Arene Derivatives Research Articles

Biologically active calixarene phosphonic acids

Phosphorylated derivatives of organic compounds are known to be capable of inhibiting the activities of enzymes and other proteins responsible for key metabolic pathways. In this connection, the calixarene phosphonic acids are of interest as macrocyclic agents interacting with targets that may be involved in pathological cellular processes. This review presents a literature survey on the synthesis and properties of calix[4]arene phosphonic acids as inhibitors of alkaline phosphatases, protein tyrosine phosphatases, Na,K-ATPase, nucleotide pyrophosphatase/phosphodiesterase 1, and some other enzymes and proteins. Brief information is also given about the inhibitory activity of calix[4]arene derivatives bearing alkyl phosphonate or phosphinic acid groups

Near-Infrared-Responsive Choline-Calix[4]arene-Gold Nanostructures for Potential Photothermal Cancer Treatment

The development of novel chemical approaches for the fabrication of gold nanostructures with localized surface plasmon resonance (LSPR) falling in the near-infrared (NIR) region is one challenging topic in nanomaterials science. Due to their optical and photothermal properties triggered by light excitation in the therapeutic window (λmax = 650–1300 nm), gold-based nanostructures are appealing candidates in anticancer nanomedicine. Here, we report a novel method to prepare water-dispersible gold nanostructures with NIR-LSPR (λmax = 600–1000 nm) properties. The gold nanostructures were achieved in a single step by an unconventional method using NADH as a reducing agent and an amphiphilic choline-calix[4]arene derivative (CholCalix) forming micelles as a template. The CholCalix-Au nanostructures were characterized by UV–visible spectrophotometry, Raman spectroscopy, and atomic force microscopy. Agglomeration of the nanostructures due to multiple crosslinking interactions was observed and supported by modeling simulation. Effective anticancer photothermal-induced effect of the CholCalix-AuNPs was demonstrated on human breast cancer cells irradiated with biofriendly light at 808 nm.

A novel AIEE pillar[5]arene-based conjugated oligomer as paraquat fluorescence turn-off sensor

A novel linear conjugated oligomer (Co-P[5]TPE) based on pillar[5]arene derivative as recognition group and tetraphenylethylene (TPE) unit as fluorophore was designed and synthesized. The Co-P[5]TPE showed aggregation-induced emission enhancement (AIEE) effect in the mixture of dimethyl sulfoxide (DMSO) and water, reaching the maximum fluorescence intensity while the fraction of water was 30%. In the DMSO/H2O solution (VDMSO/Vwater = 7/3), the oligomer sensor displayed “turn-off” fluorescence response (1–I/I0 = 98.7%) towards paraquat (PQ) over other competitive guests. The detection limit (LOD) was 1.54 × 10−8 M and the Stern-Volmer constant (KSV) was determined as 2.144 × 104 M−1 calculating via fluorescent titration experiments. Therefore, the Co-P[5]TPE has highly selective, sensitive and anti-interference properties for sensing PQ. Moreover, the recognition mechanism was specifically investigated through transmission electron microscopy (TEM), dynamic light scattering (DLS) and theoretical calculations involving frontier orbitals (HOMO and LUMO), electrostatic potential (ESP), and the noncovalent interaction (NCI). The cooperation of host-guest chemistry and photoinduced electron transfer (PET) can achieve fluorescence quenching of the chemosensor Co-P[5]TPE for PQ. In addition, the sensor can be used for PQ detection in practical sample.

Metal (Na+, K+, Cs+) Template Effect–Controlled Synthesis of Stereoisomers of Tetrasubstituted (Thia)calix[4]arene Derivatives Containing Sulfonatoalkyl Moieties on the Lower Rim

Metal (Na+, K+, Cs+) Template Effect–Controlled Synthesis of Stereoisomers of Tetrasubstituted (Thia)calix[4]arene Derivatives Containing Sulfonatoalkyl Moieties on the Lower Rim

Study on the Coordination of Cd Ion with Perhydroxylated Hetero-N and Hetero-S Calixtetraarene Derivatives

To explore the best hybrid calixarene for cadmium ion capture, the B3LYP method in density functional theory (DFT) was used to optimize the structure and infrared vibration data of the complexes formed by each fully hydroxylated heteroN and heteroS calixtetraarenes with Cd ions. The stability of the structure of each complex was verified. At the same time, the structural characteristics of each complex were analyzed. A comparative study on the binding ability of different numbers of hybrid calix [4] arene derivatives to Cd ions was carried out, and the complexes that best bound to Cd ions were obtained. For example, the binding capacity of hetero S-calix [4] arenes to Cd ions is greater than that of non-hybrid complexes and hetero-N complexes to Cd ions. More interestingly, as the number of S atoms in the hetero S increases, the binding ability to Cd becomes stronger.

Solid Lipid Nanoparticles Based on Monosubstituted Pillar[5]arenes: Chemoselective Synthesis of Macrocycles and Their Supramolecular Self-Assembly

Novel monosubstituted pillar[5]arenes with one or two terminal carboxyl groups were synthesized by the reaction of succinic anhydride with pillar[5]arene derivative containing a diethylenetriamine function. The ability for non-covalent self-assembly in chloroform, dimethyl sulfoxide, as well as in tetrahydrofuran-water system was studied. The ability of the synthesized macrocycles to form different types of associates depending on the substituent nature was established. The formation of stable particles with average diameter of 192 nm in chloroform and of 439 nm in DMSO was shown for pillar[5]arene containing two carboxyl fragments. Solid lipid nanoparticles (SLN) based on monosubstituted pillar[5]arenes were synthesized by nanoprecipitation in THF-water system. Minor changes in the structure of the macrocycle substituent can dramatically influence the stability and shape of SLN (spherical and rod-like structures) accordingly to DLS and TEM. The presence of two carboxyl groups in the macrocycle substituent leads to the formation of stable spherical SLN with an average hydrodynamic diameter of 364-454 nm. Rod-like structures are formed by pillar[5]arene containing one carboxyl fragment, which diameter is about of 50-80 nm and length of 700-1000 nm. The synthesized stable SLN open up great prospects for their use as drug storage systems.

Intramolecular Through-Space Interactions Induced Emission of Pillar[4]arene[1]dicyanobenzene

Macrocycles modified with donor (D)–acceptor (A) motifs are generally believed as advanced organic fluorophores with exceptional photophysical properties. However, it is still necessary to develop intrinsic D–A-type macrocycles without complicated modifications due to their significant implications in fabricating high-performance emissive materials. Herein, we report on the photoluminescence properties of pillar[4]arene[1]dicyanobenzene (P5-2CN), a pillar[5]arene derivative containing one p-phenylene dicyano unit. The rigid pillar conformation and nonconjugated architecture endow P5-2CN with unanticipated intramolecular through-space charge transfer (TSCT) and aggregation-induced emission properties, by which the ratio of locally excited state emission and TSCT emission can be easily affected by their residing environment. Intriguingly, P5-2CN solid powder displays a profound vaporchromic behavior for common nitrile vapors with different hydrocarbon chain lengths. Experimental and theoretical analyses reveal that intramolecular through-space conjugation is critical for such unusual photoluminescence.

Adsorption of Pb(II) on Calix[4]arene Derivatives: Kinetics and Isotherm Studies

This study aims to investigate the application of two calix[4]arene derivatives named 5,11,17,23-tetra-(t-butyl)-25,26,27,28-tetrahydroxycalix[4]arene (TBCA) and 5,11,17,23-tetra-(t-butyl)-26,27,28-tribenzoyloxycalix[4]arene (TBMTCA) as adsorbents of Pb(II) from aqueous solution in a batch system. Adsorption was carried out by varying pH solution, exposure time, and concentration. The kinetics was evaluated based on the adsorption in various exposure times using the Lagergren and Ho equations, while the isotherms were analyzed based on the adsorption in various Pb(II) concentrations using the Langmuir and Freundlich equations. Furthermore, the isotherm model showed the Pb(II) adsorption of TBCA and TBMTCA followed Langmuir model with a capacity of 137.29 and 128.46 mg/g, respectively. Based on the adsorption capacity, both adsorbents are the potential for the removal of heavy metal cations from polluted water.

Bifunctional Receptor Based on Calix[4]arene with Chromone Groups as An Efficient Colorimetric Sensor for Co2+, Cu2+, CN− and F−

AbstractNew calix[4]arene derivatives based on chromone linked through a thiosemicarbazone bridge have been designed and synthesized. It has been determined by UV‐visible absorption and IR‐spectroscopic study that molecular receptors are efficient for recognition of cations (Co2+, Cu2+, Ni2+ and Zn2+) and anions (F− and CN−), because calixarene plays a role as a molecular platform and the interaction is explained by the presence of the thiosemicarbazone bridge bound to chromone. The sensors showed selective colorimetric changes with cobalt (II), copper (II), cyanide and fluoride ions. The detection limits of 0.19 to 0.70 mg L−1 and the association constants ranging between 1.28×104 and 9.87×104 mol−1L can be estimated for these three sensors.

A novel material based on an antibacterial choline-calixarene nanoassembly embedded in thin films

Supramolecular chemistry is one of the current strategies for producing advanced materials. With the aim to develop new Thin-Films with antibacterial activity, we embedded an amphiphilic choline-calix[4]arene possessing antibacterial properties in polymeric Thin-Films based on polyether-co-amide matrix (Pebax®2533). The loading of the calix[4]arene derivative in the film was performed by solution casting. The amount of calixarene additive in the films was in the range of 0.5–5 wt%. The self-supported Thin-Films were characterized by investigating phase miscibility, morphology, spectral properties, and gas transport. The release of the calixarene derivative from the films was studied in a biomimetic medium as PBS (10 mM, pH 7.4). The presence of the additive did not affect the thermal stability of the copolymer, whereas it induced an increase in crystallinity, wettability, and gas permeability of the blend films according to its concentration. The antibacterial activity of the films was evaluated in vitro against Escherichia coli and Staphylococcus aureus strains, representative of Gram-negative and Gram-positive bacteria. The developed films displayed antibacterial activity against both strains. In particular, Pebax® − 5 wt% Chol-Calix caused within 10 h a reduction in E. coli and S. aureus of 2.57 and 2 log CFU/mL, respectively. The potential toxicity of the films was also tested on mouse embryonic fibroblasts NIH/3T3. Pebax®2533/calixarene derivative combination appears a promising approach for the development of novel flexible antibacterial materials.Graphical abstract

Synthesis, molecular docking and antiproliferative activity of upper rim modified azo calix[4]arene derivatives

Synthesis, molecular docking and antiproliferative activity of upper rim modified azo calix[4]arene derivatives

Synthesis of stimuli-responsive pillararene-based supramolecular polymer materials for the detection and separation of metal ions

A stimuli-responsive supramolecular polymer network (G-(CN)2⊂BXDSP5) with aggregation-induced emission (AIE) properties has been efficiently constructed by host–guest interactions between pillar[5]arene derivative BXDSP5 and a homoditopic guest G-(CN)2, which shows not only excellent fluorescence properties due to the AIE effect but also desirable ion-sensing abilities in both solution and solid states, holding great potential in the applicable fluorescence detection for Fe3+. The resultant G-(CN)2⊂BXDSP5 can be transformed into supramolecular polymer gel at high concentration via multiple noncovalent interactions, showing multi-stimuli-responsiveness in response to temperature change, mechanical force, and competitive agent. Meanwhile, the xerogel of supramolecular polymer material has been successfully used to remove Fe3+ from water with high adsorption efficiency. In addition, an ion-responsive film based on supramolecular polymer has also been developed, which can serve as a practical and convenient fluorescence test kit for detecting Fe3+.

Pillar[n]arene-Mimicking/Assisted/Participated Carbon Nanotube Materials.

The recent progress in pillar[n]arene-assisted/participated carbon nanotube hybrid materials were initially summarized and discussed. The molecular structure of pillar[n]arene could serve different roles in the fabrication of attractive carbon nanotube-based materials. Firstly, pillar[n]arene has the ability to provide the structural basis for enlarging the cylindrical pillar-like architecture by forming one-dimensional, rigid, tubular, oligomeric/polymeric structures with aromatic moieties as the linker, or forming spatially “closed”, channel-like, flexible structures by perfunctionalizing with peptides and with intramolecular hydrogen bonding. Interestingly, such pillar[n]arene-based carbon nanotube-resembling structures were used as porous materials for the adsorption and separation of gas and toxic pollutants, as well as for artificial water channels and membranes. In addition to the art of organic synthesis, self-assembly based on pillar[n]arene, such as self-assembled amphiphilic molecules, is also used to promote and control the dispersion behavior of carbon nanotubes in solution. Furthermore, functionalized pillar[n]arene derivatives integrated carbon nanotubes to prepare advanced hybrid materials through supramolecular interactions, which could also incorporate various compositions such as Ag and Au nanoparticles for catalysis and sensing.

