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Inherently chiral calixarenes have garnered significant attention due to their distinctive properties, yet the development of efficient catalytic asymmetric synthesis methods remains a critical challenge. Herein, we report the asymmetric synthesis of calix[4]arenes featuring inherent or both inherent and axial chirality via a cobalt‐catalyzed C−H activation/annulation strategy in high yield with excellent enantio‐ and diastereoselectivity (up to >99 % ee and >20 : 1 dr). Electrooxidation was also suitable for this transformation to obviate the sacrificial metal oxidants, underscoring the environmentally friendly potential of this approach. A key octahedral cobaltacycle intermediate was synthesized and characterized, providing valuable insights into the mode of enantio‐ and diastereocontrol of this protocol. Noteworthy photoluminescence quantum yields of up to 0.94 were measured, underscoring the potential of these compounds in the domain of organic fluorescent materials. [ABSTRACT FROM AUTHOR]

We have synthesized a new ion pair receptor (2) consisting of a cone‐calix[4]arene bearing a combination of ethyl esters and ethers as a cation binding site and a calix[4]pyrrole subunit acting as an anion binding site. Ion pair receptor 2 complexes LiCl, NaCl, and CsCl among alkali metal chloride salts with distinct complexation modes and affinities in 10 % methanol‐d4 in chloroform‐d. For instance, relatively small Li+ and Na+ cations are bound to the oxygen atoms of the functionalized calix[4]arene lower rim with Cl− being hydrogen bonded to the calix[4]pyrrole NHs while the larger Cs+ cation is bound to the cone‐shaped calix[4]pyrrole cavity via a π‐cation interaction. By contrast, in the co‐presence of all MCl salts (M=Li, Na, K, Rb, and Cs), receptor 2 binds LiCl with complete selectivity. Besides, receptor 2 is capable of extracting LiCl selectively into a chloroform or a dichloromethane organic phase from its solid source containing all other MCl salts. [ABSTRACT FROM AUTHOR]

Herein, the presented results show that previously studied DNA/RNA-interacting bis-imidazole-calix[4]arene systems can, in aqueous solutions, efficiently bind a series of biorelevant transition metal cations by coordination with the two imidazole arms at the small rim of their macrocyclic basket. The SCXRD and NMR results structurally characterised the complexes formed by referent bis-imidazole-calix[4]arene with Cu2+ and Zn2+. In solid-state (crystal), the bis-anilino derivative/Cu2+ complex, only upon exposure to the air, undergoes intramolecular dehydrogenative coupling of two neighbouring aniline units, yielding an azo bridge at the large rim of the calix[4]arene basket. In the biorelevant aqueous solution, the comparison of fluorometric titrations of referent calix[4]arene, with its analogues having one or two pyrene units grafted at the opposite (large) rim, revealed moderate-to-strong affinity towards transition metal cations, and, more importantly, a strong impact of pyrene on the binding affinity towards some cations. The pyrene arm(s) significantly diminished the affinity of the calix[4]arene-imidazole ligand towards Cu+ and strongly increased the affinity towards divalent Co2+ and Cd2+ cations. Moreover, the fluorometric response of some studied derivatives was strappingly sensitive to cation type. Since the counter-anion plays only a marginal role, such a change in selectivity is attributed to the intramolecular interaction of pyrene(s) with the calix[4]arene-imidazole system, sterically controlling the metal cation binding site. [ABSTRACT FROM AUTHOR]

In order to deeply understand calix[4]arene bridge mononitration, four representative tetrasubstituted p‐tert‐butylcalix[4]arenes were selected as substrates to theoretically explore calix[4]arene structural effects. Based on our proposed mechanism, the four corresponding calix[4]arene bridge radicals were artificially constructed. Then, three different levels of density functional theory (DFT) were used to calculate their pertinent species energies in radical generations and radical spin densities. The nitration differences of these four substrates were tentatively interpreted through comparison of their reaction activation energies in radical generations and radical stability. As a result, Gibbs activation free energies in radical generations cannot rationally interpret their nitration behaviors while radical stability can, which are characterized with radical stability energies (RSEs) and center carbon spin densities (SDcs). From radical structural analysis, it can be concluded that aromatic ring inversion is remarkably beneficial to enhance calix[4]arene bridge radical stability through strengthening spin delocalization onto their connecting aromatic rings, whereas a substituent with large steric hindrance is unbeneficial due to weakening spin delocalization. The theoretical analysis of radical intrinsic structural effects on their spin delocalizations provides guidance in designing new efficient calix[4]arene‐based substrates. [ABSTRACT FROM AUTHOR]

The solvothermal reaction of FeCl2 ⋅ 4H2O and H4TBC[4] in a basic dmf/EtOH solution affords an [FeIII18] Keplerate conforming to a stellated cuboctahedron. Magnetic and heat capacity measurements reveal spin frustration effects arising from the high symmetry. A crossover between inverse and direct magnetocaloric effects is observed at ~10 K for applied‐field changes lower than 3 T. [ABSTRACT FROM AUTHOR]

The solvothermal reaction of FeCl2 ⋅ 4H2O and H4TBC[4] in a basic dmf/EtOH solution affords an [FeIII18] Keplerate conforming to a stellated cuboctahedron. Magnetic and heat capacity measurements reveal spin frustration effects arising from the high symmetry. A crossover between inverse and direct magnetocaloric effects is observed at ~10 K for applied‐field changes lower than 3 T. [ABSTRACT FROM AUTHOR]

The solvothermal reaction of FeCl2 ⋅ 4H2O and H4TBC[4] in a basic dmf/EtOH solution affords an [FeIII18] Keplerate conforming to a stellated cuboctahedron. Magnetic and heat capacity measurements reveal spin frustration effects arising from the high symmetry. A crossover between inverse and direct magnetocaloric effects is observed at ~10 K for applied‐field changes lower than 3 T. [ABSTRACT FROM AUTHOR]

The solvothermal reaction of FeCl2 ⋅ 4H2O and H4TBC[4] in a basic dmf/EtOH solution affords an [FeIII18] Keplerate conforming to a stellated cuboctahedron. Magnetic and heat capacity measurements reveal spin frustration effects arising from the high symmetry. A crossover between inverse and direct magnetocaloric effects is observed at ~10 K for applied‐field changes lower than 3 T. [ABSTRACT FROM AUTHOR]

