Templates, “Wheeled Reagents”, and a New Route to Rotaxanes by Anion Complexation: The Trapping Method

Abstract

The topological aspects of rotaxanes are compared with those of the other families of mechanically interlocked molecules: catenanes and molecular knots. The role of the different types of templates in the well-known threading and clipping procedures often used for rotaxane synthesis are discussed. Finally the conceptually new trapping method that is based on the action of supramolecular nucleophiles formed by anionic stopper-wheel complexes is described.

Efficient production of [ n ]rotaxanes by using template-directed clipping reactions

“…Recently, their potential applications as molecular switches for nanoelectronics (23,24) and molecular actuators for constructing artificial muscles (25), for fabricating smart surface materials (26), and for controlling the nanoscale release of molecules trapped in mesoporous silica (27)(28)(29) were demonstrated. Polyrotaxanes and well defined, homogeneous oligorotaxanes, in which the recognition sites on a dumbbell (an axle terminated by bulky stoppers) are encircled by large rings or macrocycles (wheels) by dint of molecular recognition, have become (30)(31)(32)(33)(34)(35)(36) one of the most intensively investigated subjects in mechanical chemistry. A general synthetic method for making rotaxanes, namely, the ''threading-followed-by-stoppering'' approach ( Fig.…”

Hydrogen-Bond-Mediated Template Synthesis of Rotaxanes, Catenanes, and Knotanes

“…The last section of this account is devoted to anion templates [235] for the synthesis of interlocked molecules [236]. Often, anion recognition [237][238][239][240][241][242] is more difficult to achieve with a controlled relative geometry of host and guest so that it may be more challenging to design a threaded host-guest complex based on anions.…”

Mass spectrometric evidence for catenanes and rotaxanes from negative-ESI FT-ICR tandem-MS-experiments

“…Another important difference is that axles 19 and 20 do not have any groups that are prone to forming strong hydrogen bonds with any of the macrocycles, while the phenolate formed upon deprotonation of 21 is capable of strong hydrogen bonding to two amide groups of the macrocycles. In dichloromethane, a binding constant of K > 10 5 M −1 was determined The strong binding of phenolates and other anions to tetralactam macrocycles in solution has been utilized for designing template effects for efficient rotaxane synthesis [20][21][22][28][29][30][31][32][33]. In the gas phase, one might expect the binding to be even stronger because there is no competition with the solvent anymore.…”