取代基效應(yīng)調(diào)控的芳香羧酸—疊氮銅分子磁性材料的制備、結(jié)構(gòu)和磁性研究
發(fā)布時(shí)間：2018-08-13 13:19
【摘要】：分子基磁性材料在分子開(kāi)關(guān)、數(shù)據(jù)存儲(chǔ)以及分子水平上的電子設(shè)備等方面有潛在的應(yīng)用,構(gòu)筑高性能分子基磁性材料已成為材料化學(xué)和配位化學(xué)的熱點(diǎn)課題之一。作為橋連配體,疊氮和羧酸不僅是常用的“化學(xué)橋”,而且是優(yōu)秀的“磁學(xué)橋”。本文以疊氮銅體系為研究對(duì)象,引入多種氟取代的芳香羧酸作為輔助配體構(gòu)筑分子基磁性材料,利用取代基效應(yīng)調(diào)控目標(biāo)物的結(jié)構(gòu)和磁性,為制備高性能分子基磁性材料提供理論及實(shí)驗(yàn)指導(dǎo),具體結(jié)果如下:1.采用溶劑熱的反應(yīng)條件,成功構(gòu)筑了一例疊氮銅磁性配合物:[Cu(3-fba)(N3)(C2H5OH)]n(1)(3-fba為3-氟苯甲酸)。通過(guò)X射線結(jié)構(gòu)分析,表明配合物1的最小不對(duì)稱單元包含一個(gè)晶體學(xué)獨(dú)立的Cu(Ⅱ)離子,形成了一個(gè)由三重混橋EO-疊氮、syn,syn-羧酸和μ2-乙醇構(gòu)成的1D銅鏈。磁性測(cè)試表明,目標(biāo)配合物是由鐵磁相互作用的鐵磁鏈組成的,其中Cu-N-Cu鍵角是105.95°。出現(xiàn)在配合物1相鄰銅離子之間明顯的磁耦合是由于多重超交換途徑的反補(bǔ)償效應(yīng)引起的,導(dǎo)致了鐵磁有序(Tc=11.0 K)和慢磁馳豫,在大多數(shù)疊氮銅配合物中很少被發(fā)現(xiàn)。熱容測(cè)試進(jìn)一步證明了長(zhǎng)程磁有序特征。另外,通過(guò)DFT計(jì)算對(duì)1中銅離子間的鐵磁耦合作用進(jìn)行了深入的研究。2.選取含有不同數(shù)量氟原子取代基的苯甲酸衍生物:2-氟苯甲酸和2,6-二氟苯甲酸作為輔助配體,成功合成了兩例新穎的疊氮銅配合物:[Cu(2-fba)(N3)(CH3OH)]n(2)和[Cu(2,6-dfba)(N3)(CH3OH)]n(3)(2-Hfba 為 2-氟苯甲酸和 2,6-Hdfba 為 2,6-二氟苯甲酸),對(duì)其結(jié)構(gòu)和磁性進(jìn)行了研究。單晶結(jié)構(gòu)分析表明,兩個(gè)目標(biāo)配合物中的金屬離子是由交替的三重橋μ-1,1-疊氮,syn,syn-羧酸和μ2-甲醇分子連接起來(lái),構(gòu)成了相似的線性一維銅鏈結(jié)構(gòu),而鏈內(nèi)鏈間的結(jié)構(gòu)參數(shù)略有不同。微調(diào)的結(jié)構(gòu)導(dǎo)致了兩個(gè)目標(biāo)配合物不同的磁性。盡管兩個(gè)配合物鏈內(nèi)相鄰的銅離子間強(qiáng)的鐵磁耦合均由多重橋的超交換作用導(dǎo)致的反補(bǔ)償效應(yīng)產(chǎn)生,然而有趣的磁有序和慢磁弛豫只出現(xiàn)在配合物2中,這種特點(diǎn)在大多數(shù)已報(bào)道的疊氮銅配合物中很少出現(xiàn),并且,配合物3表現(xiàn)出由鐵磁耦合的銅鏈構(gòu)成的反鐵磁體的特征。熱容測(cè)試進(jìn)一步證明了配合物2的長(zhǎng)程磁有序特性和配合物3的反鐵磁體行為。此外,DFT計(jì)算從理論上定性解釋了兩個(gè)配合物的磁行為。3.基于兩種同分異構(gòu)的氟取代苯乙酸:鄰氟苯乙酸和對(duì)氟苯乙酸,制備了兩例疊氮銅配合物[Cu(o-fpa)(N3)(C2H5OH)]n(4)和[Cu(p-fpa)(N3)(C2H5OH)]n(5)(o-fpa為鄰-氟苯乙酸,p-fpa為對(duì)-氟苯乙酸)。單晶結(jié)構(gòu)分析表明配合物4和5是由1D鏈狀配位圖案組成,其中相鄰銅離子是由交替的三重橋μ-1,1-疊氮,syn,syn-羧酸和μ2-乙醇連接起來(lái)。在兩個(gè)配合物中,由兩個(gè)苯乙酸輔助配體不同的取代基效應(yīng)造成的羧基上不同的電荷分布導(dǎo)致了鏈內(nèi)Cu-Cu距離和Cu-N-Cu鍵角等結(jié)構(gòu)參數(shù)的不同,引起了磁行為的不同。兩個(gè)配合物相鄰銅離子間強(qiáng)的鐵磁耦合(J= 87.08 cm-1對(duì)于4,J= 66.05 cm-1對(duì)于5)是由多重超交換途徑的反補(bǔ)償效應(yīng)引起的,使兩個(gè)化合物中出現(xiàn)了鐵磁有序(Tc=11.0K對(duì)于4,9.5K對(duì)于5)和慢磁弛豫行為,這類現(xiàn)象在已報(bào)道的疊氮銅配合物中較為罕見(jiàn)。熱容測(cè)試進(jìn)一步證明了配合物4和5的長(zhǎng)程磁有序。進(jìn)一步探究了兩個(gè)化合物的磁構(gòu)關(guān)系。此外,DFT計(jì)算對(duì)兩個(gè)配合物中銅離子間的鐵磁耦合作用做了進(jìn)一步的闡明。
[Abstract]:Molecular-based magnetic materials have potential applications in molecular switching, data storage and electronic devices at the molecular level. Building high-performance molecular-based magnetic materials has become one of the hot topics in material chemistry and coordination chemistry. As bridging ligands, azide and carboxylic acids are not only common "chemical bridges" but also excellent "magnetic bridges". In this paper, a variety of fluorine-substituted aromatic carboxylic acids are introduced as auxiliary ligands to construct molecular-based magnetic materials, and the substituent effect is used to control the structure and magnetism of the target compounds, which provides theoretical and experimental guidance for the preparation of high-performance molecular-based magnetic materials. The specific results are as follows: 1. Solvothermal reaction. A magnetic copper azide complex, [Cu (3-fba) (N3) (C2H5OH)] n (1) (3-fba 3-fluorobenzoic acid) was successfully constructed. X-ray structural analysis showed that the smallest asymmetric unit of complex 1 contained a crystallographically independent Cu (II) ion, forming