In this study, p-morpholinomethylcalix[4]arene (p-MC4) was synthesized using Mannich reaction and utilized for the fabrication of polyacrylonitrile nanofibers impregnated with p-morpholinomethylcalix[4]arene (PAN/p-MC4) using electrospinning. The nanofibers were prepared by blending 12% solution of PAN with 20% solution of p-MC4. The PAN/p-MC4 NFs were thoroughly evaluated for their removal efficiency of Cu2+ from the aqueous media. The selectivity of PAN/-p-MC4 nanofibers was also examined by adsorbing a set of metal ions with same charge and similar ionic radius. The results of distribution ratio showed that PAN/p-MC4 nanofibers have superior selectivity for Cu2+ as compared to other heavy metal ions. The relative selectivity coefficients of PAN/p-MC4 nanofibers were found to be 25.2, 14.1, 8.9, and 4.03 for Cu2+/Ni2+, Cu2+/Co2+, Cu2+/Cd2+ and Cu2+/Pb2+, respectively. This indicates that PAN/p-MC4 nanofibers have a higher selectivity for Cu2+ ions. Numerous parameters such as pH, time, adsorbent dosage and analyte concentration were optimized to evaluate the maximum adsorption capacity of nanofibers for Cu2+. Adsorption isotherm models showed that the adsorption is promising and follows Langmuir adsorption isotherm. Whereas, PAN/p-MC4 nanofibers followed pseudo- second order kinetics during adsorption experiments. The PAN/p-MC4 nanofibers showed excellent adsorption capacity (qo) of 65.35 mg/g for Cu2+ at pH 5 in 60 min under shaking speed of 120 rpm. Moreover, PAN/p-MC4 nanofibers had been used to remove Cu2+ from real surface water samples. According to the results, PAN/p-MC4 nanofibers are more effective adsorbent for removing Cu2+ from contaminated water. [ABSTRACT FROM AUTHOR]

The calixarenes, 5,17-dibromo-26,28-dihydroxy-25,27-dipropynyloxycalix[4]arene (C34H26Br2O4, 1), 5,17-dibromo-26,28-dipropoxy-25,27-dipropynyloxycalix[4]arene (C40H38Br2O4, 2) and 25,27-bis(2-azidoethoxy)-5,17-dibromo-26,28-dihydroxycalix[4]arene (C32H28Br2N6O4, 3) possess a pinched cone molecular shape for 1 and 3, and a 1,3-alternate shape for compound 2. In calixarenes 1 and 3, the cone conformations are additionally stabilized by intramolecular O—H...O hydrogen bonds, while in calixarene 2 intramolecular Br...Br interactions consolidate the 1,3-alternate molecular conformation. The dense crystal packing of the cone dialkyne 1 is a consequence of π–π, C—H...π and C—H...O interactions. In the crystal of the diazide 3, there are large channels extending parallel to the c axis, which are filled by highly disordered CH2Cl2 solvent molecules. Their contribution to the intensity data was removed by the SQUEEZE procedure that showed an accessible void volume of 585 Å3 where there is room for 4.5 CH2Cl2 solvent molecules per unit cell. Rigid molecules of the 1,3-alternate calixarene 2 form a columnar head-to-tail packing parallel to [010] via van der Waals interactions, and the resulting columns are held together by weak C—H...π contacts.

Trialkyl-monoacetic acid derivatives of p–t-octylcalix[4]arene and calix[4]arene were prepared to investigate the effect of the alkyl branches attached to the phenoxy oxygen atoms and the p-position on the selective extraction of Li+ over Na+. Alkyl branches on the phenoxy oxygen atoms remarkably affected the Li+ selectivity, whereas those at the p-position had less effect. The former can contribute to excluding Na+ extraction while enabling Li+ extraction. Optimal selection of the alkyl branch improves the Li+ selectivity of calix[4]arene. However, sterically-hindered p–t-octylcalix[4]arene with three 2-ethylbutyl branches exhibited opposite selectivity. [ABSTRACT FROM AUTHOR]

The calixarenes, 5,17-di­bromo-26,28-dihy­droxy-25,27-dipropynyloxycalix[4]arene (C34H26Br2O4, 1), 5,17-di­bromo-26,28-dipropoxy-25,27-dipropynyloxycalix[4]arene (C40H38Br2O4, 2) and 25,27-bis­(2-azido­eth­oxy)-5,17-di­bromo-26,28-di­hydroxy­calix[4]arene (C32H28Br2N6O4, 3) possess a pinched cone mol­ecular shape for 1 and 3, and a 1,3-alternate shape for compound 2. In calixarenes 1 and 3, the cone conformations are additionally stabilized by intra­molecular O—H⋯O hydrogen bonds, while in calixarene 2 intra­molecular Br⋯Br inter­actions consolidate the 1,3-alternate mol­ecular conformation. The dense crystal packing of the cone dialkyne 1 is a consequence of π–π, C—H⋯π and C—H⋯O inter­actions. In the crystal of the diazide 3, there are large channels extending parallel to the c axis, which are filled by highly disordered CH2Cl2 solvent mol­ecules. Their contribution to the intensity data was removed by the SQUEEZE procedure that showed an accessible void volume of 585 ų where there is room for 4.5 CH2Cl2 solvent mol­ecules per unit cell. Rigid mol­ecules of the 1,3-alternate calixarene 2 form a columnar head-to-tail packing parallel to [010] via van der Waals inter­actions, and the resulting columns are held together by weak C—H⋯π contacts. [ABSTRACT FROM AUTHOR]

