-crystal are self-assembled into a three-dimensional network structure via intermolecular interactions including hydrogen bonds, π-π stacking, Cl？？？Cl interactions and van der Waals＇ forces. According to the evaluations of cytotoxicity assays, anti-microbial and anti-hydroxyl radicals, this co-crystal is a potential drug.

Theophyllineecitric acid co-crystals easily induced by DSCeFTIR microspectroscopy or different storage conditions

A simultaneous differential scanning calorimetryeFourier transform infrared(DSCeFTIR)microspectroscopy was used to quickly investigate the co-crystal formulation between anhydrous theophylline(TP)and anhydrous citric acid(CA)in a one-step procedure.The raw materials of TP andCA,aswell as the intactTPeCA co-crystal prepared by slow solvent evaporation were also respectively examined by this approach.The result indicates that the TPeCA cocrystal formulation was easily induced using this DSCeFTIR technique.The thermaldependent changes in three-dimensional FTIR spectral contour profiles were started from 165
C to induce the co-crystal formation of TPeCA,which was prior to the endothermic peak at 173
C found in the conventional DSC curve.Beyond 165
C,several new IR absorption peaks at 3515,3124,1730,1710,1677,1648,1552 and 1265 cm1 corresponding to unique IR spectral peaks of intact TPeCA co-crystal were observed.The DSCeFTIR microspectroscopic results also evidenced the dimeremonomer transition of CA,but there were no markedly changes for TP or intact TPeCA co-crystal before its fusion.This strongly implies that the DSCeFTIR technique giving spectroscopic and thermodynamic information could simultaneously induce and identify the TPeCA co-crystal formation and phase transition of samples.Different storage conditions affecting the stability of both physical mixture and ground mixture of TPeCA were also determined.The physicalmixture of TPeCA after storing at 55
C/75%RH condition for one day was fast transformed to TPeCA co-crystal,indicating that TPeCA co-crystal was easily induced under accelerated storage condition.While the co-crystal formed from TPeCA ground mixture was stable in both 25
C/75%RH and 55
C/75%RH conditions.

Synthesis, Structure and Geometrical Calculation of a Novel Co-crystal of {[4-Bromo-2-(benzimidazol-2-yl)phenolato][2-(1-butylbenzimidazol-2-yl)phenolato]zinc(Ⅱ)] and Bis[μ-2-(1-butylbenzimidazol-2-yl)phenolato]-1κN^3:2κO;1κO:2κN^3-bis{[2-(1-butylbe

The title compound has been synthesized and characterized crystallographicaUy. It is a co-crystal consisting of two different neutral zinc（H） complexes with Hbpbm （Hbpbm = 4- bromo-2-（benzimidazol-2-yl）phenol） and Hnpbm （Hnpbm = 2-（1-butylbenzimidazol-2-yl）phenol）. One is a monomeric mixed-ligand complex of [Zn（bpbm）（npbm）] 1 and the other a dimer of [Zn2（npbm）4] 2 with their ratio of 2：1. Thus the overall formula for the title compound is 21.2. Adjacent 1 and 2 are connected to each other by intermolecular hydrogen bonding interactions in the lattice. The crystal data： monoclinic, space group P21/c, a = 15.0141（12）, b = 20.9941（17）, c = 18.4686（15） A, β = 97.445（2）°, V = 5772.4（8） A^3, Mr= 2429.68, Z = 2, Dc = 1.398 g/cm^3,μ = 1.579 -1 mm , F（000） = 2504, R = 0.0637 and wR = 0.1771 for 6464 observed reflections （I 〉 2σ（I））. The geometrical structure for 1 has also been theoretically optimized and compared with the experimental one.

One-dimensional molecular co-crystal alloys capable of full-color emission for low-loss optical waveguide and optical logic gate

The luminescence color of molecule-based photoactive materials is the key to the applications in lighting and optical communication.Realizing continuous regulation of emission color in molecular systems is highly desirable but still remains a challenge due to the individual emission band of purely organic molecules.Herein,a novel alloy strategy based on molecular co-crystals is reported.By adjusting the molar ratio of pyrene(Py)and fluorathene(Flu),three types of molecular co-crystal alloys(MCAs)assemblies are prepared involving Py-Flu-OFN-x%,Py-Flu-TFP-x%,Py-Flu-TCNB-x%.Multiple energy level structure and Förster resonance energy transfer(FRET)process endow materials with tunable full-spectra emission color in visible region.Impressively,these MCAs and co-crystals can be successfully applied to low optical loss waveguide and optical logic gate by virtue of all-color luminescence from blue across green to red,together with smooth surface of onedimensional microrods,which show promising applications as continuous light emitters for advance photonics applications.

