三乙烯二胺衍生物诱导合成分子基相变材料及其介电性质的研究

发布时间：2018-05-31 01:32

本文选题：结构相变 + 介电异样　；参考：《江苏科技大学》2017年硕士论文

【摘要】：相变总是伴随着热容量的改变,分子或离子的运动,以及结构和电物理性质的改变。合成设计新颖的分子基相变材料,不仅是寻找新颖的物理性质,更是为了更好的研究结构与物理性质之间的关系。为了寻找新型相变材料,我们在阅读大量相关文献的基础上,选取高对称性三乙烯二胺配体(Dabco)作为初级配体,并对其进行化学修饰合成了三种基于Dabco的季铵盐,并以其为构筑单元合成八种新颖的相变化合物,并对其相变前后分子结构差异、相变温度以及介电性质进行了研究。1.以[CH_3CH_2-Dabco]~+·Br~-配体为构筑单元,通过溶液的缓慢挥发,与过渡金属离子Zn~(2+)和Co~(2+)自组装得到三个具有高介电常数、低介电损耗的金属-有机配位可逆相变化合物:[CH_3CH_2-Dabco H][ZnCl_4](1);[CH_3CH_2-DabcoH][CoCl_4](2);[CH_3CH_2-DabcoH][ZnBr_4](3);通过变温X射线单晶衍射仪和差示扫描量热法(DSC)确定三个化合物都是可逆相变材料;变温粉末XRD进一步确定了化合物相变的发生,并且对三个化合物的介电性质进行了研究,在相变点附近有着明显的介电异样,证明三个化合物都是可逆相变介电材料。DSC扫描结果表明化合物1,2和3分别在241K,257 K和215 K时发生相变。变温单晶结构分析表明三个化合物是同系物,室温相化合物结晶在正交晶系Pnma空间群,低温相结晶在单斜晶系P21/c空间群。Dabco环的扭曲以及晶胞内分子位置的改变是导致相变发生的主要原因。2.以[(CH_3)_2CH-Dabco]~+·Br~-配体为构筑单元,分别与四氟硼酸钠和高氯酸通过溶液挥发法自组装得到两个有机分子离子基化合物:[(CH_3)_2CH-DabcoH][Na(BF_4)_3](4);[(CH_3)_2CH-DabcoH][2ClO_4](5);通过变温X射线单晶衍射仪和差示扫描量热法确定化合物4是可逆相变材料。DSC扫描结果表明化合物4在176 K左右时发生相变,通过在不同温度时的结构模拟XRD对比确定其发生了结构相变。变温单晶结构分析确定在不同温度时的结构,其250 K时结晶在六方晶系P63空间群,123 K时结晶在单斜晶系P21/c空间群,同时在相变点附近有并未观察到明显的介电异样,初步判断可能是分子小角度的转动介电响应相对较弱不易被观察到。Dabco环的扭曲以及分子内氢键的变化是导致相变发生的主要原因。3.以[CH_3(CH_2)_3-Dabco]~+·Br~-配体为构筑单元,分别与过度金属离子M(M=Zn~(2+),Co~(2+),Ni~(2+))通过溶液挥发法自组装得到四个金属-有机相变化合物:Zn[CH_3(CH_2)_3-Dabco]Cl_(2.5)Br_(0.5)(6);Co[CH_3(CH_2)_3-Dabco]Cl2.6Br0.4(7);Ni[CH_3(CH_2)_3-Dabco]Cl_(2.5)Br_(0.5)(8);Zn[CH_3(CH_2)_3-Dabco]Br_3(9);通过变温X射线单晶衍射仪和差示扫描量热法确定四个化合物都是可逆相变材料;通过在不同温度时的结构模拟XRD对比确定其发生了结构相变。DSC扫描结果表明化合物6,7,8和9分别在186 K,199 K,192 K和194 K左右发生相变。变温单晶结构分析确定在不同温度下的结构表明四个化合物是同系物,室温相化合物结晶在正交晶系Pca21空间群,低温相结晶在单斜晶系P21空间群。CH_3(CH_2)_3-Dabco配体末端两个碳原子的无序以及Dabco环的扭曲是导致相变发生的主要原因。同时对四个化合物的介电性质进行了研究,化合物7在相变温度附近观察到可逆介电异样。
[Abstract]:The phase transition is always accompanied by changes in thermal capacity, movement of molecules or ions, and changes in structure and physical and physical properties. The synthesis of novel molecular based phase change materials is not only to find new physical properties, but also to better study the relationship between structure and physical properties. In order to find a new phase change material, we are reading a lot. Based on the relevant literature, the high symmetry three ethylene two amine ligand (Dabco) was selected as the primary ligand, and three kinds of quaternary ammonium salts based on Dabco were synthesized by chemical modification, and eight novel phase transition compounds were synthesized by the construction unit, and the molecular structure difference, phase transition temperature and dielectric properties of the phase transition were carried out. The study of.1. with [CH_3CH_2-Dabco]~+ / Br~- ligand as the building unit, through the slow volatilization of solution, with the transition metal ions Zn~ (2+) and Co~ (2+) self-assembled to get three high dielectric constant, low dielectric loss of metal organic coordination reversible phase transition compounds: [CH_3CH_2-Dabco H][ZnCl_4] (1); [CH_3CH_2-DabcoH][CoCl_4] (2); [CH_3CH_2-Dabc, [CH_3CH_2-Dabc. OH][ZnBr_4] (3); three compounds are reversible phase change materials determined by variable temperature X ray single crystal diffractometer and differential scanning calorimetry (DSC); variable temperature powder XRD further determines the phase transition of compounds, and the dielectric properties of three compounds are studied. There are obvious dielectric anomalies near the phase transition point, which