Selective molecular recognition in water is routine for bioreceptors, but remains challenging for synthetic hosts. This is principally because noncovalent interactions are usually less efficient in aqueous environments. By mimicking the cavity feature of bioreceptors, Prof. Wei Jiang proposed and clarified the concept of "endo-functionalized cavity". Through situating polar binding sites into a deep hydrophobic cavity, we designed and synthesized several macrocyclic hosts, among which amide naphthotubes are the most representative. The hosts can selectively recognize various polar molecules including organic micropollutants, drug molecules, and chiral molecules in water by employing the hydrophobic effect and shielded hydrogen bonding. In addition, these biomimetic hosts have been applied in spectroscopic analysis, adsorptive separation and self-assembly. In this review, we provide an overview of recent advances on amide naphthotubes with special emphasis on the efforts of Jiang's group. We are convinced that these biomimetic macrocycles will make further contributions to supramolecular chemistry and beyond.

Supramolecular fluorescent sensors can address various detection and bioimaging issues related to the environment and human health.Indicator displacement assay(IDA)is a supramolecular fluorescence sensing method that can convert the chemical changes caused by molecular recognition into easily observed fluorescence signals.It provides a unique and innovative sensing method for the detection of analytes.In recent years,IDA based on non-covalent binding has been developed rapidly due to its advantages of high sensitivity,adjustability,real-time,and low synthesis effort.In order to meet the diverse needs of IDA development,a variety of supramolecular macrocyclic hosts have been involved in the construction of IDA sensors,such as calix[n]arenes,cucurbit[n]uril,pillar[n]arenes,etc.The recent research progress in this field based on different classes of macrocycles is briefly reviewed,focusing on the application in biochemical sensing,and providing a reference for the construction and application of novel fluorescent biochemical sensing platforms based on IDA in the future.

Hypochlorous acid (HClO) is used in food preservation. However, excessive HClO can deteriorate nutritional composition of food, compromise its quality, and potentially induce various diseases. Consequently, the development of multifunctional fluorescent probes for the sensitive and selective detection of HClO is highly anticipated for food safety. In this work, we designed a nanoprobe using N-aminomorpholine (AM)-functionalized bromine-doped carbon dots (Br-CDs-AM) for sensing HClO. This nanoprobe exhibits pH stability, strong resistance to photobleaching, superior long-term photostability (12 weeks), high sensitivity (19.3 nM), and an ultrarapid response (8 s) for detecting HClO residues in food matrices with percentage recovery (96.5 %-108 %) and RSDs less than 5.34 %. In addition, extremely low cytotoxicity and outstanding biocompatibility enable the nanoprobe to be used primarily for lysosome tracking and rapidly visualizing HClO in live cells. Thus, this study provides a new pathway to design unconventional nanoprobes for food safety assessment and subcellular organelle-specific imaging HClO.

Molecular recognition is ubiquitous in nature and plays a crucial role in numerous biological processes and supramolecular chemistry.Due to the significant weakening of specific non-covalent interactions(e.g.,hydrogen bonding)by the polar environment of water,the use of artificial macrocyclic hosts for molecular identification in the water is challenging.Tetralactam macrocycles are artificial macrocyclic hosts with polar binding sites inside the hydrophobic cavity,which can realize the recognition of hydrophilic molecules in the water by mimicking the molecular recognition of bioreceptors.Through the synergistic effect of hydrophobic effect and hydrogen bonds,it can selectively recognize drug molecules,saccharides,dyes,organic pollutants,disease markers and other substances in the aqueous environment.The research advances of tetralactam macrocycles in molecular recognition and application over the last 30 years are summarized,with a particular emphasis on its molecular recognition and application in the water,hoping to provide a reference for the development of tetralactam macrocycles in the future.

