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本文合成了一系列含有胆固醇和4-(反式-正烷基环己基)苯甲酸结构单元的新型双液晶基元液晶化合物。这些化合物中两个介晶基元是利用不同长度的氧烷酰基连接在一起。利用FT-IR、MS、1H NMR、POM、DSC 表证了所得化合物的结构和介晶性,并选择几种双液晶基元液晶测定了它们的机械黏度和在主体液晶中的螺旋扭曲力(HTP)。结果表明,绝大多数化合物显示较低相变温度的胆甾相(N*),并且被选择的化合物的平均机械黏度和螺旋扭曲力类似于或优于胆甾醇任酸酯。 相似文献
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反-4-(反-4′-丙基环己基)环己基甲酸的新合成方法 总被引:1,自引:0,他引:1
环己烷类液晶具有较高的相变温度和较低的粘度,克服了目前仍广泛使用的联苯类液晶相变温度低、粘度大、响应速度较慢的缺点,这类液晶材料已日益成为中高档混合液晶材料不可缺少的有效组分[1]. 反-4-(反-4′-丙基环己基)环己基甲酸(trans-3HHA)是合成这类液晶材料很重要的中间体,因此,它的合成具有重要应用价值. Trans-3HHA合成需经2步反应:加氢和异构化. 加氢反应以4-(反-4′-丙基环己基)苯甲酸(3HPA)为反应物,在加氢催化剂存在下,生成包含trans-3HHA和顺-4-(反-4′-丙基环己基)环己基甲酸(cis-3HHA)2种异构体的混合物(合称3HHA). 其中反式异构体trans-3HHA含量很低,必须进行异构化反应,使cis-3HHA转变为trans-3HHA. 文献报道有几种方法,如顺式或顺反-4-烷基环己基甲酸混合物在盐酸水溶液[2]、氢化钠乙醇溶液[3]和氢氧化钠水溶液[4]中,加热进行异构化反应. 但得到的产物反式与顺式异构体质量比都在75∶ 25~85∶ 15之间,需经多次重结晶才能得到反式异构体,产率低于70%. 本文以氢氧化钾为催化剂,加氢产物3HHA在无溶剂的条件下进行异构化,产物反式与顺式异构体质量比达到98∶ 2,产率>90%. 相似文献
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LIU Si-jie NIU Ya-ming ZHU Xiao-liang WANG Gui-bin JIANG Zhen-hua 《高等学校化学研究》2006,22(1):114-117
IntroductionPoly(aryl ether ketone)s are high performance en-gineering plastics with outstanding physical,chemical,thermal and mechanical properties and have been ap-plied to the aerospace industry,the electronic industry,the automobile industry,the petro… 相似文献
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A new dinuclear complex [Tb2(BA)6(2,2′-bipy)2] (BA=4-(trifluoromethyl)benzoic acid, 2,2′-bipy=2,2′-bipyridine) has been synthesized. The complex was characterized by X-ray single-crystal structure analysis. The complex is a dimer with an inversion center. In the complex, two Tb3+ ions are linked by four carboxylate groups of BA ligands in bridging-bidentate coordination mode. Each Tb3+ ion is eight-coordinated with two nitrogen atoms from one 2,2′-bipy molecule, four oxygen atoms from four bridging-bidentate BA ligands and two oxygen atoms from one chelating-bidentate BA ligand. Intermolecular hydrogen bonds are formed in the crystal. The complex exhibits strong green fluorescence under ultraviolet light and the fluorescence spectrum consists of four lines peaking at 489, 545, 584 and 620 nm, which are corresponding to the 5D4→7Fj (j=6~3) transitions of Tb3+ ion, respectively. CCDC: 727763. 相似文献
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Hong Zhou GAO Wei Lin SUN Zhi Quart SHEN 《中国化学快报》2005,16(8):1113-1116
A new polyamide containing bithiazole moieties (PTA) was synthesized by the polycondensation of 2, 2'-diamino-4, 4'-bithiazole (DABT) and oxalyl chloride. The polymer complex was prepared from PTA and NdC13 in DMSO. They were characterized through IR and elemental analysis. The preliminary magnetic properties of the complex PTA-Nd^3+ was investigated, it was found that the material is a ferromagnet at low temperature. 相似文献
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Russian Journal of Organic Chemistry - Some new derivatives of six-membered heterocyclic compounds containing isoniazid and nicotinic acid hydrazide fragments have been synthesized according to... 相似文献
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聚醚醚酮(PEEK)是英国ICI公司开发成功的结晶性热塑型耐高温工程塑料,具有许多优良性能,其玻璃化转变温度高达143℃,大量应用于电气、电子、机械、医疗、食品及航天航空领域[1,2].只溶于浓硫酸,不溶于普通溶剂,使应用范围受到一定的限制.酚酞型聚... 相似文献
