Tin (IV) chloride-promoted one-pot synthesis of novel tacrine analogues

A facile synthesis of potential acetylcholinesterase (AChE) inhibitors, the tacrine analogues 3a-p, has been accomplished by direct cyclocondensation of 1-aryl-4-cyano-5-aminopyrazole with β-ketoesters using tin(IV) chloride as catalyst. The structures of all the compounds have been confirmed by IR, 1H- and 13C-NMR.     

Influence of halogen substituents on the catalytic oxidation of 2,4,6-halogenated phenols by Fe(III)-tetrakis(p-hydroxyphenyl) porphyrins and potassium monopersulfate

The influence of halogen substituents on the catalytic oxidation of 2,4,6-trihalogenated phenols (TrXPs) by iron(III)-porphyrin/KHSO? catalytic systems was investigated. Iron(III)-5,10,15,20-tetrakis(p-hydroxyphenyl)porphyrin (FeTHP) and its supported variants were employed, where the supported catalysts were synthesized by introducing FeTHP into hydroquinone-derived humic acids via formaldehyde poly-condensation. F (TrFP), Cl (TrCP), Br (TrBP) and I (TrIP) were examined as halogen substituents for TrXPs. Although the supported catalysts significantly enhanced the degradation and dehalogenation of TrFP and TrCP, the oxidation of TrBP and TrIP was not enhanced, compared to the FeTHP catalytic system. These results indicate that the degree of oxidation of TrXPs is strongly dependent on the types of halogen substituent. The order of dehalogenation levels for halogen substituents in TrXPs was F > Cl > Br > I, consistent with their order of electronegativity. The electronegativity of a halogen substituent affects the nucleophilicity of the carbon to which it is attached. The levels of oxidation products in the reaction mixtures were analyzed by GC/MS after extraction with n-hexane. The most abundant dimer product from TrFP via 2,6-difluoroquinone is consistent with a scenario where TrXP, with a more electronegative halogen substituent, is readily oxidized, while less electronegative halogen substituents are oxidized less readily by iron(III)-porphyrin/KHSO? catalytic systems.     

Bifurcations of Double Homoclinic Loops with Inclination Flip and Nonresonant Eigenvalues

In this work, bifurcation analysis near double homoclinic loops with Ws inclination ?ip of Γ1 and nonresonant eigenvalues is presented in a four-dimensional system. We establish a Poincar´e map by constructing local active coordinates approach in some tubular neighborhood of unperturbed double homoclinic loops. Through studying the bifurcation equations, we obtain the condition that the original double homoclinic loops are persistent, and get the existence or the nonexistence regions of the large 1-homoclinic orbit and the large 1-periodic orbit. At last, an analytical example is given to illustrate our main results.     

集值优化问题超有效解的高阶Mond-Weir对偶

在实赋范线性空间中利用锥方向高阶广义邻接导数研究带约束的集值优化在超有效解意义下的高阶Mond-Weir对偶问题.在广义锥-凸假设下,利用锥方向高阶广义邻接导数的性质借助凸集分离定理得到了强对偶定理.利用超有效点的标量化定理得到逆对偶定理.     

A Novel Pyrene Fluorescent Sensor Based on the π–π Interaction Between Pyrene and Graphene of Graphene–Cadmium Telluride Quantum Dot Nanocomposites

In this article, water-soluble graphene–cadmium telluride quantum dot nanocomposites were fabricated through the synthesis of cadmium telluride quantum dots in the presence of graphene aqueous dispersion. It was found that pyrene could remarkably quench fluorescence of graphene–cadmium telluride quantum dot nanocomposites. On this basis, a novel method for the determination of pyrene was developed. Factors affecting the pyrene detection were investigated, and the optimum conditions were determined. Under the optimum conditions, a linear relationship could be established between the quenching of fluorescence intensity of graphene–cadmium telluride quantum dot nanocomposites and the pyrene concentration in the range of 6.00 × 10^?8–2.00 × 10^?6 mol L^?1 with a correlation coefficient of 0.9959. The detection limit was 4.02 × 10^?8 mol L^?1. Furthermore, the nanocomposites were applied to practical determination of pyrene in different water samples with satisfactory results.     