a 1D copper chain consisting of triple mixed bridged EO-azide, syn, syn-carboxylic acid and mu 2-ethanol. Magnetic measurements show that the target complex is composed of ferromagnetic interacting ferromagnetic chains with a Cu-N-Cu bond angle of 105.95 degrees. The apparent magnetic coupling between adjacent copper ions in complex 1 is due to the anti-compensation effect of multiple superexchange pathways, resulting in ferromagnetic ordering (Tc=11.0 K) and slow magnetic relaxation in most copper azide. Ferromagnetic coupling between copper ions in 1 was studied by DFT calculation. 2. Benzoic acid derivatives containing different amounts of fluorine atom substituents, 2-fluorobenzoic acid and 2,6-difluorobenzoic acid, were selected as auxiliary ligands. Two novel copper azide complexes, [Cu (2-fba) (N3) (CH3OH)] n (2) and [Cu (2,6-dfba) (N3) (CH3OH)] n (3) (2-Hfba is 2-fluorobenzoic acid and 2,6-Hdfba is 2,6-difluorobenzoic acid) have been synthesized and their structures and magnetic properties have been studied. The single crystal structure analysis shows that the metal ions in the two target complexes are triple-bridged mu-1,1-superimposed. Nitrogen, syn, syn-carboxylic acid and mu 2-methanol molecules are linked to form a similar linear one-dimensional copper chain structure with slightly different structural parameters between the inner chains. The fine-tuned structure results in different magnetic properties of the two target complexes. Although the strong ferromagnetic coupling between adjacent copper ions in the two complex chains is conducted by the superexchange of multiple bridges. However, interesting magnetic ordering and slow magnetic relaxation occur only in complex 2, which is rarely seen in most reported copper azide complexes, and complex 3 exhibits the characteristics of an antiferromagnet consisting of ferromagnetic coupling copper chains. In addition, DFT calculations qualitatively explain the magnetic behavior of the two complexes. 3. Two copper azide complexes [Cu (o-fpa) (N3) (C2H5OH)] n (4) and [Cu (p-fpa) (N3) (C2H5OH)] n (5) (o-fpa) were prepared based o n two isomeric fluorophenylacetic acids: o-fluorophenylacetic acid and p-fluorophenylacetic acid. Fluorophenylacetic acid, p-fpa, p-fluorophenylacetic acid). Single crystal structure analysis shows that complexes 4 and 5 are composed of 1D chain-like coordination patterns, in which adjacent copper ions are linked by alternating triple bridges of mu-1,1-azide, syn, syn-carboxylic acid and mu 2-ethanol. In the two complexes, carboxylic acid is caused by the different substituent effects of two phenylacetic acid auxiliary ligands. The strong ferromagnetic coupling (J = 87.08 cm-1 to 4, J = 66.05 cm-1 to 5) between the adjacent copper ions of the two complexes is caused by the inverse compensation effect of multiple super-exchange pathways. Ferromagnetic ordering (Tc = 11.0K for 4,9.5K for 5) and slow magnetic relaxation behavior have been investigated. These phenomena are rare in reported copper azide complexes. The long-range magnetic ordering of complexes 4 and 5 has been further confirmed by heat capacity measurements. The magnetic structure relationship between the two complexes has been further explored. In addition, the ferromagnetism between copper ions in the two complexes has been calculated by DFT. The coupling effect is further elucidated.
