Bridging host-guest chemistry with molecule chemistry-covalent organic polyrotaxanes (COPRs): from synthesis to inactivation of bacterial pathogens

Abstract

As a thriving artificial material, covalent organic frameworks (COFs), boasting inherent structural designability and functional adaptability, and with compositions akin to biological macromolecules, have emerged as a rising star in the field of material science. However, the progression of COFs is significantly impeded by the arduous and intricate preparation procedures of novel building blocks, as well as the inefficient development process of new reactions. An efficient, uncomplicated, and versatile functionalization approach, which has the potential to not only facilitate customized preparation of COFs based on application demands but also enable precise performance control, has become a focal point of research. The formulation of multi-functional COFs through efficient and cost-effective methods poses a critical challenge for the practical application of COFs. This review aims to present the preparation of COFs by amalgamating rigid molecular chemistry with flexible supramolecular host-guest chemistry, adopting a "couple hardness with softness" strategy to meticulously construct intelligent covalent organic polyrotaxanes (COPRs) using conventional reactions. Herein, novel building blocks can be acquired by amalgamating existing macrocycle complexes with framework blocks. The amalgamation of supramolecular chemistry bolsters the capabilities to generate, sense, respond, and amplify distinctive signals, thereby expediting the advancement of multifaceted materials with sophisticated structures. Concurrently, the infusion of supramolecular force endows COPRs with exceptional performance, facilitating multi-mode collaborative antibacterial therapy. This comprehensive review not only promotes the efficient utilization of resources but also stimulates the rapid advancement of framework materials.

Fig. 1. Typical macrocycles with different spatial topological structure for the preparation of host–guest complex.

Fig. 2. Possible host–guest complex for the construction of COPRs (a) host–guest complex (1 : 1); (b) host–guest complex (1 : 2 and 2 : 2).

Fig. 3. Typical COPRs based on the Schiff-base chemistry.

Fig. 4. Typical COPRs based on the Michael addition–elimination reaction.

Fig. 5. Typical structure of cyclodextrin (CD) host, aromatic guest, as well as corresponding host–guest complex.

Fig. 6. Schematic representation of the synthesis and antimicrobial application of Por-CD-COF. (a) The typical route for the synthesis of Por-CD-COF and the typical structure of Por-CD-COF; (b) schematic antimicrobial mechanism for the Por-CD-COF.

Fig. 7. Schematic diagram of the synthesis and antimicrobial mechanism of Crown-COPR-Zn. PTT, PDT and ROS refer to photothermal therapy, photodynamic therapy, and reactive oxygen species, respectively.

Fig. 8. (a) Schematic route for the preparation of COPRs via the Michael addition–elimination reaction; (b) representative structure of COPRs obtained from the Michael addition–elimination reaction: (c) schematic route for the preparation of COPRs via the Schiff base reaction.

Fig. 9. Schematic route for the preparation of crown-ether and cucurbit[7] ring mechanically intercalated COPRs: (a) Crown-COF, and zinc(ii) ion coordinated Crown-COF-Zn; (b) TpVCB[7].