液晶性芳香醛化合物的合成

以对羟基苯甲醛和对烷氧基联苯酰氯为原料,采用爱因宏反应,合成了一系列4-(4'-烷氧基联苯基-4-羧基)苯甲醛.化合物的结构通过元素分析、红外光谱、核磁共振和质谱等方法确证.化合物的液晶行为用示差扫描量热法、偏光显微镜和旋光仪等方法表征.结果表明,所有的化合物加热至各自的熔点以上都能形成液晶态.在液晶态可以观察到手性近晶C相、近晶相、胆甾相和向列相的典型织构.含手性中心的化合物都有较高的旋光性,而且在合成反应中旋光性得到保持.随着分子末端烷氧基碳原子数增加,化合物(除2a和4a外)的熔点(T_m)和液晶态的清亮点(T_i)呈规律性变化,近晶相范围和近晶相-向列相转变温度渐增,而向列相温度范围递减,至十二烷基时,仅呈现近晶性.     

含二苯并-18-冠-6席夫碱型液晶冠醚钾配合物的液晶行为

以顺(反)-4,4′-双[4-(4′-正烷氧基联苯基-4-羧基)苯亚氨基]二苯并-18-冠-6(Ⅰ和Ⅱ)为配体合成了2种系列席夫碱型液晶冠醚钾配合物,产率分别为85.5%～92.1%和88.7%～90.7%。配合物的结构通过元素分析、IR、UV-Vis和AAS等测试技术确证。液晶行为通过DSC、POM、XRD等方法表征。实验结果表明,所有配合物均具有热致液晶性,且随分子末端烷氧基碳原子数增加,其熔点和清亮点呈规律性变化。近晶相温度范围渐增,向列相温度范围递减。与配体相比,配合物液晶态温度范围变宽。     

含二苯并-18-冠-6席夫碱型液晶冠醚钾配合物的合成与表征

以顺(反)-4,4＇-双[4-(4＇-正烷氧基联苯基-4-羧基) 苯亚氨基] 二苯并-18-冠-6（I和II）为配体合成了2个系列席夫碱型液晶冠醚钾配合物,产率分别为85.5%~92.1%和88.7%~90.7%。配合物的结构通过元素分析、IR、UV-Vis和AAS等方法确证。液晶行为通过DSC、POM、XRD等方法表征。实验结果表明,所有配合物均具有热致液晶性,且随分子末端烷氧基碳原子数增加,其熔点和清亮点呈规律性变化。近晶相温度范围渐增,向列相温度范围递减。与配体相比,配合物液晶态温度范围变宽     

新型含氧亚甲基和亚胺桥键的液晶化合物的合成及介晶性

报道一类新的、结构通式为MeO₂CC₆H₄CH₂OC₆H₄CH＝NC₆H₄Y, Y＝OC_nH_2n＋1, Me, Cl, Br, NO₂, H 的棒状液晶化合物的合成. 通过DSC和偏光显微镜对其介晶性研究发现, 除Y＝H外, 这些化合物均具有介晶性. 当Y为非烷氧基时, 呈向列相液晶; 当Y为较短的烷氧基时(n＝1～3), 液晶化合物具有向列相(N); Y为较长烷氧基时(n＝4～16 ), 液晶化合物只有近晶B相(S_B)和近晶A相(S_A); S_A-I相变的熵变随烷氧链原子数而奇-偶变化, 但与N-I相变的“奇-偶效应”相反.     

新型苯甲酸-吡啶超分子液晶的合成: 全氟烃基和介晶体刚性 对液晶性的影响

报道了4-正烷氧基苯甲酸和4-正全氟己基苯甲酸分别与吡啶衍生物3a, 3b通过分子间氢键形成的超分子液晶化合物的合成和热致液晶性. 目标超分子液晶化合物的介晶性和氢键的缔合通过热台偏光显微镜, 差示扫描量热法, 核磁和红外光谱进行了研究. 结果显示: 吡啶衍生物3a, 3b不具有液晶性. 4-正烷氧基苯甲酸与吡啶衍生物3a, 3b形成的复合物4a和4b具有向列相和近晶C相, 而4-全氟己基苯甲酸与吡啶衍生物3a, 3b形成的复合物6a, 6b则呈现多个近晶相. 4a-n系列化合物比4b-n系列具有更高的熔点和清亮点, 而4b-n系列存在明显的奇偶效应. 红外光谱证实了羧基与吡啶基之间存在氢键.     