In this study, gold-coated quartz tuning forks (QTFs) sensing devices functionalized with self-assembled monolayers (SAM) of a lower-rim functionalized calix[4]arene methoxy ester were used for the detection of divalent Ca2+ and Pb2+ ions in aqueous solutions by utilizing adsorption behavior and the radiative effect. The gold-coated QTF functionalized calix[4]arene methoxy ester sensing device was tested by measuring the respective frequency shifts obtained using small (60 µL) samples of aqueous PbCl2 at two different concentrations (10−6 and 10−4 M). For 10−4 M solutions of PbCl2, results showed that the resonance frequency shift Δf = 317 Hz, from 32,867 Hz (fCalix) to 32,550 Hz (fCalix⊃Pb2+) due to the absorption of lead (Pb2+) ions (10-4 M) by calixl[4]arene methoxy ester receptor molecules on the QTF sensing layer from the aqueous solution to forming the ([Calix ⊃ Pb2+]) complex. The most significant frequency changes were observed at a concentration of 10−6 M CaCl2, where CaCl2 exhibited the biggest change of 356 Hz, from 32,893 Hz (fCalix) to 32,537 Hz (fCalix⊃Ca2+), compared to 317 Hz for PbCl2 (10−4 M). The limit of detection was 100 femtomolar (fM) for CaCl2 and 245 fM for PbCl2. After that, we irradiated the receptor molecules which was holding Pb2+ ions in the complex ([calix ⊃ Pb2+]) on the QTF sensing layer with a radiation dose ranging from 7.5 to 50 µGy of gamma rays from the Cesium-137 source for 30 min. Interestingly, it was observed that the resonance frequency shift (Δf = 54 Hz) back to 32,604 Hz from 32,550 Hz (f(Calix⊃Pb2+)), which strongly suggests that the Pb2+ ion removed from ([calix ⊃ Pb2+]) complex on the QTF sensing layer due to gamma radiation dose. To follow up on the radiation effect of the ([calix ⊃ Pb2+]) on the QTF sensing layer, we stopped the gamma radiation source and kept it for an additional 10 min to see if there was any resonance frequency. It was noticed that an additional resonance frequency shifted (Δf = 33 Hz) back to 32,637 Hz from 32,604 Hz after stopping the gamma radiation source for 10 min. We assume that the complex ([calix ⊃ Pb2+]) absorbs the gamma radiation and continues the removal of Pb2+ ions from the complex on the sensing layer. A similar phenomenon was also observed for the absorption of lead (Pb2+) ions (10-6 M) by calix[4]arene methoxy ester receptor molecules on the QTF sensing layer from the aqueous solution to forming the ([Calix ⊃ Pb2+]) complex. The resonance frequency shift Δf = 142 Hz, from 32,706 Hz (fCalix) to 32,564 Hz (fCalix⊃Pb2+) due to the absorption of lead (Pb2+) ions (10-6 M) by calix[4]arene methoxy ester receptor molecules on the QTF sensing layer from the aqueous solution to forming the ([Calix ⊃ Pb2+]) complex. Subsequent exposure to gamma radiation, with doses ranging from 7.5 to 50 µGy from a Cesium-137 source over 30 min, prompted a resonance frequency shift (Δf = 37 Hz) back to 32,606 Hz from 32,564 Hz (f(Calix⊃Pb2+)). This shift strongly suggests the removal of Pb2+ ions from the ([calix ⊃ Pb2+]) complex on the QTF sensing layer due to gamma radiation dose. X-ray photoelectron spectroscopy (XPS) analysis confirmed the chemical adsorption of Pb2+ ions onto the gold-coated QTFs functionalized calix[4]arene adsorbent sensing layer surface. Therefore, the technology underlying the calix[4]arene-functionalized sensing device holds promise for diverse industrial applications, supporting potential advancements in water pollution mitigation through the proposed adsorption and irradiation mechanism.

We have developed a chemosensor using calix[4]arene, which features a thiosemicarbazone binding/sensing unit and a naphthalene chromogenic group. Our objective was to understand the intricate binding affinity of these chemosensors towards a diverse range of anions and cations using UV–Visible, HNMR and IR spectroscopic techniques. We showed that this chemosensor can form complexes with Ag(I) or Cu (II) and to detect CN− or F− ions by deprotonation of thiosemicarbazone. To understand the behavior of these interactions, our analysis provides information on the interaction patterns between the receptors and the ions. The sulfur and imine nitrogen on the thiosemicarbazone substituent are vital sites of engagement for cation ions, as evidenced by the observed changes in IR. HNMR studies for interaction with anions indicate the involvement of the thiosemicarbazone hydrogens. Interactions taking place during complex formation with cations lead to changes in the color of the solution or solid complex, easy to follow by UV–Vis spectrocopy. Our study improves the understanding of molecular recognition of this chemosensor, highlighting its potential for ion- selective detection. [ABSTRACT FROM AUTHOR]

New macrocyclic Schiff bases, lower rim disubstituted imine derivatives of thia- and calix[4]arenes 7 and 8 adopted in a cone stereoisomeric conformation, bearing two tert-butyl substituents grafted to iminophenol coordinating sites, and containing a spacer composed of two methylene bridges were synthesized. The prepared compounds were characterized by a complex of physicochemical methods in solution (1H/13C NMR spectroscopy, MALDI TOF mass spectrometry) and in the crystalline phase (IR spectroscopy, single-crystal X-ray diffraction (XRD)). In crystals calix[4]arene 7 forms a solvate in which acetonitrile or methanol molecules are included into the macrocycle cavity, whereas the crystals of thiacalix[4]arene 8 contain no solvent molecules. The difference in the conformational behavior of the macrocyclic platform was evidenced when comparing the crystal structures of calix[4]arene 7 and thiacalix[4]arene 8. The stoichiometry and the logarithm and stability constant values of the corresponding complexes of the synthesized macrocyclic Schiff bases with 3d-metal cations (CoII, NiII) in solution were determined using spectrophotometry titration. When interacting with CoII cations, compound 7 forms complexes with stoichiometry Lig: M = 1: 1 and 1: 2 (Lig is ligand, and M is metal). In the case of compound 8, complexes with the stoichiometry Lig: M = 1: 4, as well as 1: 2, are observed, which presumably indicates the involvement of "soft" sulfur atoms in the interaction with the metal cations. The replacement of CoII cations by NiII resulted in the formation in the solution of complexes with the stoichiometry Lig: M = 2: 1, 1: 1 and Lig: M = 1: 1, 1: 2 for compounds 7 and 8, respectively. [ABSTRACT FROM AUTHOR]

A convenient protocol for the synthesis of 25,26,27-tribenzoyl-28-[((S)-1-diphenylphos- phanyl-propan-2-yl)oxy]-calix[4]arene via stereospecific methylation on Evans' oxazolidinone moiety was reported. According to the 13C NMR analysis of this phosphine, the calix[4]arene skeleton adopted a 1,3-alternate conformation. The latter conformation of the macrocycle and the (S)-chirality of the carbon atom bearing the methyl substituent were confirmed by a single-crystal X-ray diffraction study. After coordination of the phosphinated ligand to the dimeric [RuCl2(p-cymene)]2 organometallic precursor, the resulting arene–ruthenium complex was tested in the asymmetric reduction of acetophenone and alcohol was obtained with modest enantiomeric excess. [ABSTRACT FROM AUTHOR]

The current work explores the antioxidant and antimicrobial activity of a newly synthesized calix[4] arene acetanilide derivative (3), which was synthesized through Mannich reaction by the treatment of calix[4] arene with acetanilide, formaldehyde and acetic acid in tetrahydrofuran, The antioxidant activity was determined by using DPPH method. Results show that the new synthesized compound 3 has good antioxidant activity. The antimicrobial activity of 3 was staunched against different types of microorganisms, i.e. gram-negative and gram-positive bacterial strains (Escherichia Coli ATCC 8739 and Staphylococcus Aureus ATCC 10231) along with a fungus (Aspergillus Niger ATCC 16405). A suitable agar medium (Mueller Hinton agar) was applied for the growth of microorganisms. Kirby-Bauer well agar diffusion method was used to check the antimicrobial activity. The bacterial strains zone has been observed in between 250–4000 µg/ml. It is noticed that compound 3 has very good effect against fungus A niger as compared to bacterial strains. Its minimum inhibitory concentration (MIC) against A. niger, S. aureus and E. coli is found to be 250, 500 and 1000 µg/mL, respectively. Consequently, the study has been compared with the reported calix[4] arene derivatives and it has been revealed that the compound 3 is a good antimicrobial agent. Hence, it could be inferred that compound 3 is considerably effective against selected microorganisms and may be used as a medicine in near future and beneficial for the human. [ABSTRACT FROM AUTHOR]

