Calixarene-engineered surfaces and separation science

RP-HPLC Study of the Complexation of Acetamiprid, Imidacloprid and Carboxin Guest Molecules With Thiophosphorylated Calix [6] Arene in Dimethylformamide-Acetonitrile-Water Mobile Phase

Reversed-phase high-performance liquid chromatography was used to study the host-guest complexation of thiophosphacalixarenes (TPC 1-3) with acetamiprid, imidacloprid and carboxin as guests. The Onyx Monolithic C 18 column (150 × 0.1 mm) and Phenomenex® were used with UV detection at 254 nm. The mobile phase consisted of dimethylformamide-acetonitrile-water. The association constant of the 1:1 guest-host complexes was determined from the relationship between the retention factor of the guest and concentration of the thiophosphacalix [6] arene host in the mobile phase. The stability constants are influenced by size, nature, position and quantity of substituents in the benzene ring of the calixarene skeleton. The detection limits for TPC 1, TPC 2 and TPC 3 are 0.95, 1.20 and 1.40 μg/mL, while the quantification limits are 2.85, 3.60 and 4.20 μg/mL for TPC 1, TPC 2 and TPC 3, respectively.

Promises of anionic calix[n]arenes in life science: State of the art in 2023

Because they hold together molecules by means of non-covalent interactions - relatively weak and thus, potentially reversible - the anionic calixarenes have become an interesting tool for efficiently binding a large range of ligands - from gases to large organic molecules. Being highly water soluble and conveniently biocompatible, they showed growing interest for many interdisciplinary fields, particularly in biology and medicine. Thanks to their intrinsic conical shape, they provide suitable platforms, from vesicles to bilayers. This is a valuable characteristic, as so they mimic the biologically functional architectures. The anionic calixarenes propose efficient alternatives for overcoming the limitations linked to drug delivery and bioavailability, as well as drug resistance along with limiting the undesirable side effects. Moreover, the dynamic non-covalent binding with the drugs enables predictable and on demand drug release, controlled by the stimuli present in the targeted environment. This particular feature instigated the use of these versatile, stimuli-responsive compounds for sensing biomarkers of diverse pathologies. The present review describes the recent achievements of the anionic calixarenes in the field of life science, from drug carriers to biomedical engineering, with a particular outlook on their applications for the diagnosis and treatment of different pathologies.

Coumarin-Calix[4]arene Conjugate-Anchored SiO2 Nanoparticles as an Ultrasensor Material for Fe3+ to Work in Water, in Serum, and in Biological Cells

A coumarin-appended calixarene derivative ( CouC4A ) and a hybrid material generated by covalently linking this onto a silica surface ( CouC4A@SiO 2 ) were synthesized and were characterized by various analytical, spectroscopy, and microscopy methods. Both these materials are capable of sensing Fe3+ with greater sensitivity and selectivity. The sensitivity is enhanced by 30,000 fold on going from a simple solution phase to the silica surface with the limit of Fe3+ detection being 1.75 ± 0.4 pM when CouC4A@SiO 2 is used, and the sensing is partially reversible with phosphates, while it is completely reversible with adenosine 5'-triphosphate (ATP). While the calix precursor, CouC4A , has a limitation to work in water, anchoring this onto SiO2 endowed it with the benefit of its use in water as well as in buffer and thereby extends its application toward Fe3+ sensing even in the biorelevant medium such as fetal bovine serum and human serum. The hybrid material is biocompatible and shows ∼90% cell viability in the case of MDA-MB231 and 3T3 cell lines. CouC4A@SiO 2 functions as a reversible sensor for Fe3+ with the use of ATP in vitro as well as in biological cells. Thus, the inorganic-organic hybrid material, such as, CouC4A@SiO 2 , is an indispensable material for sensitive and selective detection of Fe3+ in a picomolar range in solution and in nanomolar to micromolar range in biorelevant fluids and biological cells, respectively.

Tetraphenylethylene-functionalized hexaphenylbenzene with unique conformation-driven selectivity for gas chromatographic separations

Tetraphenylethylene-functionalized hexaphenylbenzene composed of a neat aromatic hydrocarbon with unique conformation-driven selectivity for gas chromatographic separations.

Separation performance of p-tert-butyl(tetradecyloxy)calix[6]arene as a stationary phase for capillary gas chromatography

This work presents the first example of the utilization of p-tert-butyl(tetradecyloxy)calix[6]arene (C6A-C10) as a stationary phase for capillary gas chromatographic (GC) separation.

p-Nitro-tetradecyloxy-calix[4]arene as a highly selective stationary phase for gas chromatographic separations

Here, we report the first example of the utilization of p-nitro-tetradecyloxy-calix[4]arene (C4A-NO₂) as a stationary phase for capillary gas chromatographic (GC) separations.

Recent advances in mixed-mode chromatographic stationary phases

Mixed-mode phases have become very popular in the last decade, and the number of new mixed/multi-mode sorbents is growing fast. Unlike single-mode stationary phases, perfectly suited for the separation of the analytes possessing similar physicochemical properties, for instance reversed-phase chromatography for hydrophobic solutes, mixed-mode sorbents providing multimodal interactions can render better separation selectivity for complex mixtures of solutes differing significantly in their physicochemical characteristics. The most frequent modern mixed-mode stationary phases are di/tri-mode sorbents embracing the following interactions, hydrophobic, electrostatic (coulombic), and hydrophilic. According to their structures, it is possible to distinguish silica-based, polymer-based, hybrid, and monolithic mixed-mode stationary phases. Herewith, newly synthesized mixed-mode sorbents developed within the last two and half years are categorized, discussed, and summarized. The main attention is devoted to the description of the synthetic routes and characterization methods applied for the new stationary phases.

Host-Guest Chemistry in Layer-by-Layer Assemblies Containing Calix[n]arenes and Cucurbit[n]urils: A Review

This review provides an overview of the synthesis of layer-by-layer (LbL) assemblies containing calix[n]arene (CA[n]) and cucurbit[n]uril (CB[n]) and their applications. LbL assemblies, such as thin films and microcapsules, containing selective binding sites have attracted considerable attention because of their potential use in separation and purification, sensors for ions and molecules, and controlled release. CA[n]-containing LbL films have been prepared using sulfonated CA[n] and cationic polymers to construct chemical sensors and molecular containers. CA[n]-containing LbL films deposited on the surface of a porous support are useful as ion-selective membranes that exhibit selective permeability to monovalent ions over multivalent ions. CB[n]s have been used as molecular glues for the construction of LbL films and microcapsules by taking advantage of the strong affinity of CB[n]s to aromatic compounds. CB[n]s form a stable 1:1:1 ternary complex with electron-rich and electron-deficient molecules in LbL films to stabilize the assemblies. CB[n]-containing LbL films can also be deposited on the surfaces of micro templates and nanopore membranes to construct microcapsules for controlled release and nanochannels for selective ion transport, respectively.