Cis-Trans and Length-Selective Molecular Discrimination of Halogenated Organic Compounds by a Crystalline Hybrid Macrocyclic Arene

The development of adsorbents with robust molecular discrimination capabilities for halogenated organic compounds (HOCs) holds significant importance due to their potential in adsorptive separation and mitigation of associated health risks. In this study, we report a molecular discrimination behavior based on crystalline hybrid macrocyclic arene H, offering precise capture of cis-trans isomers and length-selective separation of HOCs. The activated H crystals (Hα) demonstrate exceptional discrimination and separation performance by selectively capturing trans-1,2-dichloroethylene (trans-DCE) from cis/trans-isomer mixtures with a high selectivity of 98.8%. Evidenced by single-crystal X-ray diffraction and density functional theory (DFT) calculations, this high adsorption selectivity arises from the formation of more stable complex crystals between H and the preferred guest trans-DCE. Moreover, Hα exhibits the ability to selectively trap size-matched 1,2-dibromoethane (DBE) from mixtures of alkylene dibromides with varying alkane-chain lengths, although their capture and separation are recognized to be difficult as a consequence of low-polarity bonds. The solid-state transformations between guest-free and guest-containing Hα crystals indicate their recyclability, showcasing promising prospects for potential applications.

Recent advances in the synthesis and applications of macrocyclic arenes

Macrocyclic arenes including calixarenes, resorcinarenes, cyclotriveratrylene, pillararenes and so on have emerged as highly attractive synthetic macrocyclic hosts due to their unique structures, facile functionalization, and broad range of applications. In recent years, there has been growing interest in the development of novel macrocyclic arenes composed of various aromatic building blocks bridged by methylene groups, which have found applications in various research areas. Consequently, the development of novel macrocyclic arenes has become a frontier and hot topic in supramolecular and macrocyclic chemistry. In this review, we feature the recent advances in the synthesis and applications of novel macrocyclic arenes that have emerged in the last decade. The general synthetic strategies employed for these macrocyclic arenes are systematically summarized, and their wide applications in molecular recognition and assemblies, molecular machines, biomedical science and functional materials are highlighted.

Resorc[4]arene-Modified Gold-Decorated Magnetic Nanoparticles for Immunosensor Development

In recent years, several efforts have been made to develop selective, sensitive, fast response, and miniaturized immunosensors with improved performance for the monitoring and screening of analytes in several matrices, significantly expanding the use of this technology in a broad range of applications. However, one of the main technical challenges in developing immunosensors is overcoming the complexity of binding antibodies (Abs) to the sensor surface. Most immobilizing approaches lead to a random orientation of Abs, resulting in lower binding site density and immunoaffinity. In this context, supramolecular chemistry has emerged as a suitable surface modification tool to achieve the preorganization of artificial receptors and to improve the functional properties of self-assembled monolayers. Herein, a supramolecular chemistry/nanotechnology-based platform was conceived to develop sensitive label-free electrochemical immunosensors, by using a resorcarene macrocycle as an artificial linker for the oriented antibody immobilization. To this aim, a water-soluble bifunctional resorc[4]arene architecture (RW) was rationally designed and synthesized to anchor gold-coated magnetic nanoparticles (Au@MNPs) and to maximize the amount of the active immobilized antibody (Ab) in the proper "end-on" orientation. The resulting supramolecular chemistry-modified nanoparticles, RW@Au@MNPs, were deposited onto graphite screen printed electrodes which were then employed to immobilize three different Abs. Furthermore, an immunosensor for atrazine (ATZ) analysis was realized and characterized by the differential pulse voltammetry technique to demonstrate the validity of the developed biosensing platform as a proof of concept for electrochemical immunosensors. The RW-based immunosensor improved Ab_ATZ loading on Au@MNPs and sensitivity toward ATZ by almost 1.5 times compared to the random platform. Particularly, the electrochemical characterization of the developed immunosensor displays a linearity range toward ATZ within 0.05-1.5 ng/mL, a limit of detection of 0.011 ng/ml, and good reproducibility and stability. The immunosensor was tested by analyzing spiked fortified water samples with a mean recovery ranging from 95.7 to 108.4%. The overall good analytical performances of this immunodevice suggest its application for the screening and monitoring of ATZ in real matrices. Therefore, the results highlighted the successful application of the resorc[4]arene-based sensor design strategy for developing sensitive electrochemical immunosensors with improved analytical performance and simplifying the Ab immobilization procedure.

Hybrid[4]arenes with anthracene units and tuneable cavities

Acid catalyzed condensation between tetramethoxyanthracenes and formaldehyde in the presence of additional benzene-based building blocks leads to hybrid macrocyclic products that are further modified by the Diels–Alder reaction with benzyne to obtain macrocycles with expanded cavities.