Aim. The goal of work is to study the effects of calix[4]arenes C-715 and C-772 on Ca2+-transport, the electron transport chain activity, and the reactive oxygen species generation in the mitochondria of rat uterine smooth muscle. Methods. Measurement of changes in NADH autofluorescence, as well as the energy-dependent accumulation of Ca2+ and reactive oxygen species generation in the fraction of isolated mitochondria was carried out using the spectrofluorimetry method. The hydrodynamic diameter of mitochondria was measured using the laser correlation spectroscopy method. Results. It was found that calix[4]arenes C-715 and C-772 moderately inhibit both the NADH oxidation and the energy-dependent Ca2+ accumulation by isolated mitochondria. We also showed that the studied calix[4]arenes, depending on concentration and time, reduce the level of reactive oxygen species generation by mitochondria. Additionally, it was revealed that the studied compounds moderately increase mitochondria hydrodynamic diameter depending on concentration. Conclusions. Studied calix[4]arenes slow down the oxidation of NADH in isolated mitochondria, which represents an inhibitory effect on the electron transport chain functioning, in particular its complex I. Since this might lower the electrochemical potential of the inner mitochondrial membrane, we observed reduce of energy-dependent Ca2+ accumulation. Selected compounds decrease the level of reactive oxygen species generation by isolated mitochondria, which could be considered as protective effect on organelles. A moderate increase in mitochondria hydrodynamic diameter suggests that the studied compounds do not cause mitochondrial dysfunction. Researched calix[4]arenes can be used in experimental practice to influence the mitochondrial functional activity.

New crystalline tetranuclear cluster is prepared by the interaction of manganese(II) chloride with calix[4]arene 3 functionalized at the upper rim by distal p-(4-nitrophenyl)diazenyl and p-tert-butyl groups displaying different electronic effects and sizes. The structure of the cluster is studied by single-crystal XRD. Due to the presence of (4-nitrophenyl)diazenyl moieties at the upper rim of the macrocyclic ligand, the molecules of the tetranuclear clusters are involved in π-stacking interactions leading to the formation of 2D supramolecular layers affording a porous crystal packing. [ABSTRACT FROM AUTHOR]

A light controllable two‐photon near‐infrared (NIR) optical probe is conveniently constructed by multivalent supramolecular co‐assembly of amphiphilic sulfonatocalix[4]arene (SC4A), tricationic triphenylamine (TPA), and diarylethene derivative (DE). The obtained results indicate that the formed SC4A/TPA nanoparticle displays assemble‐confined behaviors and enhances the two‐photon excited NIR emission. Benefiting from the reversible ring‐opened and closed behaviors of the DE under 365 and > 600 nm light irradiation, the dicationic DE in the assembly could act as an energy acceptor after 365 nm light irradiation, then the co‐assembly of SC4A/TPA/DE could achieve a NIR fluorescence ON and OFF switch and is successfully applied in HeLa cell imaging, providing a convenient approach to supramolecular two‐photon switch for cell imaging. [ABSTRACT FROM AUTHOR]

This study describes the removal of methyl orange (MO) and methyl red (MR) dyes from water samples using morpholinomethylcalix[4]arene immobilised silica (MIS) resin. The silica surface has been modified by p-morpholinomethylcalix[4]arene moiety and was characterised by FT-IR spectroscopy and SEM techniques. The adsorption capacity of MIS-resin was checked through batch adsorption experiments under the optimised conditions of pH, MIS-resin dose, time, and temperature. Results show that adsorption of MO and MR dyes are highly affected by the change in pH; thus, the higher adsorption percentages were achieved at pH 5.3 and 6.6 respectively. The adsorbent dosage has been optimised and it was noticed that the maximum adsorption was achieved by using 40 mg.L−1 of MIS-resin dose. The adsorption rate of dyes was investigated by applying the pseudo-first and second-order kinetic models and it has been observed that the experimental data shows a better correlation coefficient with the pseudo-second-order kinetic model. The feasibility of adsorption was analysed by thermodynamic parameters such as ∆H°, ∆G°, and ∆S° values indicate that the adsorption of dyes is exothermic and spontaneous. The equilibrium data have been validated using Langmuir and Freundlich models and the Langmuir model has a good correlation coefficient (R2 0.99). The MIS-resin was applied onto industrial effluents and it has been observed that the prepared resin is a very efficient adsorbent for the treatment of dyes contaminated wastewater. The adsorption of MO and MR dyes onto MIS-resin was well defined by computational chemical modelling at the B3LYP/LANL2DZ/6-311++G (d,p) level using G09W software. [ABSTRACT FROM AUTHOR]

An abrupt lengthening (from 295 to 684 μs) of the luminescence decay time of Tb3+ ions in a solution of a terbium(III) complex with tetra-1,3-diketone calix[4]arene in the region of the solution crystallization temperature (212 K) was observed. This fact testifies to the complex's sensitivity to the structure of the local environment, which can be used for spectroscopic purposes and remote monitoring of the phase state of the medium. [ABSTRACT FROM AUTHOR]

In this study, a composite film was developed for the electrochemical sensing of tryptophan (Trp). Porous reduced graphene oxide (PrGO) was utilized as the electron transfer layer, and a C-undecylcalix[4]resorcinarene Langmuir–Blodgett (CUCR-LB) film served as the molecular recognition layer. Atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy, scanning electron microscopy (SEM), and electrochemical experiments were employed to analyze the characteristics of the CUCR-LB/PrGO composite film. The electrochemical behavior of Trp on the CUCR-LB/PrGO composite film was investigated, revealing a Trp linear response range of 1.0 × 10−7 to 3.0 × 10−5 mol L−1 and a detection limit of 3.0 × 10−8 mol L−1. Furthermore, the developed electroanalytical method successfully determined Trp content in an amino acid injection sample. This study not only introduces a rapid and reliable electrochemical method for the determination of Trp but also presents a new strategy for constructing high-performance electrochemical sensing platforms. [ABSTRACT FROM AUTHOR]

Calix[4]arene/polyurethane (C4PU) has been synthesized and characterized as an alternative adsorbent for the adsorption of methylene blue (MB) and malachite green (MG) dyes from the aqueous solution. C4PU was synthesized by reacting p-tert-butyl calix[4]arene with hexamethylene diisocyanate (HMDI) as the cross-linking agent. Different polymer ratios were synthesized, and C4PU-4 shows better adsorption than other ratios. The polymer was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) analysis, and point of zero charges (pHPZC). The isotherms and kinetics of the adsorption of MB and MG were studied under a range of experimental conditions, including pH, adsorbent dosage, initial dye concentration, and contact time. The adsorption was determined by the adsorption percentage of MB and MG dyes from the solution. The Langmuir isotherm model best describes the adsorption process for both dyes, and it follows a pseudo-second-order kinetic model, with the maximum adsorption capacity (qmax) of MB and MG, respectively, was found to be 1.991 mg·g−1 and 2.240 mg·g−1. [ABSTRACT FROM AUTHOR]