prove that three chemical compounds are changed. The.DSC scanning results of the reversible phase transition dielectric materials show that the phase transition of compound 1,2 and 3 at 241K, 257 K and 215 K respectively. The crystal structure analysis shows that the three compounds are homologues, the room temperature phase compounds crystallized in the Pnma space group of the orthogonal crystal system, and the cryogenic phase crystallized in the distortion and crystal of the.Dabco ring of the P21/c group of monoclinic system P21/c group. The change in the location of the intracellular molecules is the main cause of the phase transition,.2. (CH_3) _2CH-Dabco]~+ / Br~- ligand as the building unit, and two organic ionic radical compounds are obtained by self assembly of sodium tetrafluoroborate and perchloric acid through the solution volatilization method: [(CH_3) _2CH-DabcoH][Na (BF_4) _3] (4); [(CH_3) _2CH-DabcoH][2ClO_4] (5); The temperature variable X ray single crystal diffractometer and differential scanning calorimetry determine that compound 4 is a reversible phase change material.DSC scanning result indicating that the phase transition of compound 4 at about 176 K occurs. The structural phase transition of the compound is determined by the structural simulation of XRD at different temperatures. The structure of the single crystal structure at different temperatures is determined at different temperatures and at 250 K. The crystallization is in the six square crystal system P63 space group, and the crystallization is in the monoclinic P21/c space group at 123 K. At the same time, there is no apparent dielectric anomaly near the phase transition point. It is possible to judge that the rotational dielectric response of the small angle is relatively weak and is not easily observed in the distortion of the.Dabco ring and the change of the intramolecular hydrogen bond is the result of the phase transition. The main reason.3. is [CH_3 (CH_2) _3-Dabco]~+ / Br~- ligand as the building unit, and the four metal organic phase transition compounds are self assembled by solution volatilization, respectively, M (M=Zn~ (2+), Co~ (2+), Ni~ (2+)), respectively. (2.5) Br_ (0.5) (0.5) (8); Zn[CH_3 (CH_2) _3-Dabco]Br_3 (9); the four compounds are reversible phase change materials determined by the variable temperature X ray single crystal diffractometer and differential scanning calorimetry; the structural phase change.DSC scanning results are determined by the structure simulation XRD contrast at different temperatures indicating that the compounds 6,7,8 and 9 are in 186 K, 199 K, 192 K, respectively. The structure analysis of the single crystal structure at 194 K shows that the structure at different temperatures indicates that four compounds are homologues, the room temperature phase compounds crystallized in the Pca21 space group of the orthonormal system, and the low temperature phase crystallized in the disorder of two carbon atoms at the end of the P21 space group.CH_3 (CH_2) _3-Dabco ligand in the monoclinic system and the distortion of the Dabco ring. Meanwhile, the dielectric properties of the four compounds were studied. The reversible dielectric anomaly of compound 7 was observed near the transition temperature.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB34

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