Artificial macrocycle with high binding selectivity in water is often challenging but urgently needed in various research and application areas. Herein, we report a new water-soluble biomimetic tetralactam macrocycle and realize the ultra-high selectivity to nucleosides over corresponding monophosphate nucleotides by rational modification. The introduction of charged groups at the periphery of endo-functionalized cavity makes the selectivity (guanosine to guanosine 5'-monophosphate) increase remarkably from 100 to 1119. Based on the ultra-high selectivity of biomimetic tetralactam macrocycle, the sensitive CD73 enzyme activity assay was then achieved through product-selective fluorescence indicator displacement assay. Furthermore, the capability of the proposed method for inhibitor screening was successfully displayed.

With the rapid urbanization and industrialization of human society, water pollution issues caused by the increasing types and quantities of organic micropollutants have become increasingly severe. It is very urgent but also challenging to develop the rapid and efficient method for water purification with a wide removal scope. Herein, a cross-linked polymer adsorbent was fabricated by adaptive tetralactam macrocycle for rapid and efficient removal of multiple types of organic micropollutants in water, including dyes, pharmaceuticals, pesticides, and hormones. The removal efficiencies for the 20 tested organic micropollutants with diverse structures, sizes, and charges are all larger than 95.9 % and approaching 99.9 %, and most of the adsorption processes were finished within 5 min. The well-preorganized and adaptive cavity of tetralactam macrocycle endows the polymer adsorbent with excellent adsorption performance even in extreme conditions. Moreover, the tetralactam macrocycle-crosslinked polymer adsorbent could be regenerated easily and the performance was maintained after 6 cycles. It is demonstrated that the as-developed polymer has great potential in the removal of various hazardous organic pollutants in water.

The separation and especially the removal of morpholine (MOR) impurities from N-ethyl morpholine (NEM) is of great significance in the fine chemical industry. Herein, we offer a novel strategy for the selective adsorption of MOR over NEM by tetralactam solids. The adsorbent realized the purification of NEM by adsorbing traces of MOR impurities, such that the purity can be improved from around 98% to over 99.5%. Single crystal structures indicate that N-H⋯O and N-H⋯N hydrogen bonding interactions are essential in the selective separation.

The safety of drinking water is vital for human health. In recent years, organic micropollutants (OMPs) in water have attracted much attention because they are toxic, non-degradable, easily migratable and have wide sources. Since 2017, inspired by the pioneering work on the adsorption removal of OMPs from water by porous polymerized β-cyclodextrins, the adsorption of OMPs in water by macrocycle-crosslinked polymers (MCPs) has received widespread attention. Classical macrocyclic hosts such as cyclodextrin, calixarene, pillararene and other emerging macrocycles have been employed for this purpose. This review encompasses the advancements on the removal of OMPs from water by MCPs, involving the building blocks of polymers, types of OMPs, the preparation and performance of each MCP. An overview of challenges and future research directions in this regard are also discussed.

An indicator displacement assay for colorimetric and fluorometric dual-mode detection of urinary uric acid (UA) was constructed using a water-soluble naphthalene-based tetralactam macrocycle and the phenoxazine dye, resorufin (RF). The visual detection of UA levels of volunteers was successfully realized using modified paper assays, which could be used for the home monitoring of urinary UA.

The development of novel lysosome-targetable fluorescence (FL) probes for visualizing intracellular HClO is of great significance for better exploring the function of HClO in pathophysiological processes. In this work, bromine-doped carbon dots (Br-CDs) were prepared using bromothymol blue as the precursor by a facile hydrothermal method. Br-CDs were covalently conjugated with N-aminomorpholine (AM) to afford the AM-functionalized Br-CDs (Br-CDs-AM) as a lysosome-targetable nanoprobe for subcellular organelle-specific HClO monitoring. The as-prepared Br-CDs-AM exhibits pH stability, strong resistance to photobleaching, superior long-term fluorescence stability (12 weeks), high sensitivity (19.3 nM), ultrarapid response (8 s), extremely low cytotoxicity, and outstanding biocompatibility. These favorable features enable the nanoprobe to be used primarily for the location tracking of lysosomes and to rapidly visualize endogenous and exogenous HClO in live cells. Thus, the study provides a new pathway to design nanoprobes based on Br-CDs-AM for subcellular organelle-specific imaging and for elucidating the complex biological functions of HClO.