發(fā)布時間：2018-05-31 01:32

  本文選題：結(jié)構(gòu)相變 + 介電異樣��； 參考：《江蘇科技大學》2017年碩士論文

【摘要】：相變總是伴隨著熱容量的改變,分子或離子的運動,以及結(jié)構(gòu)和電物理性質(zhì)的改變。合成設計新穎的分子基相變材料,不僅是尋找新穎的物理性質(zhì),更是為了更好的研究結(jié)構(gòu)與物理性質(zhì)之間的關(guān)系。為了尋找新型相變材料,我們在閱讀大量相關(guān)文獻的基礎上,選取高對稱性三乙烯二胺配體(Dabco)作為初級配體,并對其進行化學修飾合成了三種基于Dabco的季銨鹽,并以其為構(gòu)筑單元合成八種新穎的相變化合物,并對其相變前后分子結(jié)構(gòu)差異、相變溫度以及介電性質(zhì)進行了研究。1.以[CH_3CH_2-Dabco]~+·Br~-配體為構(gòu)筑單元,通過溶液的緩慢揮發(fā),與過渡金屬離子Zn~(2+)和Co~(2+)自組裝得到三個具有高介電常數(shù)、低介電損耗的金屬-有機配位可逆相變化合物:[CH_3CH_2-Dabco H][ZnCl_4](1);[CH_3CH_2-DabcoH][CoCl_4](2);[CH_3CH_2-DabcoH][ZnBr_4](3);通過變溫X射線單晶衍射儀和差示掃描量熱法(DSC)確定三個化合物都是可逆相變材料;變溫粉末XRD進一步確定了化合物相變的發(fā)生,并且對三個化合物的介電性質(zhì)進行了研究,在相變點附近有著明顯的介電異樣,證明三個化合物都是可逆相變介電材料。DSC掃描結(jié)果表明化合物1,2和3分別在241K,257 K和215 K時發(fā)生相變。變溫單晶結(jié)構(gòu)分析表明三個化合物是同系物,室溫相化合物結(jié)晶在正交晶系Pnma空間群,低溫相結(jié)晶在單斜晶系P21/c空間群。Dabco環(huán)的扭曲以及晶胞內(nèi)分子位置的改變是導致相變發(fā)生的主要原因。2.以[(CH_3)_2CH-Dabco]~+·Br~-配體為構(gòu)筑單元,分別與四氟硼酸鈉和高氯酸通過溶液揮發(fā)法自組裝得到兩個有機分子離子基化合物:[(CH_3)_2CH-DabcoH][Na(BF_4)_3](4);[(CH_3)_2CH-DabcoH][2ClO_4](5);通過變溫X射線單晶衍射儀和差示掃描量熱法確定化合物4是可逆相變材料。DSC掃描結(jié)果表明化合物4在176 K左右時發(fā)生相變,通過在不同溫度時的結(jié)構(gòu)模擬XRD對比確定其發(fā)生了結(jié)構(gòu)相變。變溫單晶結(jié)構(gòu)分析確定在不同溫度時的結(jié)構(gòu),其250 K時結(jié)晶在六方晶系P63空間群,123 K時結(jié)晶在單斜晶系P21/c空間群,同時在相變點附近有并未觀察到明顯的介電異樣,初步判斷可能是分子小角度的轉(zhuǎn)動介電響應相對較弱不易被觀察到。Dabco環(huán)的扭曲以及分子內(nèi)氫鍵的變化是導致相變發(fā)生的主要原因。3.以[CH_3(CH_2)_3-Dabco]~+·Br~-配體為構(gòu)筑單元,分別與過度金屬離子M(M=Zn~(2+),Co~(2+),Ni~(2+))通過溶液揮發(fā)法自組裝得到四個金屬-有機相變化合物: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);通過變溫X射線單晶衍射儀和差示掃描量熱法確定四個化合物都是可逆相變材料;通過在不同溫度時的結(jié)構(gòu)模擬XRD對比確定其發(fā)生了結(jié)構(gòu)相變。DSC掃描結(jié)果表明化合物6,7,8和9分別在186 K,199 K,192 K和194 K左右發(fā)生相變。變溫單晶結(jié)構(gòu)分析確定在不同溫度下的結(jié)構(gòu)表明四個化合物是同系物,室溫相化合物結(jié)晶在正交晶系Pca21空間群,低溫相結(jié)晶在單斜晶系P21空間群。CH_3(CH_2)_3-Dabco配體末端兩個碳原子的無序以及Dabco環(huán)的扭曲是導致相變發(fā)生的主要原因。同時對四個化合物的介電性質(zhì)進行了研究,化合物7在相變溫度附近觀察到可逆介電異樣。
[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.
【學位授予單位】：江蘇科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB34

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