不对称苯并菲盘状液晶的合成及取代基对介晶性的影响

合成了一系列新型含间位二硝基苯甲酸酯不对称苯并菲盘状液晶化合物2-(3,5-二硝基苯甲酰氧基)-3,6,7,10,11-五烷氧基苯并菲(3a～3f). 通过偏光显微镜(POM)和差示扫描量热计(DSC)对其介晶性进行了研究. 结果显示: 此类化合物有高的清亮点, 稳定的六方柱状相以及较宽的介晶相范围, 且随着软链碳原子数的增加, 化合物的熔点和清亮点均出现下降趋势, 但六方柱状相的有序性却没有发生很明显的变化. 同时通过与其它三类苯并菲盘状液晶2-苯甲酰氧基-3,6,7,10,11-五烷氧基苯并菲(4a～4f), 2-二茂铁甲酰氧基-3,6,7,10,11-五烷氧基苯并菲(5a～5f), 2,3,6,7,10,11-六烷氧基苯并菲(6a～6f)的对比研究, 探讨了酯基, 强吸电子基团, 以及取代官能团体积对介晶性的影响. 证实了苯并菲化合物中分子结构小的变化将引起介晶性大的改变.     

偶氮型液晶冠醚的合成与表征

以4'-正烷氧基联苯-4-甲酸和顺(反)-4,4'-双(4-羟基苯基偶氮)二苯并-14-冠-4为中间体, 通过溶液缩合反应, 合成了一系列偶氮型液晶冠醚. 并用元素分析、核磁共振、紫外可见分光光度计、红外光谱、基质辅助激光解析电离飞行时间质谱、示差扫描量热法和偏光显微镜对其进行了表征. 随分子末端烷氧基碳原子数增加, 化合物4I和4II的熔点(T_m)和液晶态的清亮点(T_i)逐渐降低, 液晶态温度范围较宽.     

含二苯并-18-冠-6和二苯并-14-冠-4的酰胺型液晶冠醚的合成

以4-[(4-正烷氧基联苯基)-4-碳酰氧基]苯甲酸、二氨基二苯并-18-冠-6和二氨基二苯并-14-冠-4为中间体, 通过溶液缩合反应, 合成了两个系列酰胺型液晶冠醚. 并用元素分析、核磁共振、红外光谱、基质辅助激光解析电离飞行时间质谱、示差扫描量热法和偏光显微镜对其进行了表征. 随分子末端烷氧基碳原子数增加, 化合物4I, 4II, 6I和6II的熔点(T_m)和液晶态的清亮点(T_i)逐渐降低, 近晶相范围递增.     

T-型氢键液晶复合物的制备与液晶行为

以不具有液晶行为的2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶(A系列)和4-正烷氧基苯甲酸(D系列)作为氢键液晶复合物的单体,组装成T-型氢键液晶系列复合物(AmDn)。用红外光谱对其结构进行了表征,用DSC及偏光显微方法对其液晶行为进行了研究。结果表明:所合成的21种复合物分子间存在氢键且都具有向列相。通过调整2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子上柔性烷基的长度和极性,可以有效地调节它与4-烷氧基苯甲酸形成的氢键复合物的液晶相变温度以及液晶态的稳定性;增加2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子上柔性烷基的长度,其复合物AmDn的液晶相温度范围趋于变窄,清亮点逐渐下降,其液晶态稳定性也逐渐下降;以2,6-二[N,N′-二-(4-烷基苯甲酰基)]氨基吡啶分子替代2,6-二[N,N′-二-(4-烷氧基苯甲酰基)]氨基吡啶分子,可以降低分子的极性,使其单体的熔点及其氢键复合物AmDn的相变温度下降。     

荧光液晶分子α-氰基二苯乙烯衍生物的合成与光学性质

合成了液晶化合物α-氰基二苯乙烯衍生物(Z)-2-(4-十二烷基氨基苯基)-3-(4-十二烷氧基苯基)丙烯腈（T3）,化合物T3与其同系物(Z)-2-(4-氨基苯基)-3-(4-十二烷氧基苯基)丙烯腈（T2）的浓溶液和固体态在蓝绿光波段均有强的荧光发射。 热重分析数据表明,两个化合物均有好的热稳定性。 利用差式扫描量热分析和偏光显微镜研究了化合物T3的液晶性质,同时借助粉末XRD分析化合物T3的分子间排列方式,表明化合物T3形成近晶相液晶。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.