Chalcogenoviologen Enhanced Host–Guest Recognition

In the field of supramolecular chemistry,cyclophanes with novel properties are highly sought after since they can be tailored to fulfill specific tasks.In this article,we incorporate chalcogenoviologen-based units into tetracationic cyclophanes,resulting in enhanced host–guest recognition.The cyclophanes can be tuned through the addition of chalcogen bridging atoms—S,Se,and Te—which enhance their rigidity,regulate bond rotation and introduce additional steric bulk.Three cyclophanes containing chalcogen bridging atoms were synthesized and characterized in both the solution and solid states.The energy barriers for their interconversion between syn-and anti-conformations in solution were found to be correlated with chalcogen atom size.The photophysical properties of the cyclophanes are strongly dependent on the chalcogen atomic number,with intersystem crossing rates increasing from S to Se to Te.UV–vis-NIR spectroscopic and fluorometric titrations revealed that the chalcogenoviologenbased cyclophanes exhibit significantly stronger binding with electron-rich guests compared to the well-known,unsubstituted cyclobis(paraquat-pphenylene).This enhancement in binding can be attributed to restricted rotation within the chalcogenoviologen units.This research provides insight into the rational design and tailored synthesis of cationic cyclophanes.

All-hydrocarbon,all-conjugated cycloparaphenylene-polycyclic aromatic hydrocarbon host–guest complexes stabilized by CH–πinteractions

Polycyclic aromatic hydrocarbons(PAHs)are promising nanocarbon materials with diverse optoelectronic properties,yet they also pose concerning environmental and health risks.Despite the ubiquity of PAHs in the environment(crude oil,emissions,and biomass),most supermolecules rely on heteroatoms for stability.We discovered and characterized a family of all-hydrocarbon,all-π-conjugated[n]cycloparaphenylene-PAH host–guest complexes.We built a theoretical framework to rapidly select these complexes and predict their stabilities,driven exclusively by CH–πinteractions.More than a dozen complexes were confirmed experimentally and assembled directly from commercially available compounds.This motif offers a versatile way to combine the advantageous properties of organic semiconductors with the rich dynamic,stereochemical,stimulus-responsive,and stressdissipative behavior of host–guest complexes,while creating new opportunities for bespoke PAH separation or remediation materials.

Wide-range color-tunable afterglow emission by the modulation of triplet exciton transition processes based on buckybowl structure

Buckybowl structures as non-uniform electrostatic potential distributions of poly-cyclic aromatic materials show a unique photoelectric performance.In this work,OTC was utilized for dynamic modulation of triplet exciton transition processes.Five host molecules with different functional units were selected,thus providing dif-ferent intermolecular interactions in the host/guest systems.Therefore,the delayed emissions were regulated from 536 to 624 nm via the tuning of the triplet exciton transition processes of OTC in different hosts.Experimental data and theoretical calculations revealed that the varied triplet transition behaviors resulted from the competition between the intersystem crossing(ISC)process of OTC-monomer and the reverse intersystem crossing(RISC)process of OTC-aggregates.This work proves the superior structure of buckybowl-based luminophore for controlling triplet exciton transition processes and supplies a new perspective for persistent afterglow luminophore design.

Supramolecular engineering of cell membrane vesicles for cancer immunotherapy

The clinical translation of nanomedicines has been strongly hampered by the limitations of delivery vehicles,promoting scientists to search for novel nanocarriers.Although cell membrane-based delivery systems have attracted extensive attention,further functionalizations are urgently desired to augment their theranostic functions.We propose a cell-friendly supramolecular strategy to engineer cell membranes utilizing cyclodextrin-based host–guest molecular recognitions to fix the defects arising from chemical and genetic modifcations.In this study,the supramolecular cell membrane vesicles(SCMVs)specifcally accumulate in tumors,benefting from tumor-homing capability and the enhanced permeability and retention effect.SCMVs co-delivering indocyanine green and an indoleamine 2,3-dioxygenase inhibitor effectively ablate tumors combining photodynamic therapy and immunotherapy.Driven by host–guest inclusion complexation,SCMVs successfully encapsulate resiquimod to repolarize tumor-associated macrophages into M1 phenotype,synergizing with immune checkpoint blockade therapy.This supramolecular engineering methodology based on noncovalent interactions presents a generalizable and cell-friendly tactic to develop living cell–originated nanomaterials for precise cancer therapy.

High-Performance n-Hexane Purification by Nonporous Adaptive Crystals of Leaning Pillar[6]arene

The production of high-purity n-hexane under mild conditions is of great significance in both the petrochemical industry and synthetic chemistry.Here,we report an easy-to-operate and energy-efficient n-hexane purification strategy using nonporous adaptive crystals of perethylated leaning pillar[6]arene(EtLP6).Adaptive EtLP6 crystals preferentially absorb n-hexane over other branched or cyclic C6 alkanes with similar boiling points.This selectivity arises from the different thermodynamic stabilities and variabilities of EtLP6 crystalloids loaded with n-hexane and other C6 alkanes.Moreover,the reversible transformations between the nonporous guest-free and n-hexane-containing structures make the EtLP6 crystals highly recyclable.

New Insights into the Ion-Specific Behaviors and Design Strategies for Ion–πInteractions

Ion–πinteractions play a critical role in many important biological processes,such as gene expression,nicotine addiction,ion channel function,and so on,through recognizing specific ions by the receptors.However,widely used models,such as electrostatic potential and quadrupole moment,either treat ions as point charges or consider arenes only such that the key role of the information carried by ions is rarely discussed.Here,we shed light on the ion specificities in ion–πinteractions by correlating binding energies to a new model,namely the orbital electrostatic energy(OEE),which describes the electrostatic properties of both ions and theπsystems in detail via electron density distributions on orbitals.With this more detailed descriptor of electrostatics,new insights behind several important experimental and theoretical behaviors of ion–πinteractions are revealed,which will provide a deeper understanding of molecular recognition and communication through ion–πinteractions.On top of the OEE model,an ion-specific design strategy is proposed.