【學(xué)位授予單位】：寧夏大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O641.4
本文編號(hào)：2181119
[Abstract]:Molecular-based magnetic materials have potential applications in molecular switching, data storage and electronic devices at the molecular level. Building high-performance molecular-based magnetic materials has become one of the hot topics in material chemistry and coordination chemistry. As bridging ligands, azide and carboxylic acids are not only common "chemical bridges" but also excellent "magnetic bridges". In this paper, a variety of fluorine-substituted aromatic carboxylic acids are introduced as auxiliary ligands to construct molecular-based magnetic materials, and the substituent effect is used to control the structure and magnetism of the target compounds, which provides theoretical and experimental guidance for the preparation of high-performance molecular-based magnetic materials. The specific results are as follows: 1. Solvothermal reaction. A magnetic copper azide complex, [Cu (3-fba) (N3) (C2H5OH)] n (1) (3-fba 3-fluorobenzoic acid) was successfully constructed. X-ray structural analysis showed that the smallest asymmetric unit of complex 1 contained a crystallographically independent Cu (II) ion, forming a 1D copper chain consisting of triple mixed bridged EO-azide, syn, syn-carboxylic acid and mu 2-ethanol. Magnetic measurements show that the target complex is composed of ferromagnetic interacting ferromagnetic chains with a Cu-N-Cu bond angle of 105.95 degrees. The apparent magnetic coupling between adjacent copper ions in complex 1 is due to the anti-compensation effect of multiple superexchange pathways, resulting in ferromagnetic ordering (Tc=11.0 K) and slow magnetic relaxation in most copper azide. Ferromagnetic coupling between copper ions in 1 was studied by DFT calculation. 2. Benzoic acid derivatives containing different amounts of fluorine atom substituents, 2-fluorobenzoic acid and 2,6-difluorobenzoic acid, were selected as auxiliary ligands. Two novel copper azide complexes, [Cu (2-fba) (N3) (CH3OH)] n (2) and [Cu (2,6-dfba) (N3) (CH3OH)] n (3) (2-Hfba is 2-fluorobenzoic acid and 2,6-Hdfba is 2,6-difluorobenzoic acid) have been synthesized and their structures and magnetic properties have been studied. The single crystal structure analysis shows that the metal ions in the two target complexes are triple-bridged mu-1,1-superimposed. Nitrogen, syn, syn-carboxylic acid and mu 2-methanol molecules are linked to form a similar linear one-dimensional copper chain structure with slightly different structural parameters between the inner chains. The fine-tuned structure results in different magnetic properties of the two target complexes. Although the strong ferromagnetic coupling between adjacent copper ions in the two complex chains is conducted by the superexchange of multiple bridges. However, interesting magnetic ordering and slow magnetic relaxation occur only in complex 2, which is rarely seen in most reported copper azide complexes, and complex 3 exhibits the characteristics of an antiferromagnet consisting of ferromagnetic coupling copper chains. In addition, DFT calculations qualitatively explain the magnetic behavior of the two complexes. 3. Two copper azide complexes [Cu (o-fpa) (N3) (C2H5OH)] n (4) and [Cu (p-fpa) (N3) (C2H5OH)] n (5) (o-fpa) were prepared based o n two isomeric fluorophenylacetic acids: o-fluorophenylacetic acid and p-fluorophenylacetic acid. Fluorophenylacetic acid, p-fpa, p-fluorophenylacetic acid). Single crystal structure analysis shows that complexes 4 and 5 are composed of 1D chain-like coordination patterns, in which adjacent copper ions are linked by alternating triple bridges of mu-1,1-azide, syn, syn-carboxylic acid and mu 2-ethanol. In the two complexes, carboxylic acid is caused by the different substituent effects of two phenylacetic acid auxiliary ligands. The strong ferromagnetic coupling (J = 87.08 cm-1 to 4, J = 66.05 cm-1 to 5) between the adjacent copper ions of the two complexes is caused by the inverse compensation effect of multiple super-exchange pathways. Ferromagnetic ordering (Tc = 11.0K for 4,9.5K for 5) and slow magnetic relaxation behavior have been investigated. These phenomena are rare in reported copper azide complexes. The long-range magnetic ordering of complexes 4 and 5 has been further confirmed by heat capacity measurements. The magnetic structure relationship between the two complexes has been further explored. In addition, the ferromagnetism between copper ions in the two complexes has been calculated by DFT. The coupling effect is further elucidated.
【學(xué)位授予單位】：寧夏大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O641.4
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