Abstract
A series of new [2]pseudorotaxanes “[2FcDB24C8](PF6) and [2FcDB24C8](PF6) (X = Br or I)”, composed of dibenzo[24]crown-8 ether (DB24C8) or tetrahalide substituted DB24C8 (DB24C8-X4) as a ring molecule have been synthesized. Being more comprehensible, these pseudorotaxanes are named 1, 2 and 3. The synthesis of biferrocene-containing axle molecule was carried out by the following steps. Ferroceneboronic acid served as a starting material. This was converted to iodoferrocene by addition of N-iodosuccinimide followed by Ullmann coupling to produce biferrocene. In between, different reaction conditions were attempted. Hence, optimization of reaction is reported in Chapter 2.3. The resulting products were identified by 1H NMR spectroscopy (500 MHz, CDCl3, r.t.) in every step. In the analysis section, we examined the response of the new [2FcDB24C8](PF6) crystals to laser irradiation at 445 nm, which intensity was comparable to the previously reported crystals of mono-ferrocene-containing [2]pseudorotaxane, [FcDB24C8](PF6) or pseudorotaxane 4. We have foreseen a rapid and reversible deformation of the crystals, as observed under optical microscope. From the X-ray single crystallography, we then studied the molecular interaction within the crystal and justified that it was due to the intra- and the intermolecular - interactions. Optical anisotropy, in particular thermal phase transition of the single crystals of the pseudorotaxane, was analyzed by polarizing optical microscopy (POM) with a Berek compensator. Furthermore, phase transition of the three types of crystals in respond to thermal stimuli was observed from POM images, differential scanning calorimetry (DSC), and X-ray crystallography.