Rotaxane Synthesis Analysis

3. Experiment Plan:

The experiment section of the whole project will be divided into two phases, namely Phase I (organic synthesis phase) and Phase II (detection phase).

3.1 Organic synthesis phase

For Phase I, an anthracene containing dynamic [2] rotaxane will be synthesized by the active template method.19 The whole rotaxane architecture will be divided into three parts during the synthesis process, two of them will make up the macrocycle of the rotaxane while the other one is the dumbbell thread.

3.1.1 Synthesis of first part of the macrocycle

First of all, tetraethylene glycol (TEG) is reacted with 4-tosyl chloride (TsCl), using triethylamine as the reagent and 4-dimethylaminopyridine as a base catalyst and dichloromethane as solvent.

The reaction mixture is heated at 1010C for 5 hours.19 The figure below shows the corresponding pathway for the synthesis of the dialdehyde. Figure 15 Synthesis of the second part of the macrocycle

3.1.4 Self-assembly of the rotaxane

Since the rotaxane has the property of self-assembly, by mixing the three components above in acetonitrile (ACN) for several hours will form the targeted [2] rotaxane.19 Figure 16 Self-assembly process of the rotaxane

Adopted from: Wong, W. et al. Organic & Biomolecular Chemistry 2010, 8

3.2 Detection phase

As for Phase II (detection phase), several metal ions will be selected to form complex with the macrocycle and the anthracene fluorescence will be detected.

3.2.1 Preparation of samples

For the preparation of samples, two stock solutions, the metal ion and the rotaxane solution will be prepared separately. The solution will be mixed together to form a sample solution, which will be tested for the fluorescence intensity. A blank solution of the rotaxane will also be prepared. Figure below shows a schematic illustration of the preparation of the

After that, 200 mole equivalent of water will be added to dissociate the rotaxane sensor.11，19 Literature suggested that 200 mole equivalent of water causes the most steady dissociation of the rotaxane.19 Figure shows the plot of rotaxnae concentration when different mole equivalents of water is added. Figure 18 Plot of rotaxane concentration upon different mole equivalent of water