Macrobicyclic aminals

The synthesis of Schiff base macrocycles in the absence of templating cations and in non-protic and non-coordinating solvent media is reported. The reaction of pyridine-2,6-dicarboxaldehyde with the diamines 1,2-bis(2-aminophenoxy) ethane and 1,4-bis(2-aminophenoxy) butane has been found to give the corresponding macrobicyclic aminals. The chemical properties of the aminals are reported together with a preliminary study of their metal complexation reactions. The X-ray crystal structure of the aminal derived from pyridine-2,6-dicarboxaldehyde and 1,2-bis(2-aminophenoxy) ethane has been determined and verifies the macrobicyclic nature of the product.This paper is dedicated to the memory of the late Dr C. J. Pedersen.     

蛋白质链环和纽结

寻找和合成拓扑新颖结构的蛋白质是目前一个崭新的课题 ,本文介绍了已经发现的M bius蛋白质和蛋白质链环的新奇结构及实验事实     

Cellular Synthesis of Protein Catenanes

Direct cellular production of topologically complex proteins is of great interest both in supramolecular chemistry and protein engineering. We describe the first cellular synthesis of protein catenanes through the use of the p53 dimerization domain to guide the intertwining of two protein chains and SpyTag–SpyCatcher chemistry for efficient cyclization. The catenane topology was unambiguously proven by SDS‐PAGE, SEC, and partial digestion experiments and was shown to confer enhanced stability toward trypsin digestion relative to monomeric control mutants. The assembly–reaction synergy enabled by protein folding and genetically encoded protein chemistry offers a convenient yet powerful approach for creating mechanically interlocked, complex protein topologies in vivo.     

Analysis of Multiring Aromatic Hydrocarbons by HPLC Using a Reverse-Phase Radial Compression Column Systemt

Abstract

The performance of a radially-compressed C₁₈ reverse-phase column system for analysis of multiring aromatics has been assessed in terms of efficiency, resolution and analysis time, and these parameters are compared with those reported for other column systems. The optimum conditions for analysis were established using nine standard aromatic compounds. These conditions are aslo shown to be suitable for analysis of complex mixtures of aromatic compounds obtained from petroleum refinery effluent waters, marine biota and combustion residues (soot).     

De Novo Construction of Catenanes with Dissymmetric Cages by Space-Discriminative Post-Assembly Modification

Considerable efforts have been made to increase the topological complexity of mechanically interlocked molecules over the years. Three-dimensional catenated structures composed of two or several (usually symmetrical) cages are one representative example. However, owing to the lack of an efficient universal synthetic strategy, interlocked structures made up of dissymmetric cages are relatively rare. Since the space volume of the inner cavity of an interlocked structure is smaller than that outside it, we developed a novel synthetic approach with the voluminous reductant NaBH(OAc)₃ that discriminates this space difference, and therefore selectively reduces the outer surface of a catenated dimer composed of two symmetric cages, thus yielding the corresponding catenane with dissymmetric cages. Insight into the template effect that facilitates the catenation of cages was provided by computational and experimental techniques.     

Potassium Cryptate of a Macrobicyclic Ligand Featuring a Reducible hexakis(phenylthio)benzene electron-acceptor site

The synthesis and structural characterization of the macrobicyclic ligand 1 containing a reducible hexakis-(phenylthio)benzene electron-acceptor site is described. It is based on the condensation of the tetraoxa-diazamacrocycle 3 with a suitably functionalized derivative 4 of hexakis(phenylthio)benzene. Complexation of a potassium cation by 1 gives the corresponding cryptate 2 , with a stability constant of ca. 4000 M ^?1 as determined by ¹H-NMR titration in CD₃CN. The reduction potential of the hexakis(phenylthio)benzene electron-acceptor site in 2 is shifted by 170 mV towards more positive values with respect to that in 1 by complexation of potassium.     

Catenanes: Fifty Years of Molecular Links

Half a century after Schill and Lüttringhaus carried out the first directed synthesis of a [2]catenane, a plethora of strategies now exist for the construction of molecular Hopf links (singly interlocked rings), the simplest type of catenane. The precision and effectiveness with which suitable templates and/or noncovalent interactions can arrange building blocks has also enabled the synthesis of intricate and often beautiful higher order interlocked systems, including Solomon links, Borromean rings, and a Star of David catenane. This Review outlines the diverse strategies that exist for synthesizing catenanes in the 21st century and examines their emerging applications and the challenges that still exist for the synthesis of more complex topologies.     

Macrobicyclic hexalactones — Synthesis,host-guest properties and electrochemistry

The synthesis of a family of new host type molecules (1–4) bearing six lactone structural units is described. One of the lactones (1) forms crystals which contain benzene in a 12 (host:guest) ratio. The complexation behaviour towards potential guest molecules and the electrochemical properties of the molecules are studied. Compared to an analogous open chained ester (18) the electrochemical potentials of the bicyclic lactones,1, 2 are higher due to the different steric environment.     

Synthesis of Macrobicyclic Polyamines by Direct Macrobicyclisation via Tripode-Tripode Coupling

The synthesis of five macrobicyclic polyamines 1 – 5 is described following a route in which the macrobicycle is formed by the coupling of two tripodal subunits. Such a sequence is appreciably shorter than the stepwise construction via a macrocycle, and may give higher yields, as illustrated by the case of bis-tren 3 , which has been synthesized following both routes.