Co-crystals of non-steroidal anti-inflammatory drugs(NSAIDs):Insight toward formation,methods,and drug enhancement

Pharmaceutical co-crystals have been explored by many researchers as a strategy to optimize physicochemical properties of solid-state drugs.Their improvements of solubility,bioavailability,and the reduced tendency for phase transformation occurrence,are factors that highlight benefits of pharmaceutical co-crystals among other solid forms.According to the Biopharmaceutical Classification System(BCS),non-steroidal anti-inflammatory drugs(NSAIDs)are class Ⅱ drugs,which have low aqueous solubility and therefore co-crystallization has the potential to optimize NSAID product properties.In this review,we highlight the recent progress made on NSAIDs co-crystals,their co-formers,synthesis,methods and use,while we underline some promising results on in vitro and in vivo co-crystal properties.A celecoxib-tramadol co-crystal reaches phase Ⅲ clinical trials,showing greater analgesic activity than both individual APIs.The aqueous solubility of the co-crystal formed between l-proline and diclofenac is very high in comparison with the pure drug.Naproxen co-crystals with urea and thiourea have an increase of drug release of almost 60%.Co-crystal design brings a new perspective in drug development since the co-former used can also be a biologically active component allowing to combine different anti-inflammatory drugs,which have an incredible spectrum of application due to the analgesic,anti-pyretic and anti-inflammatory properties.

Structural Study on Four co-Crystals of N-Containing Heteroaromatics with Iodofluorobenzene

N-Containing heteroaromatics 1,2,4,5-tetra（pyridin-3-yl）benzene[1,2,4,5-T（3-PY）B] and 1,2,4,5-tetra（pyridin-4-yl）benzene[1,2,4,5-T（4-PY）B] were each co-crystallized with 1,2-diiodo-tetrafluoro-benzene（1,2-DITFB）, or 1,4-diiodo-tetrafluoro-benzene（1,4-DITFB）, respectively, generating four co-crystals, namely, （1,2-DITFB）4 [1,2,4,5-T（3-PY）B]（1）, （1,2-DITFB）4.[ 1,2,4,5-T（4-PY）B]（2）, （1,4-DITFB）2.[1,2,4,5-T（3-PY）B]-CHCI3（3）, and （1,4-DITFB）-[1,2,4,5-T（4-PY）B]2CHCI3（4）. This study takes aim at providing an insight into the relative importance of fundamental solid state halogen bonding interactions（i.e., halogen..N, halogen,..halogen, and halogen...π in systems. The effects of the donor and acceptor on supramolecular assembly and the crystal structure determined interactions were discussed. The N...I halogen bonds are the main directing interactions responsible for the observed structures. In compounds 1 and 2, the donors exhibited lower-than-expected supramolecular connectivity. In spite of this, co-crystal 2 exhibits polymeric structures consisting of infinite one-dimensional（1D） double-zigzag chains of alternating electron donor and acceptor. The basic structure of co-crystals 3 and 4 is also infinite 1D chain. Therefore, the ID halogen bonded supramolecular assemblies can be obtained by matching the appropriate donor and acceptor.

Crystal Engineering of Multiple-component Organic Compound： Organic co-Crystals of the Functional Groups of Carboxyl and Amino with Persistent Hydrogen Bonding Motifs

Three small organic molecular co-crystal compounds （C3N6H6）·（C6H10O4）·H2O（I）, C3HsN2O（3） and （H4btec）2.（4,4＇-bipy）（4）（H4btec=1,2,4,5-benzenetetracarboxylic acid, 4,4＇-bipy=4,4＇-bipyridine） and one coordination supramolecular compound [Mn（CEO4）（HEO）E]＇C6HllNO2（2） were synthesized by hydrothermal reaction. They were characterized by elemental analysis, infrared（IR） spectroscopy and single crystal X-ray diffraction（XRD）. Structural analyses reveal that these 2D or 3D supramolecular networks of the compounds were formed by C--H…O, N--H…O, N--H…N, O--H…O and O-H…N hydrogen bonds. Therein, the functional groups of--COOH, --NH2 and --OH play important roles in constructing supramolecular architectures.

