低温制备具有强荧光性能三氧化钼纳米带水溶胶

通过过氧化途径,在低温(100℃)且不使用模板和有机溶剂的条件下,成功制备了具有良好荧光性能的三氧化钼(MoO3)纳米带水溶胶.利用X射线衍射仪(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HRTEM)、荧光光谱仪、荧光显微镜等表征手段对所制备溶胶的结构及性能进行了表征.结果显示,溶胶是由长度约为100μm,宽度为50nm到100nm,厚度小于10nm的MoO3纳米带组成.所制备的溶胶烘干后可以得到大面积的MoO3纳米带薄膜,薄膜具有很好的韧性.荧光光谱图及荧光显微镜照片显示,纳米带溶胶及干燥后所得到的自支撑(free standing)纳米带薄膜均具有良好的荧光性能,表明其在光学成像、传感及LED等方面具有很好的应用前景.     

基于新疆煤炭的荧光碳量子点的制备与应用研究

本实验以新疆五种不同产地的煤炭为原料,采用酸煮回流法分别制备了五种碳量子点(CQDs)。通过荧光光谱对比分析,巴里坤煤样所制备的CQDs荧光性能最佳。利用透射电子显微镜(TEM)、X射线衍射光谱(XRD)、傅里叶变化红外光谱(FTIR)、紫外可见吸收光谱(UV/vis)、荧光光谱(PL)等对巴里坤煤样所制备的CQDs进行进行结构和光学性能的表征。结果表明,制备的CQDs分散性良好,平均尺寸2.3 nm且具有良好的水溶性,在紫外区有很强的吸,可以发出黄色荧光。研究发现,基于微量金属离子对CQDs的猝灭作用,所制备的CQDs可应用于微量金属离子的探测。     

聚磷腈荧光纳米纤维用于选择性检测液相中苦味酸的研究

以六氯环三磷腈和4,4'-二羟基二苯砜为单体,通过一步沉淀聚合制备了环交联型聚磷腈荧光纳米纤维(PZS-NF),对其化学结构、形貌、热稳定性及荧光特性进行了表征;进一步以PZS-NF为荧光化学传感器,研究了其检测液相中苦味酸(PA)的性能,并探讨了检测机理.结果表明:PZS-NF的平均直径为80 nm,高度交联的有机-无机杂化结构赋予了其优异的热稳定性;纳米纤维在369 nm紫外光的激发下,在433 nm具有显著的荧光特性,对液相中的PA表现出了高灵敏、高效和高选择性的荧光猝灭响应;优异的检测性能缘于PZS-NF结构中具有大量富电子的氮原子,通过酸碱相互作用将PA分子富集到纳米纤维表面,从而有效促进了PZSNF与PA之间形成非荧光基态配合物,同时有利于PZS-NF向PA发生激发态能量转移.     

RAFT聚合制备结构明确的荧光标识聚甲基丙烯酸甲酯

以铁氰化钾为氧化剂,通过N-咔唑二硫代甲酸钠的水相氧化制备了高纯度的中间体二硫化双(N-咔唑硫代甲酰)(DTCD),DTCD以晶体的形式从水中析出,提纯简单,性质稳定.通过DTCD与偶氮二异丁腈(AIBN)或偶氮二氰基戊酸(ACVA)的反应合成了2种性能优异的叔丁腈酯基RAFT试剂,N-咔唑二硫代甲酸异丁腈酯(CYCBD)和N-咔唑二硫代甲酸氰基戊酸(CVCBD),新合成工艺的副反应和杂质被大量减少,最终产物的收率可达80%以上.以CYCBD和CVCBD为可逆加成断裂链转移(RAFT)试剂,研究了它们对甲基丙烯酸甲酯(MMA)RAFT聚合的控制能力,结果表明CYCBD和CVCBD是性能优异的RAFT试剂,可以很好地用于制备结构明确、分子量分布窄的链末端咔唑标记的聚甲基丙烯酸甲酯(CPMMA),由它们所制得的CPMMA的PDI小于1.2.研究结果还表明CYCBD和CVCBD及由其合成的CPMMA在四氢呋喃(THF)溶液中具有显著的荧光特性,CPMMA在358nm处有很强的荧光发射峰,而且,在浓度范围为0.1～20μmol/L的THF溶液中,CPMMA的荧光发射强度与其浓度具有良好的线性关系.通过CYCBD和CVCBD可以方便地制备结构明确且具荧光标识的功能聚合物。     

微波辐射无皂乳液聚合制备荧光乳液纳米粒子及其性能研究

以苯乙烯(St)为主要单体,对苯乙烯磺酸钠(NaSS)和可聚合稀土荧光配合物(Eu(AA)(BA)_2Phen)为功能性单体,通过微波辐射无皂乳液聚合制备了Poly(St-NaSS-Eu(AA)(BA)_2Phen)共聚物荧光乳液纳米粒子.利用红外光谱对共聚物的结构进行了证实;通过透射电子显微镜和扫描电子显微镜观察了粒子的形态、结构及大小;利用激光光散射粒度仪测试了粒子的大小及分布;结果发现所制备的共聚物荧光乳液纳米粒子呈大小均一的球形形状,粒径大小约为35 nm;采用荧光分光光度计测试,发现共聚物纳米粒子在595 nm和619 nm处出现Eu~(3+)的特征发射光谱,具有良好的荧光效果.     

