Multiple Stimuli-Responsive Supramolecular Hydrogels Constructed by Decamethylcucurbit[5]uril-para-phenylenediamine Exclusion Complex

Circularly polarized luminescence from decamethylcucurbit[5]uril-triggered chiral supramolecular hydrogels

Fluorescence resonance energy transfer (FRET) is observed in the supramolecular hydrogels assembled by decamethylcucurbit[5]uril and (R/S)-BINAM upon the addition of sulforhodamine B, tuning the emission from blue-green to red. High circularly polarized luminescence asymmetry factor and near-white light emission are achieved, offering a new strategy for white CPL material design.

p-Phenylenediamine-Bridged Binder-Electrolyte-Unified Supramolecules for Versatile Lithium Secondary Batteries

The binder is an essential component in determining the structural integrity and ionic conductivity of Li-ion battery electrodes. However, conventional binders are not sufficiently conductive and durable to be used with solid-state electrolytes. In this study, a novel system is proposed for a Li secondary battery that combines the electrolyte and binder into a unified structure, which is achieved by employing para-phenylenediamine (pPD) moiety to create supramolecular bridges between the parent binders. Due to a partial crosslinking effect and charge-transferring structure of pPD, the proposed strategy improves both the ionic conductivity and mechanical properties by a factor of 6.4 (achieving a conductivity of 3.73 × 10-4 S cm-1 for poly(ethylene oxide)-pPD) and 4.4 (reaching a mechanical strength of 151.4 kPa for poly(acrylic acid)-pPD) compared to those of conventional parent binders. As a result, when the supramolecules of pPD are used as a binder in a pouch cell with a lean electrolyte loading of 2 µL mAh-1 , a capacity retention of 80.2% is achieved even after 300 cycles. Furthermore, when it is utilized as a solid-state electrolyte, an average Coulombic efficiency of 99.7% and capacity retention of 98.7% are attained under operations at 50 °C without external pressure or a pre-aging process.

Preparation and Biomedical Applications of Cucurbit[n]uril-Based Supramolecular Hydrogels

The cucurbit[n]uril supramolecular hydrogels are driven by weak intermolecular interactions, of which exhibit good stimuli responsiveness and excellent self-healing properties. According to the composition of the gelling factor, supramolecular hydrogels comprise Q[n]-cross-linked small molecules and Q[n]-cross-linked polymers. According to different driving forces, hydrogels are driven by the outer-surface interaction, the host-guest inclusion interaction, and the host-guest exclusion interaction. Host-guest interactions are widely used in the construction of self-healing hydrogels, which can spontaneously recover after being damaged, thereby prolonging their service life. The smart Q[n]s-based supramolecular hydrogel composed is a kind of adjustable and low-toxicity soft material. By designing the structure of the hydrogel or modifying the fluorescent properties, etc., it can be widely used in biomedicine. In this review, we mainly focus on the preparation of Q[n]-based hydrogels and their biomedical applications including cell encapsulation for biocatalysis, biosensors for high sensitivity, 3D printing for potential tissue engineering, drug release for sustained delivery, and interfacial adhesion for self-healing materials. In addition, we also presented the current challenges and prospects in this field.

Supramolecular Room-Temperature Phosphorescent Hydrogel Based on Hexamethyl Cucurbit[5]uril for Cell Imaging

The host-guest interaction between hexamethyl cucurbit[5]uril (HmeQ[5]) and 1,4-diaminobenzene (DB) was investigated, and a new low-molecular-weight supramolecular gel was prepared by a simple heating/mixing cooling method. The structure and properties of the supramolecular gel were characterized. Results revealed that DB molecules did not enter the cavity of HmeQ[5] and that hydrogen bonding between the carbonyl group at the HmeQ[5] port and the DB amino groups, together with dipole-dipole interactions and outer wall interactions, were the main driving forces for the formation of the supramolecular gel. The HmeQ[5]/DB gel system exhibits temperature sensitivity. The phosphor 6-bromo-2-naphthol (BrNp) was embedded in the gel to give the gel fluorescent phosphorescence double emission. The double emission ability at room temperature can be attributed to the ordered microstructure of the supramolecular gel, which effectively avoids the nonradiative transition of BrNp. Meanwhile, HmeQ[5]/DB-BrNp has good biocompatibility and low biotoxicity, which is compatible with HeLa cells to achieve cytoplasmic staining of HeLa in the red channel. The supramolecular gels constructed by this supramolecular assembly strategy not only have good temperature sensitivity but also extend the application of Q[n]s in biomedical fields.