Synthesis, Crystal Structures, Hirshfeld Surfaces, Thermo Characteristics and Solubility of Co-crystal of Buprofezin with Hydrofluoric Acid

A new kind of co-crystal of buprofezin(C(16)H(24)FN3OS) with hydrofluoric acid has been prepared through evaporation technique. It crystallizes in the triclinic space group P1, with a = 9.9733(8), b = 10.3460(9), c = 10.5739(12) ?, a = 68.655(9), b = 73.291(9), g = 66.738(8)o, V = 920.34(17) ?~3, Mr = 325.44, Dc = 1.174 g/cm^3, Z = 2, F(000) = 348, m = 0.190 mm^(-1), the final GOOF = 1.042, R = 0.0485 and wR = 0.1167. Single-crystal X-ray diffraction, XRPD, DSC, TGA, Hirshfeld surface analysis, Raman spectroscopy and FT-IR were used to characterize the co-crystal. It has a twodimensional plane structure, and the intermolecular interactions of co-crystal are mainly H–F×××H, H–O×××H and H–O×××H. Thermology study further confirmed that co-crystal has stronger thermal stability and higher melting point than buprofezin, and it has stronger water solubility. The results show that this co-crystal is valuable for the study of residual activity and application effects of buprofezin.

The antioxidant and physicochemical properties of microencapsulated bioactive compounds in Securigera securidaca(L.)seed extract by co-crystallization

Securigera securidaca seed is a good source of phenolic compounds with high antioxidant properties.Preservation and maintenance of natural antioxidants have always been a challenge and microencapsulation is a suitable method for this purpose.In this study,the chemical compounds of the plant seed extract were identified by GC/MS device.Bioactive compounds from the seed ethanolic extract were microencapsulated in the sucrose matrix during the co-crystallization process.The evaluations included total phenolic compounds,radical scavenging ability,production efficiency,moisture content,and flowability characteristics of the produced powders,such as compressibility index,Hausner ratio,and angle of repose.The results showed significant differences in the phenolic compounds and the radical scavenging ability between the control sample and the co-crystallized powder(P<0.05).The production efficiency and the moisture content of extract-containing co-crystallized powder were 84%and 0.14%,respectively.The particle size difference of the microencapsulated powder could significantly affect the powder flowability characteristics(P<0.05),and particles with a size of 1 mm showed better flowability behaviour.FT-IR charts for samples revealed chemical bonds specific to saccharose molecule indicating no changes in covalent bonds present in saccharose molecule structure after the process.Scanning electron microscope images showed the presence of vacant spaces and porosity in the structure of saccharose crystals formed during the process of crystallization.As a result,the co-crystallized powder obtained from the plant extract can be used as an appropriate antioxidant in the food and pharmaceutical formulations.

Pressure-induced Diels-Alder reactions in C_6H_6—C_6F_6 Co-crystal towards graphane structure

With support from the National Natural Science Foundation of China and the Top 1000-Talents Awards,the research team led by Dr.Zheng HaiYan(郑海燕)and Dr.Li Kuo(李阔)from the Center for High Pressure Science and Technology Advanced Research in Beijing recently synthesized H-F-substituted graphane(H,F-graphane)with a layered structure by compressing 1:1 C6H6-C6F6 co-crystal(abbreviated as CHCF).

Co-crystallization of glycine anhydride with the hydroxybenzoic acids: Controlled formation of dimers via synthons cooperation and structural characterization

The results of crystallographic analyses on 1:1 and 1:4 well-defined co-crystals formed between glycine anhydride and each of 4-hydroxybenzoic acid and 3,5-dihydroxybenzoic acid are described. Neutral molecules are connected via heteromeric O-H···O and N-H···O contacts leading to different packing arrangements of supramolecular chains. On the basis of the molecular structures of glycine anhydride and carboxylic acid guests, the hydrogen bonds are arranged to give centrosymmetric synthons V and VII which are noteworthy for their robustness. Hydrogen-bond interactions between glycine anhydride and aromatic acid provide sufficient driving force to direct molecular recognition and crystal packing. Utilization of the orientation of functional groups of the building blocks, the acidity, and weak interactions provides a route for the creation of novel supra- molecular architectures in the crystal lattice. Both two co-crystals contain the expected hydrogen-bonded motifs, and there has been no proton transfer from either of the two carboxylic acids to the aza compound moiety. This demonstrates that glycine anhydride is very capable of affecting the construction of binary co-crystals in a predictable and rationale manner. It is noted that synthons VⅢ and IX are fairly large, but the real challenge in crystal engineering is to find a big enough synthon that occurs often enough. Thermal stability of these compounds has been investigated by thermogravimetric analysis (TGA) of mass loss.

