1,1-二氨基-2,2-二硝基乙烯的晶型研究

The Polymorphy of 1,1-Diamino-2,2-Dinitroethylene

采用四圆衍射仪对培养的1,1-二氨基-2,2-二硝基乙烯(简称FOX-7)单晶进行测试,结构解析结果:晶体属单斜晶系,空间群P21/n,a=0.69283 nm,b=0.66201 nm,c=1.13230 nm,α=89.948°,β=90.533°,γ=89.894°,V=0.5193 nm3,Dx=1.893g.cm-3,Z=4,F(000)=304。FOX-7分子呈层状构型,分子内存在大量的氢键,分子间依靠范德华力结合。利用变温X射线衍射仪得到了FOX-7在加热时的相变,结果发现了两个相变温度点,获得了α、β、γ三相的衍射图,并且确定了α和β相的晶胞参数。此外当温度降低时,γ相可以不经过β相直接转变成α相,只是需要的时间较长。

The single crystal of 1,1 - diamino - 2,2 - dinitroethylene was measured by the tetracyclic diffractometer. The crystal has monoclinic P21/n symmetry with a =0.69283 nm,b =0.66201 nm,c =1. 13230 nm,α =89.948°,β = 90. 533°,γ =89. 894° ,V=0. 5193 nm^3 ,Dx = 1. 893 g · cm^-3 ,Z =4,F（000） =304. The results indicated that the molecular arrangement inside the crystal is two-dimensional wave-shaped layers, with extensive intermolecular hydrogen bonding within the layers and with simple van der Waals interaction between the layers. The phase transitions of FOX - 7 was tested by temperature controlled X-ray power diffraction （XRD） when FOX - γ had been heated. It was found that there are two temperature dependent phase transitions, and the XRD patterns of α-phase,β- phase,γ-phase were obtained. When the temperature decreases, α-phase can directly change to β-phase.