Synthesis of Calix[4]pyrroles: A Class of New Molecular Receptor

RecentlySesslerandco-workersdiscoveredthatthemeso-octaalkylporphyrinogensshowedinterestinganionandneutralsubstratebindingpropertiesandmightserveasaclassofneweasy-to-makemolecularreceptorintheareaofsupramolecularchemistry'.However,themeso-octaalkylpor...     

二氰基二硫纶·二甲基联吡啶镉(Ⅱ)配合物的合成与谱学特性的研究

以氰化钠、二硫化碳、二甲基联吡啶及氯化镉为起始原料,合成了一种功能性新型二氰基二硫纶·二甲基联吡啶合镉（ Ⅱ） 配合物Ｃｄ（ｍｎｔ）（ｄｍｂｐ）（ｍｎｔ＝ １,２＿ｄｉｃｙａｎｏ＿１ ,２＿ｅｔｈｙｌｅｎｅｄｉｔｈｉｏｌａｔｅ,ｄｍｂｐ＝ ４ ,４′＿ｄｉｍｅｔｈｙｌ＿２ ,２′＿ｂｉｐｙｒｉｄｉｎｅ） 。经元素分析、热谱、摩尔电导、红外光谱、电子吸收光谱和发射光谱表征,其结构为四配位的电中性配合物。热分解温度高于３０５ ℃。在ＤＭＦ、ＤＭＳＯ中溶解度较好;在ＴＨＦ、Ｐｙ、丙酮中次之;在氯仿、乙醇、甲醇中溶解度较差,几乎不溶于水、乙醚、苯中     

傅里哀变换红外发射光谱法研究金属氧化物催化剂——Ⅰ.实验建立及氧化钼的还原-氧化研究

本文报导了傅里哀变换红外发射光谱法研究多相氧化物催化剂的实验装置的建立及实验条件的考察。设计加工了一个温度范围宽,可在各种气氛和真空条件下原位研究氧化物催化剂的红外发射池。以MoO_3为例,考察了样品厚度,测试温度对发射光谱的影响。当样品量小于1mm·cm~(-2)时,随样品量增加,谱峰强度线性增加,但峰形不发生变化。当样品量高于1mg.cm~(-2)时,随样品量增加,谱图严重畸变。随样品温度升高,谱峰强度近似线性增加。并用该方法研究了MoO_3在还原和再氧化过程中表面氧物种的变化。结果表明桥式MO?O?Mo物种比端基Mo=O物种较易还原,再氧化时,Mo=O物种比Mo?O?Mo物种优先形成。     

Hydrogenation of CO over carbides of tungsten

CO hydrogenation on tungsten carbides has been investigated.The methanation activitiesof tungsten carbides are comparable to that of supported Group VIII metal catalysts.Temperature-programmed thermal desorption spectra of CO on tungsten carbide show that CO is adsorbed non-dissociatively,and the surface—CO bond appears to be rather weak.     

Photoswitchable Sol–Gel Transitions and Catalysis Mediated by Polymer Networks with Coumarin-Decorated Cu24L24 Metal–Organic Cages as Junctions

Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre-irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu₂₄L₂₄ metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between Cu^II, Cu^I, and Cu⁰. The instability of the MOC junctions in the Cu^I and Cu⁰ states leads to network disassembly, forming Cu^I/Cu⁰ solutions, respectively, that are stable until re-oxidation to Cu^II and supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper-catalyzed azide-alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks.