Calixarene Molecules Research Articles

Supramolecular self-assembled nanoparticles camouflaged with neutrophil membrane to mitigate myocardial ischemia/reperfusion (I/R) injury

The clinically restored blood supply post myocardial infarction (MI) will break the physiological and metabolic balance of the ischemic myocardial region, leading to a new injury known as myocardial ischemia/reperfusion (I/R) injury. Abundant oxygen brought by the fresh blood would trigger the damaged myocardium to produce excessive reactive oxygen species (ROS) and thereby inflammation along with the recruitment and infiltration of activated neutrophils and macrophages. Inspired by the active targeting process of inflammatory cells, a novel “neutrophil-like” nanoassembly (At@NQA) was prepared by modifying neutrophil membrane fragments onto At@QA NPs containing 1:1 (molar ratio) calixarene molecule (QA) and anti-inflammatory and anti-fibrotic atorvastatin calcium (At). Tail vein injection of the At@NQA could efficiently target the damaged myocardium, inhibit oxidative damage and inflammation, reduce myocardial fibrosis, increase myocardial troponin T (cTnT) and connexin 43 (Cx43) expression, and thus improve cardiac functions effectively.

A porous metal-organic cage liquid for sustainable CO2 conversion reactions

Porous liquids are fluids with the permanent porosity, which can overcome the poor gas solubility limitations of conventional porous solid materials for three phase gas-liquid-solid reactions. However, preparation of porous liquids still requires the complicated and tedious use of porous hosts and bulky liquids. Herein, we develop a facile method to produce a porous metal-organic cage (MOC) liquid (Im-PL-Cage) by self-assembly of long polyethylene glycol (PEG)-imidazolium chain functional linkers, calixarene molecules and Zn ions. The Im-PL-Cage in neat liquid has permanent porosity and fluidity, endowing it with a high capacity of CO2 adsorption. Thus, the CO2 stored in an Im-PL-Cage can be efficiently converted to the value-added formylation product in the atmosphere, which far exceeds the porous MOC solid and nonporous PEG-imidazolium counterparts. This work offers a new method to prepare neat porous liquids for catalytic transformation of adsorbed gas molecules.

P-sulfonatocalix[8]arene and chitosan based vesicle formation studies by spectroscopic and thermal methods

p-sulfonatocalix [8]arene and chitosan based supramolecular amphiphilic vesicles were formed by electrostatic interaction between anionic character of calixarene and cationic chitosan molecules. UV–visible, fluorescence, dynamic light scattering and thermogravimetric analysis were performed for the characterization of p-SCX8 with chitosan. Increase in absorption and enhancement of fluorescence emission intensity attributed to vesicle formation between both calixarene and chitosan in aqueous media. Results obtained from size distribution curve of dynamic light scattering experiment gives clear evidence for vesicle formation at pH 4.98. Positive zeta potential values obtained from dynamic light scattering experiment gives the evidence for vesicle formation. Thermogravimetric analysis gives quantitative results for purity and stability of the vesicles. From overall studies we can conclude that degree of deacetylation as well as pH 4.98 of the solutions and anionic nature of pSCX8 plays important role in electrostatic interaction of vesicle formation.

Fluorescent Calixarene-Schiff as a Nanovehicle with Biomedical Purposes

Gene therapy is a technique that is currently under expansion and development. Recent advances in genetic medicine have paved the way for a broader range of therapies and laid the groundwork for next-generation technologies. A terminally substituted difluorene-diester Schiff Base calix[4]arene has been studied in this work as possible nanovector to be used in gene therapy. Changes to luminescent behavior of the calixarene macrocycle are reported in the presence of ct-DNA. The calixarene macrocycle interacts with calf thymus DNA (ct-DNA), generating changes in its conformation. Partial double-strand denaturation is induced at low concentrations of the calixarene, resulting in compaction of the ct-DNA. However, interaction between calixarene molecules themselves takes place at high calixarene concentrations, favoring the decompaction of the polynucleotide. Based on cytotoxicity studies, the calixarene macrocycle investigated has the potential to be used as a nanovehicle and improve the therapeutic efficacy of pharmacological agents against tumors.

DFT study of conformation, hydrogen bonds, IR, and Raman spectra of the sodium salt of p-hexasulfonatocalix[6]arene DFT

• The FTIR and FT Raman spectra of p -hexasulfonatocalix[6]arene hexasodium salt were studied. • The structural optimization and normal mode analysis were performed for p -hexasulfonatocalix[6]arene hexasodium salt. • The IR and Raman spectra of p -hexasulfonatocalix[6]arene hexasodium salt were calculated and interpreted. The vibrational spectra of p -hexasulfonatocalix[6]arene hexasodium salt ( SC6 ) and p ‑ tert -butylcalix[6]arene ( TB6 ) were studied. The comparison of the IR spectra SC6 and TB6 allows to distinguish bands of tert ‑butyl and sulfonate groups. The structure and the vibrational spectra of the SC6 molecule were calculated for the conformations of the compressed cone and the double partial cone . For the molecule SC6 , the conformation of a compressed cone is the most stable, and the conformation of a double partial cone is 43.6 Kcal/mol less stable. When replacing tert ‑butyl groups with sulfonatel groups, the cavity size of calixarene molecules increases from 5.22 ( TB6 ) to 7.80 Ǻ ( SC6 ). In the sodium salt of the SC6 molecule, six sodium ions are coordinated with the oxygen atoms of the sulfonate groups. Under the influence of sodium ions, the electron density is redistributed in the SC6 molecule, and its supramolecular properties change. The transition from TB6 to SC6 increases the ionization energy, electronic affinity, chemical potential and dipole moment. In the SC6 molecule, the frontal orbitals are located on aromatic and sulfonate groups. Due to these orbitals, calixarenes interact with biological objects. Optimized geometry and atom numbering for SC6 in the conformation compressed cone .

Calixarene molecule as an effective inhibitor of copper corrosion in 2.0 M H3PO4 and 0.5 M H2SO4 solutions

Calixarene molecule as an effective inhibitor of copper corrosion in 2.0 M H3PO4 and 0.5 M H2SO4 solutions

Comparative study of the vibrational spectra of carboxylate azocalix[4]arenes and azothiacalix[4]arenes

The vibrational spectra of calix[4]arene (p-CAC) and thiacalix[4]arenes with azobenzene units having carboxylate groups in the para (p-CATC) and meta position (m-CATC) were recorded and analyzed.The calculated structures of molecules p-CAC, p-CATC, and m-CATC are consistent with experimental X-ray data. The most stable and polar is the cone conformation with four intramolecular cooperative hydrogen bonds. In classical calixarenes, the hydrogen bonds are shorter and, therefore, more durable than in thiacalixarenes. The cone conformation retains for all the studied calixarene molecules. The energy differences between E- and Z-forms of azobenzene groups in p-CAC, p-CATC, and m-CATC are 254.4, 260.2, and 249.4 kJ/mol, respectively. The shape of the molecules changes noticeably upon isomerization of azobenzene groups.Upon passing from thiacalixarenes to classical calixarenes, the dipole moment of the molecule increases. The polarity of calixarene molecules changes upon isomerization of azobenzene units. Ionization energy electron affinity and electrophilicity are higher in classical calixarenes compared to thiacalixarenes. There are active sites of reaction and interaction in the narrow and wide rims of the calixarene molecules. Carboxylate groups are most active in the formation of complexes with metals.

Capture and Release Recyclable Dimethylaminomethyl-Calixarene Functional Cloths for Point-of-Use Removal of Highly Toxic Chromium Water Pollutants.

Chromium(VI) contamination of drinking water arises from industrial activity wherever there is a lack of environmental legislation enforcement regarding the removal of such pollutants. Although it is possible to remove such harmful metal ions from drinking water through large-scale facilities, there currently exists no safe and simple way to filter chromium(VI) oxoanions at the point of use (which is potentially safer and necessary in remote locations or humanitarian scenarios). High-surface-area cloth substrates have been functionalized with calixarene molecules for the selective capture of aqueous chromium(VI) oxoanions in the presence of structurally similar anions. This is accomplished by pulsed plasmachemical deposition of a linker layer and subsequent functionalization with dimethylaminomethyl-calixarene (5,11,17,23-tetrakis[(dimethylamino)methyl]-25,26,27,28-tetrahydroxycalix[4]arene). Chromium(VI) oxoanions are captured by simply passing polluted water through the functionalized cloth, while other ions not harmful/beneficial to human health remain in the water. These cloth filters are simple to use, highly selective, and easily recyclable-thus making them attractive for point-of-use application in geographic regions lacking appropriate wastewater treatment plants or flawed environmental monitoring systems. Chromium(VI) pollutants have been successfully removed from real-world contaminated industrial wastewater streams using the dimethylaminomethyl-calixarene functionalized cloths.

Electrochemical aspects of cyclodextrin, calixarene and cucurbituril inclusion complexes

The electrochemical behaviour of the host–guest complexes formed by cyclodextrin, calixarene and cucurbiturils host molecules with simple organic guest molecules and their applications using electrochemical studies are discussed in detail in this review. The change in the redox behaviour of the individual molecules upon complexation and the unique properties of the complexes formed are elaborated. The methodology and various electrochemical techniques used for the investigation of these host–guest are categorised with respect to the analytical methods. The electrochemical behaviour upon binding of host with guest and their applications are analysed in detail. The applications are ranging from simple molecular detection to sensing of toxicants, pollutants and biomolecules. The identification of cancer cells and discrimination of chiral molecules are the noteworthy application of these supramolecular electrochemical sensing systems. The aspects discussed in this review could help to extend the electrochemical applications of host–guest systems to utilize them in the highly important applications like cancer detection and pollutant detection.

Novel integrated sensing system of calixarene and rhodamine molecules for selective colorimetric and fluorometric detection of Hg2+ ions in living cells.

Three novel and facile calixarene derivatives (5, 6 and 7), which were appended with four rhodamine units at the upper rim of calixarene skeleton, were firstly prepared and evaluated for selective detection of metal ions in solution. Receptors (5) and (7) indicated immediate turn on fluorescence output toward Hg2+ ions over other most competitive metal ions with the ultralow detection limits, indicating their high efficiency and reliability. The binding response to Hg2+ ions in solution was also observed through a chromogenic change (from colorless to pale pink). Furthermore, in vitro and bio-imaging studies with MCF-7 or MIA PaCa-2 cell lines were also performed to investigate the use of receptors in biological systems in order to monitor of mercury ions. Results showed that new receptors (5) or (7) were cell permeable and suitable for real-time imaging of Hg2+ in living cells (MCF-7) or (MIA PaCa-2) without any damage to healthy cell lines (HEK 293).

Study of p-(3-carboxy-1-adamantyl)-calix[4]arene with hydrogen bonds along the upper and lower rim by IR spectroscopy and DFT.

The IR spectra of p-(3-carboxy-1-adamantyl)-calix[4]arene (AdC4A) were studied. Using IR spectroscopy, it has been shown that in calixarene in dilute solution in CCl4, there was no free hydroxyl absorption band. The hydroxyl group band was characterized by a very low frequency, which indicates a strong intramolecular hydrogen bond on the lower rim of the calixarene molecules. On the upper rim of the calixarene, the carboxyl groups form cyclic dimer or tetramer complexes via intermolecular hydrogen bonds. The cone conformation persists, but there is a mutual influence of the hydrogen bonds along the top and bottom rims of the calixarene molecule. The structure with dimeric hydrogen bonds between the carboxyl groups is 16.5KJ/mol more preferable than the structure with tetrameric cyclic hydrogen bonds for AdC4A. The reactivity depends on the type of association on the upper rim, whether these are hydrogen-bonded dimers or cyclic tetrameric association. Graphical abstract .

Host-Guest Complexation of Amphiphilic Molecules at the Air-Water Interface Prevents Oxidation by Hydroxyl Radicals and Singlet Oxygen.

The oxidation of antioxidants by oxidizers imposes great challenges to both living organisms and the food industry. Here we show that the host-guest complexation of the carefully designed, positively charged, amphiphilic guanidinocalix[5]arene pentadodecyl ether (GC5A-12C) and negatively charged oleic acid (OA), a well-known cell membrane antioxidant, prevents the oxidation of the complex monolayers at the air-water interface from two potent oxidizers hydroxyl radicals (OH) and singlet delta oxygen (SDO). OH is generated from the gas phase and attacks from the top of the monolayer, while SDO is generated inside the monolayer and attacks amphiphiles from a lateral direction. Field-induced droplet ionization mass spectrometry results have demonstrated that the host-guest complexation achieves steric shielding and prevents both types of oxidation as a result of the tight and "sleeved in" physical arrangement, rather than the chemical reactivity, of the complexes.

Investigation of hydrogen bonding in p-sulfonatocalix[4]arene and its thermal stability by vibrational spectroscopy

The vibrational spectra of p-sulfonatocalix [4] arene were studied. The geometrical parameters, the energies, the frequencies and the intensities of the bands in the IR and Raman spectra are calculated for four conformations. The most stable conformation of the p-sulfonatocalix[4]arene is the cone due to the cooperative cyclic intramolecular hydrogen bonding system. The strength of the hydrogen bonds depends on the type of substituent on the upper rim of the calixarene molecules. We studied the process of destruction of calixarenes using IR spectroscopy and TGA methods. Characteristic bands for each conformation were selected. HOMO covers aromatic units with notable conjugation, and LUMO belongs to sulfonate groups.

Calixarene-immobilized monolithic cryogels for preparative protein chromatography

New cation exchanger monolithic stationary phases were prepared by immobilization of three different calixarene derivatives (i.e. tetracarboxylate calix[4]arene, CLX-COO, tetrasulfonate calix[4]arene, CLX-SO3, and tetraphosphonate calix[4]arene, CLX-PO4) onto a monolithic cryogel support (i.e. poly(2-hydroksyethylmethacrilate-co-glycidyl methacrylate, P) and investigated with respect to preparative protein chromatography. The obtained monoliths were characterized through various techniques such as FTIR spectroscopy, isoelectric point measurements, titrimetric analyses, and mercury intrusion porosimetry. Protein retention was investigated using some model proteins (i.e. lysozyme, cytochrome c, and ɑ-chymotrypsinogen A, human serum albumin, and myoglobin), and the role of modifier (i.e. NaCl) concentration and pH was thoroughly analyzed under isocratic and gradient elution conditions. Overloading experiments were also conducted to study dynamic adsorption capacity and the obtained values were found to be ranging between 3 and 8 mg/mL depending on the type of calixarene molecule. Hence, higher or comparable protein adsorption capacities were seen to be applicable on calixarene-immobilized cryogels when compared to any other functionalized cryogels in the literature. Combined with the favorable properties of these monoliths, with respect to mass transport of large molecules, these results qualify calixarene functionalized monolithic cryogels as promising stationary phases for protein preparative purification.

Crystal structure of a supra-molecular lithium complex of p-tert-butyl-calix[4]arene.

Crystals of a supra-molecular lithium complex with a calix[4]arene derivative, namely tetra-methano-llithium 5,11,17,23-tetra-tert-butyl-25,26,27-trihy-droxy-28-oxidocalix[4]arene methanol monosolvate, [Li(CH3OH)4](C44H55O4)·CH3OH or [Li(CH3OH)4]+·(calix[4]arene-)]·CH3OH (where calix[4]arene- represents a mono-anion species because of deprotonation of one H atom of the calixarene hy-droxy groups), were obtained from p-tert-butyl-calix[4]arene reacted with LiH in tetra-hydro-furan, followed by recrystallization from methanol. The asymmetric unit comprises one mono-anionic calixarene mol-ecule, one Li+ cation coordinated to four methanol mol-ecules, and one methanol mol-ecule included in the calixarene cavity. The calixarene mol-ecule maintains a cone conformation by intra-molecular hydrogen bonding between one phenoxide (-O-) and three pendent calixarene hy-droxy groups (-OH). The coordinated methanol mol-ecules around the metal cation play a significant role in forming the supra-molecular assembly. The crystal structure of this assembly is stabilized by three sets of inter-molecular inter-actions: (i) hydrogen bonds involving the -OH and -O- moieties of the calixarene mol-ecules, the -OH groups of the coordinated methanol mol-ecules, and the -OH group of the methanol mol-ecule included in the calixarene cavity; (ii) C-H⋯π inter-actions between the calixarene mol-ecules and/or the coordinated methanol mol-ecules; (iii) O-H⋯π inter-actions between the calixarene mol-ecule and the included methanol mol-ecule.

FT-IR and FT-Raman study of hydrogen bonding in p-alkylcalix[8]arenes

The FTIR and FT Raman spectra of p-alkylcalix[8]arenes (alkyl = tert-butyl, isononyl) were recorded. Analysis of IR spectra showed that the cyclic cooperative intramolecular hydrogen bond is realized in calix[8]arene. It was found that the strength of the cyclic cooperative intramolecular hydrogen bond in the series of alkyl derivatives of calix[8]arenes depends very little on the replacement of the p-tert-butyl groups by the more bulky isononyl group. From our data follows that the orientation of aromatic fragments in calixarene molecules depends on the type of alkyl substituent.An analysis of the changes in the IR spectra with heating and dissolution shows that the conformation of the “pleated-loop” is retained in p-tert-butylcalix[8]arene. It turned out that the intramolecular hydrogen bond is a “probe” of the conformation of calixarene molecules and IR spectroscopy is a unique method that allows one to follow the slightest nuances of changes in the H-bound system of these supermolecules.

Electrospinning of novel calixarene-functionalized PAN and PMMA nanofibers: Comparison of fluorescent protein adsorption performance

This present paper is the first report showing the preparation and protein binding properties of new polyacrylonitrile (PAN) and/or Poly(methyl methacrylate) (PMMA) nanofibers based calixarene tetraester units by electrospinning of calixarene tetraester and PAN or PMMA solutions in DMF. The newly prepared nanofibers materials was fully characterized by using spectroscopic techniques. From the obtained spectroscopic results, existing of calixarene molecules onto the fiber matrix was proved by the presence of the characteristic calixarene bands in FTIR spectra and considerable changing of surface morphologies of fiber matrix in SEM image. Furthermore, the protein extraction studies were performed by batch method toward green fluorescence protein (GFP) as a model protein and protein binding results exhibited that nanofibers based calixarene could be actively used as a support material for the binding of green fluorescence protein (GFP) from aqueous solutions. The results were compared with bare PAN and PMMA without calixarene and it was observed that GFP binding was higher in the case of calixarene-coated nanofibers especially for nanofibers containing calixarene ester derivatives. In addition, amino acid extraction studies were also performed to clarify the possible binding interaction between nanofibers and protein. From the amino acid extraction experiments, it was determined that the excellent interaction between protein and nanofibers became with amino acids having aromatic side arms such as phenylalanine and tryptophan.

Electrospun Nanofibrous Polyacrylonitrile/calixarene Mats: an Excellent Adsorbent for the Removal of Chromate Ions from Aqueous Solutions.

Herein, calixarene molecules containing piperidine units at lower rim or upper rim of calix skeleton was turned into a water resistant composite nanofiber adsorbent using polyacrylonitrile (PAN) polymeric support via electrospinning process. The PAN based calixarene nanofibrous adsorbents showed an excellent adsorption capacity toward the toxic chromate anions in aqueous solution. Furthermore, this new nanofiber mats would be promising filter materials for drinking water purification.

Electronic structure of functionalized thia- and calix[4]arenes

The electronic structure of calix[4]arene phosphine oxides (CPO) and thiacalix[4]arene phosphine oxides (TCPO) is studied by X-ray photoelectron and emission spectroscopy and quantum chemical methods. The electron density distribution over atoms contained in CPO and TCPO is analyzed. The structure of higher occupied molecular orbitals (HOMO) is examined. It is shown that HOMOs of these compounds mainly consist of contributions of oxygen 2p atomic orbitals (AOs) of phosphoryl and hydroxyl moieties and also bridging sulfur 3p AOs, which indicates the bifunctionality of the considered extractant molecules. The mutual effect of the lower and upper rims of CPOs and TCPOs as well as the effect of their structures on the electron density distribution over calixarene molecules is investigated.

Compared in vivo efficiency of nanoemulsions unloaded and loaded with calixarene and soapy water in the treatment of superficial wounds contaminated by uranium

No emergency decontamination treatment is currently available in the case of radiological skin contamination by uranium compounds. First responders in the workplace or during an industrial nuclear accident must be able to treat internal contamination through skin. For this purpose, a calixarene nanoemulsion was developed for the treatment of intact skin or superficial wounds contaminated by uranium, and the decontamination efficiency of this nanoemulsion was investigated in vitro and ex vivo. The present work addresses the in vivo decontamination efficiency of this nanoemulsion, using a rat model. This efficiency is compared to the radio-decontaminant soapy water currently used in France (Trait rouge®) in the workplace. The results showed that both calixarene-loaded nanoemulsion and non-loaded nanoemulsion allowed a significant decontamination efficiency compared to the treatment with soapy water. Early application of the nanoemulsions on contaminated excoriated rat skin allowed decreasing the uranium content by around 85% in femurs, 95% in kidneys and 93% in urines. For skin wounded by microneedles, mimicking wounds by microstings, nanoemulsions allowed approximately a 94% decrease in the uranium retention in kidneys. However, specific chelation of uranium by calixarene molecules within the nanoemulsion was not statistically significant, probably because of the limited calixarene-to-uranium molar ratio in these experiment conditions. Moreover, these studies showed that the soapy water treatment potentiates the transcutaneous passage of uranium, thus making it bioavailable, in particular when the skin is superficially wounded.