Supramolecular Chemistry with Macromolecules:  New Self-Assembly based Main Chain Polypseudorotaxanes and Their Properties

Abstract

A new class of main chain polypseudorotaxanes, 8, was prepared by self-assembly of a poly(ester crown ether), poly[bis(5-methylene-1,3-phenylene)-32-crown-10 sebacate] (5), and N,N‘-bis(β-hydroxyethyl)-4,4‘-bipyridinium bis(hexafluorophosphate) (6). The equilibrium constant (K = 58.0 M-1 at 21.8 °C), ΔH (−26.5 kJ/mol) and ΔS (−56.4 J/mol deg)(all averages from several iterative methods) for the formation of 8 were measured by proton NMR spectroscopy. Compared to those (K = 247 M-1 at 21.8 °C, ΔH = −44.7 kJ/mol, ΔS = −106 J/mol deg) for the model system, bis(5-acetoxymethyl-m-phenylene)-32-crown-10 (4) and 6, the enthalpy term is less favorable for the polymeric system, while the entropy term is less unfavorable. The measured values enabled us to design polypseudorotaxanes with targeted degrees of threading (m/n, the fraction of the cyclic moieties threaded with linear species). The solubility of polypseudorotaxane 8 was different from both starting materials 5 and 6, and depended on the m/n value. Polypseudorotaxanes 8 with higher m/n had higher viscosities because of increased hydrodynamic volume in solution and were more rigid as manifested by higher glass transition temperatures (T g) in the solid state. Dethreading (decomplexation) took place above T g in the solid state, causing loss of color (orange), a process potentially useful for temperature sensors.

A responsive supramolecular metallogel constructed by coordination-driven self-assembly of a crown ether-based [3]pseudorotaxane and a diplatinum(ii) acceptor

“…3, the electron microscopy images of the xerogel show a nanoribbon morphology which can account for the orthogonal noncovalent interactions to form entangled networks (Fig. 18 Therefore, heating and cooling can result in a reversible gel-sol transition in this obtained supramolecular metallogel (Fig. These results showed that the metal-coordination interactions between the [3]pseudorotaxane and 3 not only achieved the conversion from low-molecular-weight aggregates to the 3D supramolecular polymeric network, but also made an impact on the microscopic nature of the resulting supramolecular metallogel.…”

New polymer architectures: Recent results with polyrotaxanes

“…34), reduces the losses from dethreading during the polymerization (Ref. 35), i.e., llK=finite, accounting for the lower degrees of dethreading observed for the polyurethane systems of Type A relative to the analogous polyesters (Scheme 3). Another exciting finding is that it is possible to contol the locus of the crown ether rings in these polyrotaxanes by use of solvent; in CDC1, hydrogen bonding localizes the rings on the urethane moieties, whereas in DMSO the crown ethers are delocalized over other portions of the backbone.…”

[2]pseudorotaxanes derived from 27‐ and 29‐membered oxaazacyclophanes and 1,2‐bis(benzimidazolium)ethane salts

“…Within this context, benzylammonium, benzimidazolium, and pyridinium cations have been widely used as axles to construct pseudorotaxanes and rotaxanes . Among the most frequently employed wheels are crown ethers, cyclodextrins, cucurbituril, calixarenes, and cyclophanes …”

“…Within this context, benzylammonium, benzimidazolium, and pyridinium cations have been widely used as axles to construct pseudorotaxanes and rotaxanes. [15][16][17][18][19][20][21][22][23][24][25][26] Among the most frequently employed wheels are crown ethers, [27][28][29] cyclodextrins, [30,31] cucurbituril, [32][33][34] calixarenes, and cyclophanes. [35][36][37][38] Herein, we report on a novel series of 27-and 29-membered oxaazacyclophanes, which were prepared from aromatic dialdehyde and diamine building blocks and then structurally characterized.…”