Issue 34, 2021

Further investigations of the crystal-to-crystal phase transition of a [2]pseudorotaxane composed of ferrocene-terminated dialkylammonium and dibenzo[24]crown-8-ether

Abstract

[2]Pseudorotaxane, [(FcCH2NH2CH2C6H4-4-Me)(DB24C8)][PF6] ([1][PF6]; Fc = ferrocenyl and DB24C8 = dibenzo[24]crown-8-ether), undergoes crystalline phase transition at 128 °C upon heating and at 106 °C upon cooling (α-phase at low temperature; β-phase at high temperature), as shown in our previous reports. This paper presents new results from the detailed studies on the crystal phase transition of pseudorotaxane, the dielectric constant of the crystal, and the formation of a gel from a PhCl solution. The crystalline phase transition has been revealed to accompany the partial rotation of the DB24C8 molecule while maintaining the hydrogen bonds between the axle and macrocyclic component molecules. The ultrasonication of a PhCl suspension of a mixture of the axle and cyclic molecules forms a gel, which is composed of microcrystalline [1][PF6] with a new crystal form (α′-phase). The pseudorotaxane crystals with mixed counter anions, [1][PF6]1−x[Y]x (Y = AsF6 and SbF6), exist in the α- or β-phase, depending on the anion composition. Further, [1][PF6]0.28[AsF6]0.72 and [1][PF6]0.76[SbF6]0.24 are obtained in the α-phase, while [1][PF6]0.65[SbF6]0.35 crystallises in the β-phase. The phase transition temperature of the pseudorotaxane with PF6 and SbF6 counter anions is investigated using differential scanning calorimetry (DSC).

Graphical abstract: Further investigations of the crystal-to-crystal phase transition of a [2]pseudorotaxane composed of ferrocene-terminated dialkylammonium and dibenzo[24]crown-8-ether

Supplementary files

Article information

Article type
Paper
Submitted
06 abr 2021
Accepted
20 jun 2021
First published
06 jul 2021

CrystEngComm, 2021,23, 5944-5952

Further investigations of the crystal-to-crystal phase transition of a [2]pseudorotaxane composed of ferrocene-terminated dialkylammonium and dibenzo[24]crown-8-ether

Y. Suzaki, Y. Fukuchi, H. Tadami, T. Koizumi, K. Osakada, T. Ide, M. Horie, N. Hoshino and T. Akutagawa, CrystEngComm, 2021, 23, 5944 DOI: 10.1039/D1CE00457C

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