A novel hybrid macrocyclic receptor based on bile acid and calix[4]arene frameworks for metal ion recognition

Molecular vessels from preorganised natural building blocks

Supramolecular vessels emerged as tools to mimic and better understand compartmentalisation, a central aspect of living matter. However, many more applications that go beyond those initial goals have been documented in recent years, including new sensory systems, artificial transmembrane transporters, catalysis, and targeted drug or gene delivery. Peptides, carbohydrates, nucleobases, and steroids bear great potential as building blocks for the construction of supramolecular vessels, possessing complexity that is still difficult to attain with synthetic methods - they are rich in functional groups and well-defined stereogenic centers, ready for noncovalent interactions and further functions. One of the options to tame the functional and dynamic complexity of natural building blocks is to place them at spatially designed positions using synthetic scaffolds. In this review, we summarise the historical and recent advances in the construction of molecular-sized vessels by the strategy that couples synthetic predictability and durability of various scaffolds (cyclodextrins, porphyrins, crown ethers, calix[n]arenes, resorcin[n]arenes, pillar[n]arenes, cyclotriveratrylenes, coordination frameworks and multivalent high-symmetry molecules) with functionality originating from natural building blocks to obtain nanocontainers, cages, capsules, cavitands, carcerands or coordination cages by covalent chemistry, self-assembly, or dynamic covalent chemistry with the ultimate goal to apply them in sensing, transport, or catalysis.

Bile acid-based receptors and their applications in recognition

Ion recognition has attracted great attention in the past decades because of its important role in biology, medicine, environment, and chemistry. The combination of rigidity, curved structure and amphiphilic nature makes bile acids a host system for ion recognition. In addition, the availability of hydroxyl groups in bile acids can be used for further derivatization to develop various ion recognition receptors. The detection of ions is revealed by the binding constant k_a value, log approach, and UV-visible or ¹H NMR titration, while visual detection is determined by gel-phase transition, colorimetric and fluorescent probes. In this review, we have discussed the bile acid-based receptors and their ion-recognition capability. These bile acid-based systems have the potential for the development of anion transport for biological activity.

Synthesis of Core-Shell Magnetic Supramolecular Nanocatalysts based on Amino-Functionalized Calix[4]arenes for the Synthesis of 4H-Chromenes by Ultrasonic Waves

One of the most common phenol-formaldehyde cyclic oligomers from hydroxyalkylation reactions that exhibit supramolecular chemistry are calixarenes. These macrocyclic compounds are qualified to act as synthetic catalysts due to their specific features including being able to form host-guest complexes, having unique structural scaffolds and their relative ease of chemical modifications with a variety of functions on their upper rim and lower rim. Here, a functional magnetic nanocatalyst was designed and synthesized by using a synthetic amino-functionalized calix[4]arene. Its catalytic activity was evaluated in a one-pot synthesis of 2-amino-4H-chromene derivatives. Besides, this novel magnetic nanocatalyst was characterized by spectroscopic and analytical techniques such as FT-IR, EDX, FE-SEM, TEM VSM, XRD analysis.

Recent methods for diversification of bile acids and related steroids towards supramolecular

Bile acids (BAs) are a class of steroidal surfactants that have been studied as building blocks for constructing useful chemical frameworks. These starting materials have rigid structures with defined hydrophobic and hydrophilic faces, which promotes self-assembly in well-defined chemical architectures. The BA scaffolds can undergo a variety of transformations to introduce a range functionalities with practical applications. These functionalized derivatives have seen application in pharmacology, supramolecular chemistry, and nanotechnology in roles such as surfactants, gelators, drug conjugates, or chemical detectors. This review seeks to highlight recent synthetic methods utilizing BAs to construct useful chemical structures and their application in supramolecular chemistry.