Calixarenes are known as fascinated macromolecules due to their flexible structure that can be cast into different fields of application. These macromolecules have been used as quick and highly selective functional material for the extraction and separation of metal ions. This study explores metal ion removal efficiency of new calixarene coated silica resin from aqueous environment through solid phase extraction. The calixarene-coated silica resin (CCS resin) was synthesized and characterized by FTIR, SEM, XRD, EDS and BET. Static and dynamic adsorption experiments were followed to check the removal efficiency of CCS resin. Adsorption experiment shows that, CCS resin has strong potential for the removal of divalent and trivalent metal ions as compare to monovalent metal ions. Adsorption data have been evaluated by applying Langmuir, Freundlich, D-R models and Thomas dynamic adsorption models. The adsorption isotherm of the CCS resin agreed well with the Langmuir adsorption equation with regression coefficient of 0.99 and good monolayer adsorption capacities such as 3.22, 2.95, 3.04, 3.11, 2.81 and 2.82 (mol.g−1) for Hg2+ Pb2+ La3+ Cr3+ Al3+ and Fe3+ respectively. The D-R isotherm model suggests that the adsorption process follow ion exchange mechanism with mean sorption energy falls in the range of 9.0–16 KJ.mol−1. Moreover, the exhaustion capacity of column was calculated by using the Thomas model, which shows very small qo value with good fit to data (R2 =0.99). The thermodynamic and kinetic studies have also been performed, which reveals that the reaction is spontaneous and exothermic in nature and follows pseudo second-order kinetics. [ABSTRACT FROM AUTHOR]

Two novel fluorescent probes L1 and L2 for recognizing Al3+ have been prepared by cooperating salicylaldehyde‐derived Schiff base groups onto the upper rim of the calix[4]arene. Of these probes, L2 is the most effective at recognizing Al3+, displaying a highly selective fluorescence "on" response with an emission wavelength at 478 nm and a Stokes shift of 88 nm. Additionally, probe L2 can form a 1 : 1 coordination complex with Al3+ with a binding constant of 2.6×1010 M−1. Furthermore, its fluorescence intensity exhibits a good linear relationship with Al3+ concentration within the range of 2.0×10−5 M to 1.4×10−4 M, and the probe has a low detection limit of 4.36×10−7 M. [ABSTRACT FROM AUTHOR]

Quartz tuning forks (QTFs), which were coated with gold and with self-assembled monolayers (SAM) of a lower-rim functionalized calix[4]arene methoxy ester (CME), were used for the detection of benzene, toluene, and ethylbenzene in water samples. The QTF device was tested by measuring the respective frequency shifts obtained using small (100 µL) samples of aqueous benzene, toluene, and ethylbenzene at four different concentrations (10−12, 10−10, 10−8, and 10−6 M). The QTFs had lower limits of detection for all three aromatic hydrocarbons in the 10−14 M range, with the highest resonance frequency shifts (±5%) being shown for the corresponding 10−6 M solutions in the following order: benzene (199 Hz) > toluene (191 Hz) > ethylbenzene (149 Hz). The frequency shifts measured with the QTFs relative to that in deionized water were inversely proportional to the concentration/mass of the analytes. Insights into the effects of the alkyl groups of the aromatic hydrocarbons on the electronic interaction energies for their hypothetical 1:1 supramolecular host–guest binding with the CME sensing layer were obtained through density functional theory (DFT) calculations of the electronic interaction energies (ΔIEs) using B3LYP-D3/GenECP with a mixed basis set: LANL2DZ and 6-311++g(d,p), CAM-B3LYP/LANL2DZ, and PBE/LANL2DZ. The magnitudes of the ΔIEs were in the following order: [Au4-CME⊃[benzene] > [Au4-CME]⊃[toluene] > [Au4-CME]⊃[ethylbenzene]. The gas-phase BSSE-uncorrected ΔIE values for these complexes were higher, with values of −96.86, −87.80, and −79.33 kJ mol−1, respectively, and −86.39, −77.23, and −67.63 kJ mol−1, respectively, for the corresponding BSSE-corrected values using B3LYP-D3/GenECP with LANL2dZ and 6-311++g(d,p). The computational findings strongly support the experimental results, revealing the same trend in the ΔIEs for the proposed hypothetical binding modes between the tested analytes with the CME SAMs on the Au-QTF sensing surfaces. [ABSTRACT FROM AUTHOR]

Today, the modification of the organic molecules using the copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC) is of great interest, as evidenced by the Nobel Prize in Chemistry awarded in 2022 to the founder of "click" chemistry. Supramolecular chemistry, in turn, is one of the actively developing branches of modern science. Using the CuAAC approach is a very convenient method to obtain new macrocyclic structures of interest. This review focuses on the use of the modular "click"-chemistry approach for the synthesis of various triazole derivatives of thiacalix[4]arenes and calix[4]arenes as well as general routes for the synthesis of their precursors (azides and alkynes). Examples of some functional systems based on triazole-containing macrocycles, such as chemosensors, multicalixarenes, amphiphilic calixarenes as well as examples of the use of triazole calixarenes for bioapplications are described. [ABSTRACT FROM AUTHOR]