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将可交联的苯乙炔结构引入到热塑性聚芳醚酮链中, 并对其交联前后的性能进行了深入研究. 相似文献
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Chamathka Dehiwala Liyanage José J. Ortiz-Garcia Annalena Struckmeier Dr. Michael Kienzler Dr. Rebecca C. Quardokus 《Chemphyschem》2023,24(17):e202300160
Photochromic molecules can undergo a reversible conversion between two isomeric forms upon exposure to external stimuli such as electromagnetic radiation. A significant physical transformation accompanying the photoisomerization process defines them as photoswitches, with potential applications in various molecular electronic devices. As such, a detailed understanding of the photoisomerization process on surfaces and the influence of the local chemical environment on switching efficiency is essential. Herein, we use scanning tunneling microscopy to observe the photoisomerization of 4-(phenylazo)benzoic acid (PABA) assembled on Au(111) in kinetically constrained metastable states guided by pulse deposition. Photoswitching is observed at low molecular density and is absent in tight-packed islands. Furthermore, switching events were noted in PABA molecules coadsorbed in a host octanethiol monolayer, suggesting an influence of the surrounding chemical environment on photoswitching efficiency. 相似文献
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在乙醇体系中,由主配体4-[(1,3-二氧代丁基)氨基]苯甲酸(H2L,C11H11NO4)、稀土硝酸盐及辅助配体邻菲啰啉(phen)反应合成了两个系列8个配合物[Ln2(L)3(H2O)4]n(Ln=Sm(1),Eu(2),Tb(3),Dy(4));[Ln2(NO3)2(L)2(phen)2]n(Ln=Sm(5),Eu(6),Tb(7),Dy(8))。用元素分析、红外光谱、摩尔电导、热重分析进行表征,确定了产物的化学组成,推断了相应的结构。测定了室温时固体产物的激发和发射光谱,结果表明:由主辅配体共同配位的三元配合物的发光强度好于无辅助配体参与的二元配合物。测定了三元配合物的荧光寿命,其中铕和铽配合物显示较长的荧光寿命。 相似文献
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以4-碘-L-苯丙氨酸为初始原料,先将羧基和氨基进行保护、后与苯乙烯进行Heck反应,最后在碱性和酸性条件下脱除保护合成二苯乙烯氨基酸,即(E)-2-氨基-3-(4-苯乙烯基苯基)丙酸的盐酸盐(4),产率53.7%,其结构经1H NMR、 IR和HR-MS(ESI-TOF)表征。光学性质研究结果表明:4的激发波长为312 nm,发射波长为357 nm,斯托克斯位移为45 nm,荧光量子产率为0.09。 4在甲醇溶液中存在光致顺反异构现象,反式→顺式结构转变速率常数为0.046 min-1。 相似文献
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以辣素功能结构单体N-(4-羟基-3-甲氧基-苄基)-丙烯酰胺(HMBA)为疏水单体,与丙烯酰胺(AM)和2-丙烯酰胺基-2-甲基丙磺酸钠(NaAMPS)通过自由基胶束共聚,制得三元疏水缔合聚合物P(AM-NaAMPS-HMBA)(简称PAAH). 采用紫外-可见光谱、核磁共振氢谱、热重分析及扫描电子显微镜对共聚物的结构及形貌进行表征,利用原子力显微镜对聚合物水溶液的微观形貌进行观察,并对其溶解性、疏水缔合性、耐温性及抑菌性能进行了研究. 结果表明,所得共聚物中疏水单体含量与投料比基本一致;PAAH具有良好的速溶性,当聚合物浓度超过一定值后,溶液黏度急剧增加,且随着疏水单体含量增加,疏水缔合性能增强;原子力显微镜观察证实了聚合物水溶液中网络结构的存在. 与未改性的P(AM-NaAMPS)(简称PAA)共聚物相比,引入具有生物活性且带有刚性苯环结构的HMBA单体可使PAAH共聚物热稳定性增强,耐温性能提高,并赋予其优良的抑菌性能. 相似文献
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Riichiro Nakajima Takashi Ise Yoshiyuki Takahashi Hideo Yoneda Kanya Tanaka Tadashi Hara 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):535-536
Abstract Three 4-(oligothienyl)pyridines and four α,ω-di(4-pyridyl)oligo-thiophenes were prepared and the effect of conjugated thiophene rings on their fluorescence properties were examined. 4-(2,2′-Bithienyl-5-yl)pyridine and 2,5-di(4-pyridyl)thiophene exhibited laser dye emission upon pumping with a nitrogen laser and the conversion efficiency of the latter was 1.5 times as great as that of a commercial laser dye PBBO at 400 nm. 相似文献