Thiacalix[4]arene-based complex with Co(II) ions as electrode modifier for simultaneous electrochemical determination of Cd(II), Pb(II), and Cu(II).

A complex [Co4(TCTA)2(H2O)8]∙10H2O (Co-TCTA) based on thiacalix[4]arene derivative has been synthesized for the first time using the solvothermal method. The glassy carbon electrode (GCE) modified with Co-TCTA (Co-TCTA/GCE) could simultaneously determine Cd2+, Pb2+, and Cu2+ at around - 0.75V, - 0.60V, and - 0.10V (vs. ref. Ag/AgCl) and had good stability, selectivity, and reproducibility with relative standard deviation (RSD) of 4.4% for Cd2+, 1.4% for Pb2+, and 5.4% for Cu2+. Co-TCTA/GCE showed wide linear range of 0.4-8.0μM for Cd2+, 0.4-7.0μM for Pb2+, and 0.6-6.0μM for Cu2+ when three ions were determined simultaneously. The limits of detection (LODs) of Cd2+, Pb2+, and Cu2+ were 0.071μM, 0.022μM, and 0.021μM, respectively. Moreover, the sensor was used to determine three ions in lake water sample with satisfactory recoveries of 93.6-93.8% for Cd2+, 93.8-103.3% for Pb2+ and 94.6-95.3% for Cu2+. The good adsorption capacity of Co-TCTA and Co(II)/Co(0) circular mechanism on the surface of the electrode were proposed to enhance the electrochemical signals. This work enriched the theoretical research on the complexes for the determination of heavy metal ions.

New Synthetic Route to Water-Soluble Prism[5]arene Hosts and Their Molecular Recognition Properties.

We report that the direct macrocyclization of naphthalene monomers bearing ethyl ester functional groups delivers prism[5]arene derivatives, which can be deprotected to yield water-soluble prism[5]arenes (H1 and H3). 1 H NMR spectroscopy showed that dicationic guests bind with the hydrophobic cores buried inside the anisotropic magnetically shielding cavity. Isothermal titration calorimetry measurements showed that H1 and H3 are high-affinity hosts in PBS-buffered water with Ka values exceeding 109 M-1 for a select guest. The complexation events are driven by the non-classical hydrophobic effect, CH⋅⋅⋅π interactions, and electrostatic interactions. Host H1 displays somewhat higher affinity toward a common guest than pillar[6]arene bearing carboxylic acid functional groups but is significantly less potent than pillar[6]arene bearing sulfate groups. H1 and H3 should be considered alongside other high affinity hosts for a variety of chemical and biological applications.

A study on the antibacterial activity and antimicrobial resistance of pyridinium cationic pillar[5]arene against Staphylococcus aureus and Escherichia coli.

An increasing number of infections caused by multidrug-resistant (MDR) Staphylococcus aureus （S. aureus） and Escherichia coli （E. coli） have severely affected human society. Thus, it is essential to develop an alternative type of antibacterial agents that has a different bacterial resistance mechanism from that of traditional antibiotics. After the synthesis and structural characterization of a cationic pillar[5]arene with pyridinium groups (PP5), the antibacterial and antibiofilm activities as well as its microbial resistance were systematically investigated. In-depth evaluation of biological studies revealed that PP5 was an active antibacterial agent, with surprising antibiofilm formation ability against E. coli and S. aureus. From the results of differential scanning calorimetry and transmission electron microscopy, it was concluded that the microbicidal activity of PP5 was due to the physical disruption of the pathogen's membrane and the subsequent leakage of cytoplasmic components, which could greatly reduce the rapid generation of resistance. It was presented that the easily available PP5 has high activity to inhibit Gram-positive and Gram-negative bacteria and/or their biofilms with low cytotoxicity. This pillar[5]arene derivative can be used as a good candidate for controlling drug-resistant pathogenic bacterial infections and treating MDR bacteria.