SP 1 sp H NMR (300 MHz, CDCl SB 3 sb ): = 8.69 (d, I J i = 8.0 Hz, 1 H), 7.56-7.55 (m, 2 H), 7.48-7.43 (m, 2 H), 7.35-7.32 (m, 1 H), 7.15-7.09 (m, 4 H), 6.64-6.59 (m, 3 H), 6.50 (d, I J i = 2.4 Hz, 1 H), 5.50 (s, 1 H), 5.39 -5.29 (m, 1 H), 4.69-4.45 (m, 7 H), 4.28 (d, I J i = 13.7 Hz, 1 H), 4.26 (d, I J i = 12.9 Hz, 1 H), 4.15 (d, I J i = 15.0 Hz, 1 H), 3.39 (d, I J i = 13.7 Hz, 1 H), 3.25 (d, I J i = 13.4 Hz, 1 H), 3.20 (d, I J i = 13.5 Hz, 1 H), 3.17 (d, I J i = 12.8 Hz, 1 H), 2.37 (t, I J i = 2.4 Hz, 1 H), 2.36 (t, I J i = 2.4 Hz, 1 H), 1.59 (d, I J i = 6.9 Hz, 3 H), 1.34 (s, 9 H), 1.33 (s, 9 H), 0.85 (s, 9 H), 0.81 (s, 9 H). SP 1 sp H NMR (300 MHz, CDCl SB 3 sb ): = 7.05-7.00 (m, 5 H), 6.86-6.80 (m, 5 H), 4.92-4.66 (m, 4 H), 4.79 (d, I J i = 15.8 Hz, 1 H), 4.53 (d, I J i = 12.6 Hz, 1 H), 4.46 (d, I J i = 12.8 Hz, 1 H), 4.39 (d, I J i = 15.8 Hz, 1 H), 4.28 (d, I J i = 13.6 Hz, 1 H), 4.15 (d, I J i = 13.0 Hz, 1 H), 3.40 (d, I J i = 14.5 Hz, 1 H), 3.30 (d, I J i = 12.7 Hz, 1 H), 3.29 (d, I J i = 13.0 Hz, 1 H), 3.27 (d, I J i = 12.5 Hz, 1 H), 2.65 (t, I J i = 2.4 Hz, 1 H), 2.56 (t, I J i = 2.4 Hz, 1 H), 1.25 (s, 9 H), 1.20 (s, 9 H), 1.01 (s, 9 H), 1.00 (s, 9 H). SP 1 sp H NMR (300 MHz, CDCl SB 3 sb ): = 8.72 (d, I J i = 8.0 Hz, 1 H), 7.61-7.58 (m, 2 H), 7.51-7.46 (m, 2 H), 7.39-7.33 (m, 1 H), 7.18-7.12 (m, 4 H), 6.67-6.62 (m, 3 H), 6.53 (d, I J i = 2.4 Hz, 1 H), 5.54 (s, 1 H), 5.39 -5.29 (m, 1 H), 4.73-4.48 (m, 7 H), 4.31 (d, I J i = 13.6 Hz, 1 H), 4.29 (d, I J i = 12.8 Hz, 1 H), 4.19 (d, I J i = 15.0 Hz, 1 H), 3.43 (d, I J i = 13.9 Hz, 1 H), 3.28 (d, I J i = 13.5 Hz, 1 H), 3.24 (d, I J i = 13.5 Hz, 1 H), 3.20 (d, I J i = 12.8 Hz, 1 H), 2.40 (t, I J i = 2.3 Hz, 1 H), 2.39 (t, I J i = 2.3 Hz, 1 H), 1.65 (d, I J i = 5.8 Hz, 3 H), 1.37 (s, 9 H), 1.36 (s, 9 H), 0.89 (s, 9 H), 0.84 (s, 9 H). [Extracted from the article]

A modular and highly reliable click approach is applied for the expeditious synthesis of lactose- and galactose-coated calixarene-cored G1 and G2 generation glycodendrimers, respectively. The developed calixarene glycodendrimers have been characterized by using extensive spectral analysis including NMR (1H and 13C), MS, IR, and SEC data.

Aim. The purpose of the present study was to develop a method for the fixation of ‘fixed’ conformation for estimation of the impact of calix[4]arene structure on the efficacy of its anticoagulant activity. This was achieved by substitution of the lower rim of C-145 analogue. Methods.Calix[4]arene C-145F (compound 6) was obtained in 4 steps starting with Duff reaction. Calix[4]arene methylene-bis-phosphonic ester 3 was prepared via addition of diisopropylphosphite in presence of metallic sodium to the parent calix[4]arene aldehyde 2. Further steps included Mitsunobu reaction, that afforded dipropoxycalix[4]arene 5 with rather good yields (80%), following the hydrolysis step that resulted in compound 6 in almost quantitative yield. Modeling of 3D-structure of calix[4]arene C-145 and its analogue C-145F was performed in Maestro, Schrodinger software. Results. Using a 2D NMR-NOESY spectroscopy, we can observe a distinct cross-peak between an aromatic singlet with a chemical shift on 7.72 ppm and protons of isopropyl group with a chemical shift on 1.62 ppm, which are moved in the strong field. Conclusions. The easy method of the fixation of conus conformation of calix[4]arene cup will be useful for synthesis of novel functionally active compounds. We believe that further development and study of different calix[4]arenes will help scientists to obtain bioactive molecules that could be prospective anti-thrombotic drugs.

Abstract Introduction Clomipramine is a tricyclic antidepressant acting as a serotonin reuptake inhibitor. Its maximum plasma concentration (Cmax) is 13–310 ng/mL, the therapeutic range is 220–500 ng/mL and its toxic effect appears in doses above 900 ng/mL. Objectives The fabrication of eco-friendly solid-contact ion-selective electrodes to evaluate the concentration of Clomipramine in different matrices based on disposable screen-printed carbon electrode. Methods Disposable screen-printed carbon electrode was utilized as a substrate to fabricate the proposed sensors. The sensors were optimized to determine Clomipramine using calix[4]arene as an ionophore into PVC polymeric membrane to enhance selectivity towards the target analyte. The solid-contact sensor potential stability was improved by the incorporation of graphene nanoparticles transducer layer. Results The sensors were assessed as per the IUPAC recommendations. The linearity range was 1 × 10− 2 to 1 × 10− 5.3 M. The sensors were successfully applied to determine CLM in the pharmaceutical formulation. Furthermore, the ion selective electrodes were applied for Clompiramine assay in spiked plasma for the purpose of Point-of-Care testing to be a diagnostic tool for therapeutic monitoring of the cited central nervous system agent. The findings were statistically compared to the reported method showing no statistically significant difference. Conclusion This work was concerned with developing a green analytical method for the determination of Clomipramine. The proposed SC-ISE was mixed with graphene nanocomposite transducer interlayer. The graphene layer succeeded in preventing the formation of an aqueous layer so resulted in a stable, reproducible standard potential besides the rapid response time.

One of the most appealing approaches for regulating gene expression, named the "microRNA therapeutic" method, is based on the regulation of the activity of microRNAs (miRNAs), the intracellular levels of which are dysregulated in many diseases, including cancer. This can be achieved by miRNA inhibition with antimiRNA molecules in the case of overexpressed microRNAs, or by using miRNA-mimics to restore downregulated microRNAs that are associated with the target disease. The development of new efficient, low-toxic, and targeted vectors of such molecules represents a key topic in the field of the pharmacological modulation of microRNAs. We compared the delivery efficiency of a small library of cationic calix[4]arene vectors complexed with fluorescent antimiRNA molecules (Peptide Nucleic Acids, PNAs), pre-miRNA (microRNA precursors), and mature microRNAs, in glioma- and colon-cancer cellular models. The transfection was assayed by cytofluorimetry, cell imaging assays, and RT-qPCR. The calix[4]arene-based vectors were shown to be powerful tools to facilitate the uptake of both neutral (PNAs) and negatively charged (pre-miRNAs and mature microRNAs) molecules showing low toxicity in transfected cells and ability to compete with commercially available vectors in terms of delivery efficiency. These results could be of great interest to validate microRNA therapeutics approaches for future application in personalized treatment and precision medicine. [ABSTRACT FROM AUTHOR]