冲击作用下CL⁃20含能共晶的反应分子动力学模拟

共晶技术是降低六硝基六氮杂异伍兹烷(CL‐20)感度的有效方法之一,研究冲击作用下CL‐20共晶的化学反应,有助于理解CL‐20共晶的冲击反应机制,对炸药安全评价分析具有重要意义。本研究采用ReaxFF‐lg反应力场的分子动力学方法,同时结合非平衡加载方法,对CL‐20/2,5‐二硝基甲苯(DNT)、CL‐20/1,3‐二硝基苯(DNB)和CL‐20/1‐甲基‐3,5‐二硝基‐1,2,4‐三唑(MDNT)三种共晶在2~5 km·s^(-1)冲击速度下的冲击压缩过程进行了分子动力学模拟,获得了含能共晶在冲击作用后的热力学演化特征、初始化学反应路径和产物信息,并与CL‐20的情况进行了对比分析。研究发现:CL‐20/DNT、CL‐20/DNB和CL‐20/MDNT 3种共晶都有一定程度的降低冲击感度作用,3种共晶的冲击感度顺序依次为CL‐20/MDNT>CL‐20/DNB>CL‐20/DNT。3种共晶的分解反应均是从CL‐20分解开始,且CL‐20的分解速度比DNT、DNB和MDNT快。在2 km·s^(-1)冲击速度下,CL‐20共晶首先发生聚合反应,CL‐20与共晶配体分子间的聚合反应早于CL‐20分子间的聚合,且反应频次远高于CL‐20分子之间聚合。在3 km·s^(-1)的冲击条件下,CL‐20首先发生了N—N以及C—N键断裂,笼型结构被破坏,同时生成NO_(2),CL‐20初步断键后的结构及产物NO_(2)会进一步与共晶配体分子DNT、DNB、MDNT结合,降低CL‐20反应中间产物的浓度,达到降感作用。在4,5 km·s^(-1)冲击条件下,CL‐20中的环状骨架结构会直接遭到破坏,发生C—N键断裂,产生小分子碎片,直接生成N2,同时有NO_(2)、H_(2)、CO_(2)、H_(2)O等产物生成。

五角双锥构型的场诱导Co^(Ⅱ)单离子磁体

利用CoCl_(2)·6H_(2)O和2,6-二乙酰吡啶双(氨基脲)(H_(2)dapsc)在水和乙醇的混合溶剂中回流反应得到一例具有五角双锥构型的单核Co~Ⅱ配合物[Co(H_(2)dapsc)(H_(2)O)Cl]Cl·2H_(2)O(1),其中中性的H_(2)dapsc配体分子提供5个配位原子构成其赤道平面,1个水分子和1个Cl^(-)离子则占据其轴向位置,同时在其固态结构中包含1个价态平衡Cl^(-)离子和晶格水分子。直流磁化率研究表明,该配合物具有强的磁各向异性;交流磁性质表明其存在慢磁弛豫行为,直接和拉曼过程同时主导其弛豫,自旋翻转能垒为55.55 K。结合理论计算可以得出,导致该配合物慢磁弛豫行为的主要原因是五角双锥结构的面内各向异性,计算得到的D、E值为45.68、-0.32 cm^(-1)。

硫协同掺杂金刚石单晶的合成

金刚石是目前世界已知物质中集最大硬度、最大热导率、最小压缩率、最宽透光波段、最快声速、抗强酸强碱腐蚀、抗辐射、击穿电压高、载流子迁移率大等多种优异性能于一体的极限性功能材料,广泛应用于工业、科技和国防等领域。掺杂金刚石单晶除具有金刚石本身的优异性能外,还赋予金刚石新的功能特性,引起了科研工作者的广泛关注。硫元素在天然和人工合成金刚石中具有独特的角色,不但其本身可作为合成金刚石的触媒,而且在调配金属触媒特性方面具有独特作用。硫协同掺杂金刚石单晶在调控金刚石内部色心、探索n型金刚石的制备等方面也起着重要作用。文章着重介绍课题组多年来在铁基含硫体系合成工业金刚石单晶,以及硫协同掺杂大尺寸金刚石单晶方面的研究进展。

吲哚美辛共晶和共无定型态固体分散体的研究进展

吲哚美辛是一种经典的非甾体类抗炎药,近年来,吲哚美辛的药理作用在不断扩大,可以用于治疗多种疾病。但存在溶解度差,生物利用度低的问题。共晶和共无定型态固体分散体技术已被广泛应用于提高药物的溶解度和生物利用度。因此,通过对相关文献进行梳理与总结,介绍了吲哚美辛共晶、共无定型态固体分散体、制备方法和表征技术的研究进展。