Salt/current-triggered stabilization of β-cyclodextrins encapsulated host-guest low-molecular-weight gels

A crown ether embedded responsive π-gelator for transition from a one-component gel to a two-component gel

A novel fluorescent π-gelator, incorporating a crown ether with host-guest recognition capability and a photoactive cyanostilbene unit, was designed. This unique structure enables the successful transition from a one-component gel to a two-component gel and exhibits gel-sol transition behaviors under heat, ions, and light stimuli.

Protoboration of Alkynes and Miyaura Borylation Catalyzed by Low Loadings of Palladium

The versions of Miyaura borylation and protoboration of alkynes catalyzed by low loadings of palladium (400 mol ppm = 0.04 mol %) have been developed. These transformations have a broad substrate scope, good functional-group compatibility, and gram-scale synthetic ability.

Synthesis of novel epichlorohydrin cross-linked β-cyclodextrin functionalized with reduced graphene oxide composite adsorbent for treatment of phenolic wastewater

A novel composite consisting reduced graphene oxide-functionalized beta-cyclodextrin epichlorohydrin polymer (RGO-βCD-ECH) was synthesized for the treatment of phenolic wastewater. Batch study of phenolic pollutants (2,4-dichlorophenol, 2-chlorophenol, and phenol) was analyzed using the synthesized composite as an adsorbent from an aqueous solution. The optimized parameters were temperature 25 °C, adsorption time 60 min, solution pH 7, and dosage 0.25 g/L. The isotherm data were more suitably fitted by the Langmuir isotherm model. The maximum uptake for 2,4-dichlorophenol, phenol, and 2-chlorophenol was 702.853, 659.475, and 674.155 mg/g, respectively, at 25 ± 1 °C. The kinetic data for all the phenolic pollutants follow the pseudo-second-order model, and the rate was controlled by film diffusion. Thermodynamic data revealed that the process of removing phenolic pollutants is spontaneous and endothermic. The composite can be used up to five cycles with a small reduction in the removal. Adsorption performance of the synthesized composite for synthetic industrial effluents shows that up to 78% removal occurred in 60 min adsorption time. Based on the remarkably rapid adsorption and high adsorption capacity, the synthesized composite can be considered an efficient adsorbent for treating phenolic pollutants from wastewater.

Fluorescent Quinoline-Based Supramolecular Gel for Selective and Ratiometric Sensing Zinc Ion with Multi-Modes

A gelator 1 containing functional quinoline and Schiff base groups that could form organogels in DMF, DMSO, acetone, ethanol and 1,4-dioxane was designed and synthesized. The self-assembly process of geator 1 was characterized by field emission scanning electron microscopy (FESEM), UV-vis absorption spectroscopy, fluorescence emission spectroscopy, Fourier transform infrared spectroscopy(FTIR), X-ray powder diffraction (XRD) and water contact angle. Under non-covalent interactions, gelator 1 self-assembled into microbelts and nanofiber structures with different surface wettability. Weak fluorescence was emitted from the solution and gel state of 1. Interestingly, gelator 1 exhibited good selectivity and sensitivity towards Zn2+ in solution and gel states along with its emission enhancement and change. The emission intensity at 423 nm of solution 1 in 1,4-dioxane was slightly enhanced, and a new emission peak appeared at 545 nm along with its intensity sequentially strengthened in the titration process. The obvious ratiometric detection process was presented with a limit of detection (LOD) of 5.51 μM. The detection mechanism was revealed by a theoretical calculation and NMR titration experiment, which was that Zn2+ induced the transition from trans- to cis- of molecule 1 and further coordinated with 1. This study will introduce a new method for the construction of functional self-assembly gel sensors for the detection of Zn2+.

Multicharged cyclodextrin supramolecular assemblies

Multicharged cyclodextrin (CD) supramolecular assemblies, including those based on positively/negatively charged modified mono-6-deoxy-CDs, per-6-deoxy-CDs, and random 2,3,6-deoxy-CDs, as well as parent CDs binding positively/negatively charged guests, have been extensively applied in chemistry, materials science, medicine, biological science, catalysis, and other fields. In this review, we primarily focus on summarizing the recent advances in positively/negatively charged CDs and parent CDs encapsulating positively/negatively charged guests, especially the construction process of supramolecular assemblies and their applications. Compared with uncharged CDs, multicharged CDs display remarkably high antiviral and antibacterial activity as well as efficient protein fibrosis inhibition. Meanwhile, charged CDs can interact with oppositely charged dyes, drugs, polymers, and biomacromolecules to achieve effective encapsulation and aggregation. Consequently, multicharged CD supramolecular assemblies show great advantages in improving drug-delivery efficiency, the luminescence properties of materials, molecular recognition and imaging, and the toughness of supramolecular hydrogels, in addition to enabling the construction of multistimuli-responsive assemblies. These features are anticipated to not only promote the development of CD-based supramolecular chemistry but also contribute to the rapid exploitation of these assemblies in diverse interdisciplinary applications.

Wholly Visible-Light-Responsive Host-Guest Supramolecular Gels Based on Methoxy Azobenzene and β-Cyclodextrin Dimers

Much attention has been paid to construct photoresponsive host-guest supramolecular gels; however, red-shifting the responsive wavelength remains a formidable challenge. Here, a wholly visible-light-responsive supramolecular gel was fabricated through the host-guest interaction between a β-cyclodextrin (β-CD) dimer and a tetra-ortho-methoxy-substituted azobenzene (mAzo) dimer (binary gelator) in DMSO/H₂O (V/V = 8/2). The minimum gelation concentration of the low-molecular-weight binary gelator was 6 wt % measured via the tube inversion method. The substituted methoxy groups shifted the responsive wavelengths of trans-mAzo and cis-mAzo to the green and blue light regions, respectively. The host-guest interaction between mAzo and β-CD as the driving force for gelation was confirmed using the ¹H-NMR and 2D ¹H NOESY spectra. The supramolecular gel showed good self-supporting ability with a storage modulus higher than 10⁴ Pa. The release of Rhodamine B loaded in the gel as a model drug could be controlled by green light irradiation. We envisioned the potential applications of the wholly visible-light-responsive supramolecular compounds ranging from biomedical materials to smart materials.

PDA-cross-linked beta-cyclodextrin: a novel adsorbent for the removal of BPA and cationic dyes

In this study, 4,4'-(hexafluoroisopropene) diphthalic acid (PDA)-CD polymers containing β-cyclodextrin (CD) were synthesized for the adsorption of endocrine disrupting chemicals (EDCs) and dyes. It features great adsorption of bisphenol A (BPA), methylene blue (MB) and neutral red (NR). The maximum adsorption capacities of MB, NR and BPA can reach 113.06, 106.8 and 51.74 mg/g, respectively. The tandem adsorption results revealed that adsorptions of dyes and BPA onto PDA-CD polymer were two independent processes: non-polar BPA entrapment by cyclodextrin cavities while dyes were captured by the carboxyl groups and π-π stacking interactions. The adsorption processes performed well in a wide range of pH (4.0-10.0) and were not affected by fulvic acid (FA) and inorganic ions.