The safety storage of hydrogen molecule is an important issue for researchers. Today, hydrogen adsorption and detection is one of these issues. In this study, the interactions of calix[4]arene macrocycle and its metal complexes with hydrogen molecule were investigated by Density Functional Theory (DFT) method. WB97XD hybrid method was used in DFT calculations. The most stable complexes of calix[4]arenes with metal atoms were determined. All interactions were determined to be weak van der Waals interactions. It has been revealed that metal atoms in the complexes have positive effect on adsorption and the best adsorbent is the Fe-calix[4]arene complex. It has been determined that pristine calix[4]arene compound can be used as an electronic sensor against hydrogen molecule at room temperature. [Display omitted] • Calix[4]arene-metal complexes can be used as adsorbent against the hydrogen molecule. • The lowest adsorption energy was calculated as −7.5 kJ/mol for the Fe complex. • p - tert -butylcalix[4]arene compound can be used as hydrogen sensor. [ABSTRACT FROM AUTHOR]

p-Aminophenol is an important organic molecule which is widely used in pharmaceutical as well as in dye industries for the synthesis of various drugs and corrosion resistant paints respectively. In order to synthesize this important organic molecule, CuO nanoparticles were functionalized with diamide derivative of calix[4] arene (3). The functionalized nanoparticles (4) were characterized with different analytical techniques such as FT-IR, XRD, SEM and EDX. The synthesized catalyst (4) was used to convert p-nitrophenol,in presence of sodium borohydride, into p-aminophenol which is an industrially important organic molecule. This reaction was monitored by Ultraviolet visible (UV-Vis) spectroscopy. The catalytic conversion took 35-40 seconds. The reaction followed pseudo first order kinetics and rate constant was determined as 1.386 min−1. N [ABSTRACT FROM AUTHOR]

The spectra of optical absorption, fluorescent emission and fluorescence excitation of the aqueous solutions of Adenosine triphosphate, calix[4]arenes C-107 and their complexes were studied. It was shown that with the formation of heteroassociates of adenosine triphosphate-C-107 the fluorescence of adenosine triphosphate in the narrow concentration range of calix[4]arenes is quenched. [ABSTRACT FROM AUTHOR]

Three chiral diphosphites, (S,S)-5,17-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)-25,26,27,28-tetrapropyloxycalix[4]arene (1), (S,S)-5,11,17,23-tetra-tert-butyl-25,27-dipropoxy-26,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)calix[4]arene (2) and (S,S)-5,11,17,23-tetra-tert-butyl-25,26-dipropoxy-27,28-bis(1,1′-binaphthyl-2,2′-dioxyphosphanyloxy)calix[4]arene (3), based on conical calix[4]arene were investigated in the rhodium-catalyzed asymmetric hydrogenation of α-dehydroamino esters. High conversions were observed after 24 h under 5 bar of hydrogen whatever the employed diphosphite, and the chiral induction increases in the order 1 < 3 < 2. This may be due to the presence of the calix[4]arene moiety, which by its presence modifies the second coordination sphere of the catalytic center. The larger steric hindrance around the rhodium atom leads to the higher enantiomeric excess.

Introduction: Clomipramine is a tricyclic antidepressant acting as a serotonin reuptake inhibitor. Its maximum plasma concentration (Cmax) is 13–310 ng/mL, the therapeutic range is 220–500 ng/mL and its toxic effect appears in doses above 900 ng/mL. Objectives: The fabrication of eco-friendly solid-contact ion-selective electrodes to evaluate the concentration of Clomipramine in different matrices based on disposable screen-printed carbon electrode. Methods: Disposable screen-printed carbon electrode was utilized as a substrate to fabricate the proposed sensors. The sensors were optimized to determine Clomipramine using calix[4]arene as an ionophore into PVC polymeric membrane to enhance selectivity towards the target analyte. The solid-contact sensor potential stability was improved by the incorporation of graphene nanoparticles transducer layer. Results: The sensors were assessed as per the IUPAC recommendations. The linearity range was 1 × 10− 2 to 1 × 10− 5.3 M. The sensors were successfully applied to determine CLM in the pharmaceutical formulation. Furthermore, the ion selective electrodes were applied for Clompiramine assay in spiked plasma for the purpose of Point-of-Care testing to be a diagnostic tool for therapeutic monitoring of the cited central nervous system agent. The findings were statistically compared to the reported method showing no statistically significant difference. Conclusion: This work was concerned with developing a green analytical method for the determination of Clomipramine. The proposed SC-ISE was mixed with graphene nanocomposite transducer interlayer. The graphene layer succeeded in preventing the formation of an aqueous layer so resulted in a stable, reproducible standard potential besides the rapid response time. [ABSTRACT FROM AUTHOR]

Phosphate ester bonds are widely present in nature (e. g. DNA/RNA) and can be extremely stable against hydrolysis without the help of catalysts. Previously, we showed how the combination of phosphoryl and calix[4]arene moieties in the same organic framework (LPO) allows isolation of single lanthanide (Ln) metal ions as [LnIII(LPO)2](O3SCF3)3. Here we report how by controlling the reaction conditions a new hydrolyzed phosphoryl‐calix[4]arene ligand (H3LHPO) is formed as a result of LnIII‐mediated P–OEt bond cleavage in three out of the eight possible sites in LPO. The chelating nature of H3LHPO traps the LnIII species in the form of [LnIII(LHPO)((EtO)2P(O)OH)]2 dimers (Ln=La, Dy, Tb, Gd), where the Dy derivative shows slow magnetization relaxation. The strategy presented herein could be extended to access a broader library of hydrolyzed platforms (HxLHPO; x=1–8) that may represent mimics of nuclease enzymes. [ABSTRACT FROM AUTHOR]

The ionophore has been successfully synthesized from p-t-butyl(carboxymethoxy)calix[4]arene subtituted amide. The ionophore was obtained in two steps of the synthesis reaction. The first step is the chlorination reaction of p-tbutyl(carboxymethoxy)calix[4]arene with thionyl chloride in dry benzene solvent. The product of the chlorination reaction is pt-butyl(chloroacetylmethoxy)calix[4]arene in the form of the light brown viscous liquid with the rendemen of 78.25% and TLC (SiO2, CH3OH: CH2Cl2 = 1: 1 v/v, Rf = 0.65). The second step is the amidation reaction of p-t-butyl(chloroacetylmethoxy) calix[4]arene with dimethylamine in dry tetrahydrofuran solvent. The product of the amidation reaction is p-tbutyl(dimethylcarbamoylmethoxy)-calix[4]arene or the DIMECAC4ND3 ionophore in the form of white solid with the rendemen of 60.75%, a melting point of 277-279 °C, and TLC (SiO2, CH3OH: CH2Cl2 = 1: 1 v/v, Rf = 0.82). [ABSTRACT FROM AUTHOR]

