A Conjugated Polymeric Supramolecular Network with Aggregation-Induced Emission Enhancement: An Efficient Light-Harvesting System with an Ultrahigh Antenna Effect.

Superior artificial light-harvesting systems (ALHSs) require exceptional capacity in harvesting light and transferring energy. In this work, we report a novel strategy to build ALHSs with an unprecedented antenna effect (35.9 in solution and 90.4 in solid film). The ALHSs made use of a conjugated polymeric supramolecular network (CPSN), a crosslinked network obtained from the self-assembly of a pillar[5]arene-based conjugated polymeric host (CPH) and conjugated ditopic guests (Gs). The excellent performance of the CPSN could be attributed to the following factors: 1) The "molecular wire effect" of the conjugated polymeric structure, 2) aggregation-induced enhanced emission (AEE) moieties in the CPH backbone, and 3) high capacity of donor-acceptor energy transfer, and 4) crosslinked structures triggered by the host-guest binding between Gs and CPH. Moreover, the emission of the CPSN could be tuned by using different Gs or varying the host/guest ratio, thus reaching a 96 % sRGB area.

Pillar[5]arene-Diketopyrrolopyrrole Fluorescent Copolymer: A Promising Recognition and Adsorption Material for Adiponitrile by Selective Formation of a Conjugated Polypseudorotaxane.

Conjugated pillar[5]arene-diketopyrrolopyrrole copolymer (P1) is synthesized by the copolymerization of a difunctionalized pillar[5]arene and a diketopyrrolopyrrole-based monomer, which shows large extinction coefficients (1.1 × 104 m-1 cm-1 ) at 519 nm and strong emission at 587 nm. P1 exhibits very strong host-guest binding affinity towards adiponitrile but low binding affinity towards 1,4-dihalobutane and 1,4-bis(imidazol-1-yl)butane. Such an enhanced selectivity is first found in the polypseudorotaxane between pillararene and neutral guests in organic solution and is successfully used for the recognition and adsorption of adiponitrile by the formation of a P1-adiponitrile polypseudorotaxane.

A homologous membrane-camouflaged self-assembled nanodrug for synergistic antitumor therapy.

Limited success has been achieved in ferroptosis-induced cancer treatment due to the challenges related to low production of toxic reactive oxygen species (ROS) and inherent ROS resistance in cancer cells. To address this issue, a self-assembled nanodrug have been investigated that enhances ferroptosis therapy by increasing ROS production and reducing ROS inhibition. The nanodrug is constructed by allowing doxorubicin (DOX) to interact with Fe2+ through coordination interactions, forming a stable DOX-Fe2+ chelate, and this chelate further interacts with sorafenib (SRF), resulting in a stable and uniform nanoparticle. In tumor cells, overexpressed glutathione (GSH) triggers the disassembly of nanodrug, thereby activating the drug release. Interestingly, the released DOX not only activates nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) to produce abundant H2O2 production for enhanced ROS production, but also acts as a chemotherapeutics agent, synergizing with ferroptosis. To enhance tumor selectivity and improve the blood clearance, the nanodrug is coated with a related cancer cell membrane, which enhances the selective inhibition of tumor growth and metastasis in a B16F10 mice model. Our findings provide valuable insights into the rational design of self-assembled nanodrug for enhanced ferroptosis therapy in cancer treatment. STATEMENT OF SIGNIFICANCE: Ferroptosis is a non-apoptotic form of cell death induced by the iron-regulated lipid peroxides (LPOs), offering a promising potential for effective and safe anti-cancer treatment. However, two significant challenges hinder its clinical application: 1) The easily oxidized nature of Fe2+ and the low concentration of H2O2 leads to a low efficiency of intracellular Fenton reaction, resulting in poor therapeutic efficacy; 2) The instinctive ROS resistance of cancer cells induce drug resistance. Therefore, we developed a simple and high-efficiency nanodrug composed of self-assembling by Fe2+ sources, H2O2 inducer and ROS resistance inhibitors. This nanodrug can effectively deliver the Fe2+ sources into tumor tissue, enhance intracellular concentration of H2O2, and reduce ROS resistance, achieving a high-efficiency, precise and safe ferroptosis therapy.

Bio-inspired AIE pillar[5]arene probe with multiple binding sites to discriminate alkanediamines.

Two functionalized pillar[5]arenes (H1 and H2) with significant AIE properties were synthesized. H2 is an excellent probe to selectively detect specific alkanediamines owing to its multiple binding sites, which result in the enhancement of emission based on the AIE mechanism and the induced-fit mechanism, and provides a new strategy to develop probes with high selectivity and sensitivity.

Effect of scaffold structures on the artificial light-harvesting systems: a case study with an AIEE-active pillar[5]arene dyad.

Artificial light-harvesting systems were assembled as nanoparticles by an AIEE-active pillar[5]arene dyad H1, a complimentary fluorescent ditopic guest G2, and an optically silent tritopic guest G1 in water with CTAB. The formation of H1-G1 supramolecular polymers enhanced the G2 emission and the H1-G2 energy transfer, confirming the importance of scaffold structures in the systems.

Fluorescent-Cavity Host: An Efficient Probe to Study Supramolecular Recognition Mechanisms.

Using fluorometry to study the interactions between guests and host cavities is often challenging, especially for hosts with small cavities because the fluorophore may not be close to the binding site. Therefore, it is critical to overcome this hurdle to broaden the applicability of fluorometry in supramolecular chemistry. Herein, we designed a fluorescent-cavity host (H1) by conjugating the binding site of a pillar[5]arene cavity and studied its host-guest recognition mechanism in the cavity. Distinct fluorescent responses of H1 were observed for cyano homologues: the fluorescence was enhanced for succinonitrile but quenched for malononitrile. Such an unusual phenomenon with such subtle difference in guest structure was attributed to the different host-guest interactions induced by the subtle difference of guest locations within the H1 cavity. Our results indicate that developing fluorescent-cavity hosts as probes will provide a powerful and insightful way to explore the exquisite detail of host-guest recognition, self-assembly, and molecular machinery.

Stronger host-guest binding does not necessarily give brighter particles: a case study on polymeric AIEE-tunable and size-tunable supraspheres.

Supraspheres were prepared from a pillar[5]arene-based linear polymer (the host) and several multitopic guests. According to host-guest binding studies in nanosystems, the optical and structural properties (fluorescence capability, density, and particle size) of the nanoparticles were correlated not with the host-guest binding affinities, but with the relative fluorescence quantum yield.

A new highly selective fluorescent turn-on chemosensor for cyanide anion.

A new simple molecule, 2-((2-phenyl-2H-1,2,3-triazol-4-yl)methylene)malononitrile (M1), was synthesized successfully by the Knoevenagel condensation reaction between 2-phenyl-1,2,3-triazole-4-carboxaldehyde and malononitrile. The receptor M1 is highly sensitive and selective to cyanide anion due to the nucleophilic addition of cyanide anion with M1. Distinct changes on UV-vis and fluorescence spectra can be detected with the addition of cyanide anion to the DMSO solution of M1. Optical properties of M1 were scarcely affected by the addition of other common background anions (F(-), Cl(-), Br(-), I(-), SCN(-), OH(-), CO4(2-), H2PO4(-), SO4(2-), HSO4(-), AcO(-), and NO3(-)) under the same condition. The detection limit of CN(-) reaches ~1.43 µM by M1 and the presence of background anions brought very slight interference for the detection of CN(-).