| Supramolecular chemistry is a branch of chemistry sciences, which focuses on the complicated but ordered systems assembled by two or more molecular through various non-covalent bonds. Host-guest interaction is an important part of supramolecular chemistry. Through host-guest recognition, various molecules with special topological structures and functions, such as pseudorotaxane, rotaxane and catenane, have been fabricated. Besides these, supramolecular polymers are also constructed, which have similar topological structures with covalent polymers, such as linear polymer, star polymer, branched polymer, hyperbranched polymer and polymer network. Now, supramolecular polymers are being a hot topic of research.These two-dimensional and three-dimensional supramolecular polymers, constructed by host-guest recognition, have important significance not only in topological structures but in properties and functions. For supramolecular polymers are fabricated by binding monomeric units via reversible non-covalent interactions, they usually respond to a diverse range of external stimuli, such as p H values, temperatures, and ions. Such responsiveness endows supramolecular polymers with superb self-healing and degradability. This type of polymers is being developed for potential applications in the fields of smart materials, molecular devices, healable and degradable materials.In the past decade, many studies focus on new recognition systems, assembly mechanism and topological structures. In contrast, little effort has been made to investigate their properties and controllable transformations. The transition from novel topological structures to novel properties and functions is going on the way.The topological structure of polymers is an important parameter, which greatly influenced the properties of polymers. As we all know, supramolecular polymers are constructed by host-guest recognition, and have responsiveness to external stimuli, which makes the topological structures change easily. We therefore ask whether such topological transition can lead to the change of polymeric properties.As reported, the conjugation molecules with AB2 type formed supramolcular hyperbranched polymers upon host-guest interaction. During this process, the π-π stacking interaction of the molecules was changed. As a result, the photophysical properties are changed reversibly. Besides these, the flexible supramolecular hyperbranched polymers and polymer networks formed supramolecular gels at high concentration, which would transit into a sol state for the depolymerization of the polymers. We therefore ask whether such depolymerization can lead to the change of photophysical properties. And then, we synthesized a series of rigid conjugated polymers with DB24C8 side chains, which formed supramolcular polymer networks upon addition of C12-2H·X(X=PF6, Cl). The main research contents and results were generalized as follows:1, A light-emitting supramolecular polymer(MP-Zn) was fabricated by complexing Zn(II) with a conjugated bis-terpyridine ligand bearing two DB24C8 groups. Upon addition of C12-2H·PF6, the supramolcular polymer network was formed and the fluorescence decreased. Subsequent addition of base led to the disassembly of polymer network and the recovery of fluorescence.2, A series of TPE-containing polymers with different structures were synthesized. The polymers inherited the AIE feature of TPE. Upon addition of C12-2H·X, the supramolcular polymer networks were formed and the fluorescence increased. Subsequent addition of base led to the disassembly of polymer networks and the recovery of fluorescence.3, The reduplicative complexation of AP-TPE and C12-2H·Cl not only enhances the fluorescence remarkably, but also induces a morphological transformation from micellar to vesicular.We hope that such supramolcular systems with acid-base responsiveness and reversible fluorescence can be used in fields of OLED, molecular devices and sensors. |
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