Fusarium mycotoxins are toxic secondary fungal metabolites and widely distributed in cereals. Herein, a nickel ferrite magnetic calix[4]arene-derived covalent organic framework (NiFe 2 O 4 @CX4-COF) was meticulously designed and synthesized using a room-temperature method for the enrichment of mycotoxins. The CX4-COF exhibited a porous crystalline network with an eclipsed AA-stacking configuration. The ingenious integration of NiFe 2 O 4 , supramolecular calix[4]arene and COF contributed to host-guest mediated recognition, size-selectivity and high adsorption capacity, rapidly reaching adsorption equilibrium within only 3 min. Simulation calculations revealed that the host-guest interaction, size effect and abundant binding sites facilitated synergistically recognize and capture mycotoxins. NiFe 2 O 4 @CX4-COF has successfully applied for simultaneous extraction and analysis of mycotoxins in cereals, achieving negligible matrix effects (−14% to 13%), high sensitivity (LODs of 0.003–0.014 μg/L) and satisfactory recoveries (74.4%–116%). This work provides a prospective platform for constructing tailored macrocycle-based COFs under mild conditions for precise recognition and accurate analysis of trace hazardous substances in food. [Display omitted] • Facile room-temperature synthesis of a magnetic calix[4]arene-derived covalent organic framework (NiFe 2 O 4 @CX4-COF). • NiFe 2 O 4 @CX4-COF featured host-guest interaction, size effect and abundant binding sites. • High adsorption capacity, rapid kinetics and precise recognition for Fusarium mycotoxins were realized. • The sensitive analysis of trace Fusarium mycotoxins in cereals was successfully achieved. [ABSTRACT FROM AUTHOR]

A new type of calix[4]arene-bis-1,3-diketone derivatives, in which the chelate groups are directly conjugated through the carbonyl carbon atom to the aromatic moieties of calix[4]arene, demonstrates the dramatic effect of lower rim substituents on the coordination of Eu3+ ions with conjugated 1, 3-diketo groups. Eu3+ -luminescence is more enhanced in complexes with dipropoxy-calix[4]arene compared to complexes with the tetrapropoxy analogue due to the difference in the structure of the complex. [Display omitted] This work presents new type of bis-1,3-diketone calix[4]arene derivatives, in which the chelate groups are directly conjugated through the carbonyl carbon atom with aromatic fragments of calix[4]arene, and their lower rims bear four propoxy groups or pairs of hydroxy and propoxy groups. Tetrapropoxy-calix[4]arene is synthesized by acylation of magnesium enolates of a calix[4]arene ketone with 1-benzoylbenzotriazoles, and the dipropoxy analogue is obtained by bromination of bis(chalcone)-calix[4]arene, followed by methanolysis and hydrolysis. Significant conjugation of 1,3-diketo groups with the π-system of calix[4]arene is revealed for calixarenes of both types. Analysis of complexes formed by the ligands using the UV–Vis and NMR diffusion methods in combination with DFT calculations makes it possible to identify differences in the modes of complex formation of di- and tetrapropoxy- substituted ligands. It is demonstrated that a more enhanced sensibilization of Eu3+-luminescence in complexes with dipropoxy-calix[4]arene compared to that for complexes with tetrapropoxy-counterpart correlates with the formation of a tetrameric structure, in which the binding of Eu3+ ions does not disturb the conjugation of 1,3-diketonate moieties with aromatic calix[4]arene fragments. This is quite different from the significant disturbance of conjugation during intramolecular bis-chelation of Eu3+ ion by 1,3-diketo groups of tetraalkyl substituted ligand. [ABSTRACT FROM AUTHOR]

In this study, a composite film was developed for the electrochemical sensing of tryptophan (Trp). Porous reduced graphene oxide (PrGO) was utilized as the electron transfer layer, and a C-undecylcalix[4]resorcinarene Langmuir–Blodgett (CUCR-LB) film served as the molecular recognition layer. Atomic force microscopy (AFM), transmission electron microscopy (TEM), Raman spectroscopy, scanning electron microscopy (SEM), and electrochemical experiments were employed to analyze the characteristics of the CUCR-LB/PrGO composite film. The electrochemical behavior of Trp on the CUCR-LB/PrGO composite film was investigated, revealing a Trp linear response range of 1.0 × 10−7 to 3.0 × 10−5 mol L−1 and a detection limit of 3.0 × 10−8 mol L−1. Furthermore, the developed electroanalytical method successfully determined Trp content in an amino acid injection sample. This study not only introduces a rapid and reliable electrochemical method for the determination of Trp but also presents a new strategy for constructing high-performance electrochemical sensing platforms.

A hydrophobic calix[4]arene derivative was investigated for its iodine (I2) capture efficiency from gaseous and liquid phase. The iodine uptake was followed by UV-vis spectroscopy. Additionally, the influence of the calix[4]arene derivative–polyolefin system on the leaching of iodine through packaging from a povidone-iodine-based (PVP-I) formulation was evaluated. In fact, iodine is a low-cost, multi-target, and broad-spectrum antiseptic. However, it is volatile, and the extended storage of I2-based formulations is challenging in plastic packaging. Here, we investigated the possibility of reducing the loss of I2 from an iodophor formulation by incorporating 4-tert-butylcalix [4]arene-tetraacetic acid tetraethyl ester (CX) and its iodine complex in high-density polyethylene (HDPE) or polypropylene (PP) via a swelling procedure. Surface and bulk changes were monitored by contact angle, thermogravimetric analysis (TGA), and UV-vis diffuse reflectance spectra. The barrier effect of the different polymeric systems (embedded with CX, iodine-CX complex, or I2) was evaluated by monitoring the I2 retention in a buffered PVP-I solution by UV-vis spectroscopy. Overall, experimental data showed the capability of the calix[4]arene derivative to complex iodine in solution and the solid state and a significant reduction in the iodine leaching by the PP-CX systems. [ABSTRACT FROM AUTHOR]

A novel macrocycle of B/N‐doped calix[4]arene (C‐BN) was synthesized by a one‐shot double boronation. Owing to the structural tension and electron‐donating properties of the nitrogen atoms in the macrocycle, reaction selectively proceeds between the adjacent benzene rings outside the macrocycle. C‐BN shows a highly centrosymmetric structure with two multiple resonance (MR) fragments bridged by tertiary amine groups at the 1,3 positions of the benzene ring. Benefiting from the large intermolecular distance (>4.6 Å) between adjacent MR‐emitting cores, C‐BN also exhibits excellent narrowband emitting features against aggregation‐induced quenching and spectrum broadening. Optimized organic light‐emitting diode devices based on C‐BN exhibit high maximum external quantum efficiencies of 24.7–26.6 % and small full width at half maximums of 25–28 nm over a wide doping range of 1–12 wt %. [ABSTRACT FROM AUTHOR]