自组装水热合成碳点-中空氧化硅纳米粒复合材料

利用反相微乳液体系制备出粒径均一的中空氧化硅纳米粒(SHN),以此为基础,再利用水热法通过自组装合成了碳点-中空氧化硅纳米粒复合材料(CD-SHN)。 采用高分辨透射电子显微镜(HRTEM)和场发射扫描电子显微镜(FESEM)对其结构进行了表征,结果显示SHN尺寸为30~40 nm,壳厚约为10 nm,在此基础上合成出具有和海葵类似结构的CD-SHN,尺寸约为1 μm,并且,在水相中具有良好的分散性。 海葵状CD-SHN既具有激发波长依赖的多色荧光发射性能,又具有良好的光稳定性,其最大激发及发射波长分别位于360和435 nm附近,经40 W白炽灯照射60 min,其荧光强度仍可保持97%。 该材料的制备过程条件温和,其原材料生物相容性良好,在生物造影方面具有潜在的优势。     

镉(Ⅱ)离子印迹聚合物的制备及性能研究

将量子点技术和离子印迹技术相结合,以镉(Ⅱ)为模板离子,CdSe/CdS量子点为荧光成分,甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,偶氮二异丁腈为引发剂,采用本体聚合法制备了镉(Ⅱ)离子印迹聚合物。利用X射线衍射仪(XRD)、扫描电镜(SEM)、傅里叶变换红外光谱仪(IR)、综合热分析仪(TG)等仪器对印迹聚合物进行表征,通过吸附实验和荧光猝灭实验考察其聚合物的吸附性能和荧光性能。结果表明:离子印迹聚合物内部存在大量的印迹空穴,并且具有良好的吸附性能和荧光性能。此聚合物有望作为固相萃取剂在分离富集领域获得应用。     

发光的异核稀土配合物装饰氧化石墨烯片

采用非共价键的方法制备一种新型的高荧光性能氧化石墨烯-异核稀土杂化材料。利用苯甲酸(BA)和菲咯啉(Phen)与Sm~(3+)和Gd~(3+)配位,并作用在氧化石墨烯片(GOSs)表面,制备了一种异核稀土配合物。所制备的产物通过傅里叶变换红外光谱、X射线衍射、扫描电子显微镜、荧光光谱仪、荧光寿命和热重分析来表征。该杂化材料具有强发光强度、长的寿命和良好的热稳定性。此外,Gd~(3+)对材料具有很强的敏化作用,同时Gd~(3+)在提高发光强度方面起着重要作用。氧化石墨烯的存在不会淬灭杂化材料的荧光性能。此外,还研究了具有不同物质的量之比的Sm~(3+)和Gd~(3+)的荧光特性。     

恒电位脉冲法制备聚苯胺薄膜及其表征

采用恒电位脉冲法制备聚苯胺薄膜, 利用扫描电子显微镜(SEM)、红外光谱(IR)、X射线衍射(XRD)及荧光光谱对所制备的薄膜进行比较与表征. 分别考察了循环周期、占空比及脉冲时间对薄膜形貌的影响. SEM形貌分析结果表明, 随着占空比的减小, 聚苯胺薄膜表面颗粒细化; 随循环周期的增加, 聚苯胺薄膜由片层结构转变为纵向生长的颗粒状结构. 荧光光谱分析结果表明, 聚苯胺薄膜具有光致发光性能, 发射峰位置约520 nm, 且发光强度随占空比的增大而增强. 电化学性能测试结果表明, 恒电位脉冲电位法制备的聚苯胺薄膜具有良好的电容特性.     

高热稳定性聚膦腈亚微米球的室温快速合成

以六氯环三膦腈（HCCP）和4,4′-二羟基二苯砜（BPS）为共缩聚单体,乙腈为溶剂,三乙胺为缚酸剂,在室温条件下,采用沉淀聚合的方法快速合成了一种聚膦腈亚微米球。 红外光谱、元素分析及X射线能谱分析(EDX)测试表明,该聚膦腈亚微米球具有高度交联的化学结构;扫描电子显微镜和透射电子显微镜测试表明,该聚膦腈亚微米球粒径分布在410 nm附近,而且具有光滑的表面和实心的结构;热重分析(TGA)测试表明,该聚膦腈亚微米球的热分解温度达到531 ℃。 并推测了该聚膦腈亚微米球的形成机理。     

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.