A highly selective fluorescence probe for Co2+ or Cu2+ detection based on a new tetraquinoline-substituted calix[4]arene derivative

A new calixarene derivative (AlQuin-Calix) bearing two quinoline groups at its lower rim was synthesized at cone conformation. Then, upon functionalization of AlQuin-Calix with two more quinoline groups resulted with a novel calixarene-based fluorescent chemosensor (TetQuin-Calix) at partial cone conformation. The structures of all calixarene derivatives were duly characterized by spectroscopic methods such as FTIR, 1H NMR, 13C NMR, ESI-MS and elemental analysis. Moreover, ion sensing properties of AlQuin-Calix and TetQuin-Calix against different cations such as Co2+, Cu2+, Ni2+, Zn2+ and Ba2+ were evaluated. It was found that the calixarene-based chemosensor (TetQuin-Calix) exhibits remarkable affinity and high selectivity for Cu2+ and Co2+ in 50% water-CH3CN, while AlQuin-Calix provides an efficient chemosensor property towards only Co2+ ion among others. The fluorescence of TetQuin-Calix, with excitation/emission peaks at 268/397 nm, is quenched by Cu2+ or Co2+ ions. The limits of detection of TetQuin-Calix for Cu2+ and Co2+ ions were estimated to be 0.75 and 0.72 μM, respectively. Besides, stoichiometry, and binding constant in terms of the quenching mechanism were also determined using fluorescence data.

Transition metals of arene derivatives with functionalized ionic liquid: DFT investigation, biological applications and electrochemical behavior of complexes

Mononuclear transition metal complexes based on ionic liquid have been prepared and characterized in detail. The biological properties of the three complexes were evaluated using radical scavenging activity, reducing power, antibacterial effect, DNA binding and cleavage activity. Among the complexes, [3-[(2R)-2-({[dichloro(η6-benzene)ruthenium]diphenylphosphanyl}oxy)-2-phenylethyl]-1-methyl-1H-imidazol-3-ium chloride] (4), demonstrated the highest radical scavenging (64.7 %) and reducing power activity (0.467) at 200 μg/ml concentration. The highest zone of inhibition was obtained from [3-[(2R)-2-({[dichloro(η6-p-cymene)ruthenium]diphenyl phosphanyl}oxy)-2-phenylethyl]-1-methyl-1H-imidazol-3-ium chloride] (3), against Bacillus cereus as 14 mm. Furthermore, all complexes were determined to have DNA binding and cleavage activities. Furthermore, theoretical DFT computations have also been carried out for the cationic complexes, to obtain minimum energy configuration of molecules. The effects of the chemical structures of three cationic complexes were also examined in relation to the variable property of electron-donating ligands for ruthenium-based complexes and iridium complex and their potential energy levels in ground and excited states HOMO and LUMO were determined.

Discrete Macrocycles with Fixed Chirality and Two Distinct Sides: Dipole‐Dependent Chiroptical Response

AbstractControl of symmetry is fundamental in molecular design with aimed properties. Herein we report a set of chiroptical C5‐symmetric molecules with variable dipolar structures based on a rim‐differentiated cylindrical macrocycle, pillar[5]arene. Incorporation of electron‐withdrawing ester groups formed an explicit two‐sided structure, leading to increase in response wavelength and luminescence efficiency. On the other hand, chiroptical measurement of separated enantiomers revealed that such a dipolar character diminished dissymmetry of the electronic transitions. By suppressing the dipole, the dissymmetry factor for luminescence was enhanced from 0.4×10−3 to 5.1×10−3 in a less dipolar methoxy‐substituted molecule, which was larger than reported pillar[5]arene derivatives without C5‐symmetry around one order of magnitude.

Discrete Macrocycles with Fixed Chirality and Two Distinct Sides: Dipole-Dependent Chiroptical Response.

Control of symmetry is fundamental in molecular design with aimed properties. Herein we report a set of chiroptical C5 -symmetric molecules with variable dipolar structures based on a rim-differentiated cylindrical macrocycle, pillar[5]arene. Incorporation of electron-withdrawing ester groups formed an explicit two-sided structure, leading to increase in response wavelength and luminescence efficiency. On the other hand, chiroptical measurement of separated enantiomers revealed that such a dipolar character diminished dissymmetry of the electronic transitions. By suppressing the dipole, the dissymmetry factor for luminescence was enhanced from 0.4×10-3 to 5.1×10-3 in a less dipolar methoxy-substituted molecule, which was larger than reported pillar[5]arene derivatives without C5 -symmetry around one order of magnitude.