Structural controlled pure metallo-triangular assembly through bisterpyridinyl Dibenzo[b,d]thiophene,Dibenzo[b,d]furan and Dibenzo[b,d]carbazole

A novel family of metallocycles was constructed by a one-pot self-assembly of three analogous bis(terpyridine) ligand monomers L1-L3, having different bent angles, with metal ions (Zn²⁺ or Cd²⁺). The dibenzo[b,d]thiophene-containing ligand L3 assembled with the metal ions to form a single trimer, whereas the dibenzo[b,d]furan-containing ligand L2 and dibenzo[b,d]carbazole-containing ligand L1 formed a mixture of trimers and tetramers. Heteroatoms (N, O, S) significantly contributed to the molecular size of the assemblies, owing to the bent angle of the bis-terpyridines ligands.     

Porphyrin Nanocage‐Embedded Single‐Molecular Nanoparticles for Cancer Nanotheranostics

Single molecular nanoparticles (SMNPs) integrating imaging and therapeutic capabilities exhibit unparalleled advantages in cancer theranostics, ranging from excellent biocompatibility, high stability, prolonged blood lifetime to abundant tumor accumulation. Herein, we synthesize a sophisticated porphyrin nanocage that is further functionalized with twelve polyethylene glycol arms to prepare SMNPs ( porSMNPs ). The porphyrin nanocage embedded in porSMNPs can be utilized as a theranostic platform. PET imaging allows dynamic observation of the bio‐distribution of porSMNPs , confirming their excellent circulation time and preferential accumulation at the tumor site, which is attributed to the enhanced permeability and retention effect. Moreover, the cage structure significantly promotes the photosensitizing effect of porSMNs by inhibiting the π–π stacking interactions of the photosensitizers, ablating of the tumors without relapse by taking advantage of photodynamic therapy.     

Covalent bonding photosensitizer–catalyst dyads of ruthenium-based complexes designed for enhanced visible-light-driven water oxidation performance

Transition Metal Chemistry - We have successfully prepared two ruthenium-based covalent bonding photosensitizer–catalyst dyads through a simple procedure. 1H NMR spectra of both dyads show...     

贵金属多孔纳米结构的模板法制备及生物检测应用

贵金属多孔纳米材料是一类非常重要的新型多功能纳米材料,其具有独特的空心内部、多孔的外壁以及可调的形貌等,表现出优异的光、电、催化等特性。调制贵金属多孔纳米材料的尺寸、形状、排列和空间取向等对促进其在拉曼光谱、生物传感等方面的应用至关重要。模板法是利用与目标产物的纳米尺度特征相匹配的预制结构来指导纳米材料的合成,可以制备出其他方法难以制备的新型多孔纳米结构材料。基于模板的多样性,能够便捷的调节多孔贵金属的孔径、尺寸和组分,充分的开发贵金属纳米结构的特性。本文着重介绍了贵金属多孔纳米材料的类型和调控这些纳米结构的各种模板方法,分析了各种制备方法的优势和不足,并简要综述了贵金属多孔纳米结构在生物检测方面的一些应用进展。     

Similar or different: the same Spiro-core but different alkyl chains with apparently improved device performance of perovskite solar cells

By intelligently utilizing the odd-even effect existing in the melting points of alkanes as presented in the basic textbook of Organic Chemistry, different alkoxy groups were introduced to modify the structure of commercial Spiro-OMeTAD to give new Spiro derivatives of Spiro-OEtTAD, Spiro-OPrTAD, Spiro-OiPrTAD and Spiro-OBuTAD, with the aim to adjust the molecular packing status in perovskite solar cells as hole transporting compounds. Excitedly, with the introduction of ethoxy groups instead of the methoxy ones in Spiro-OMeTAD, Spiro-OEtTAD-based perovskite solar cells demonstrated the highest device performance of 20.16%, higher than that of Spiro-OMeTAD(18.64%).