Efficient and selective transport of ω-amino acids across a bulk chloroform membrane by a macrocyclic dicopper(II) complex
摘要:
The Cu(II) complex of a ditopic macrocyclic ligand efficiently transports omega-amino acids of different length across a bulk chloroform membrane with promising selectivity. (C) 2004 Elsevier Ltd. All rights reserved.
also characterised the related [Mn(nta)]− complex (nta = nitrilotriacetate). Both the [Mn(paada)]− and [Mn(nta)]− complexes turned out to contain two inner-sphere water molecules in aqueoussolution. The exchange rate of these coordinated water molecules was slower in [Mn(paada)]− (k298ex = 90 × 107 s−1) than in [Mn(nta)]− (k298ex = 280 × 107 s−1). The complexes were also characterised using both DFT
我们报告了一个五齿配体,其中包含一个在氮原子上被吡啶甲酸基团官能化的2,2'-氮杂二烯基二烯二酸部分(H 3 paada),以及在吡啶基环的第4个位置被十二烷氧基官能化的脂族衍生物3 C 12 Opaada)。使用电位滴定法和分光光度滴定法(25°C,0.15 M NaCl)的组合测定了paada 3-配体的质子化常数和Mn(II)络合物的稳定性。通过记录1 H核磁弛豫色散(NMRD)曲线和17O化学位移和弛豫率。这些研究提供了关于微观参数的详细信息,这些微观参数控制了它们在体外作为松弛剂的效率。为了完整性和便于比较,我们还对相关的[Mn(nta)] -配合物(nta =次氮基三乙酸酯)进行了表征。结果表明,[Mn(paada)] -和[Mn(nta)] -配合物在水溶液中均包含两个内层水分子。这些配位水分子的交换速率在[Mn(paada)] -(k 298 ex = 90×10 7 s -1)中比在[Mn(nta)]
Mechanochemistry with Metallosupramolecular Polymers
作者:Diederik W. R. Balkenende、Souleymane Coulibaly、Sandor Balog、Yoan C. Simon、Gina L. Fiore、Christoph Weder
DOI:10.1021/ja5051633
日期:2014.7.23
The transduction of mechanical force into useful chemical reactions is an emerging design approach to impart soft materials with new functions. Here, we report that mechanochemical transductions can be achieved in metallosupramolecular polymers. We show that both reversible and irreversible reactions are possible and useful to create mechanically studied was a cross-linked network assembled from a europium salt and a responsive materials that display new functions. The metallopolymer telechelic poly(ethylene-co-butylene) with 2,6-bis(1'-methyl-benzimidazolyl)pyridine (Mebip) ligands at the termini. The Eu3+ complexes serve both as mechanically responsive binding motifs and as built-in optical probes that can monitor the extent of (dis)assembly due to their characteristic photoluminescent properties. Indeed, dose-dependent and reversible metal ligand dissociation occurs upon exposure to ultrasound in solution. The absence of ultrasound-induced dissociation of a low-molecular weight model complex and in-depth studies of temperature effects confirm that the dissociation is indeed the result of mechanical activation. The influence of the strength of the metal-ligand interactions on the mechanically induced dissociation was also explored. Metallopolymers in which the Mebip ligands were substituted with more strongly coordinating dipicolinate (dpa) ligands do not dissociate upon exposure to ultrasound. Finally, we show that mechanochemical transduction in metallosupramolecular polymers is also possible in the solid state. We demonstrate mending of damaged objects through ultrasound as well as mechanochromic behavior based on metal-exchange reactions in metallopolymers imbibed with an auxiliary metal salt.