P-tert-Butylcalix[6]arene hexacarboxylic acid as host for Pb(II), Sr(II) and Ba(II).
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ABSTRACT:
SUBMITTER: Adhikari BB
PROVIDER: S-EPMC4491503 | biostudies-literature | 2014 Nov
REPOSITORIES: biostudies-literature
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Project description:Calix[6]arene hexacarboxylic acid binds instantly and with low symmetry to Pb, Sr and Ba. Later a highly symmetric up-down alternating conformation emerges. The solution structures are identical to their p-tert-butylcalix[6]arene hexacarboxylic acid counterparts. With either receptor an octahedral cage is formed around the metal. The transformation from low to high symmetry however proceeds at significantly faster rates for the de-t-butylated host.
| S-EPMC4704459 | biostudies-literature
Project description:Hexa-p-tert-butylcalix[6]arene (1) is believed to adopt a winged conformation in a solution, featured by four phenyl rings perpendicular to the calix basis and two others at 1,4-positions lying down. However, there is some controversy on the occurrence of this conformation because it has never been found in the solid state of calix[6]arenes, regardless of the substitution pattern at lower and upper rims. Here, we have observed the winged-cone conformation for the first time in a solvate form of 1 with dimethyl sulfoxide (DMSO), dimethylformamide, and pyridine. The DMSO molecule is strongly encapsulated into 1 through two OH···O hydrogen bonds with both flattened phenolic moieties, one lp(S)···π and four CH···π interactions with the four perpendicular phenyl rings. This host-guest complex has energy lower by 23.4 kcal mol-1 than the isolated species. In addition, another DMSO solvate form with 1,2,3-alternate conformation was also obtained in this study, and its structure is compared with that of the precedent one. A detailed density functional theory study has also been carried out to understand the energetic relationships among cone conformers, intramolecular hydrogen-bonding patterns, and DMSO encapsulation.
| S-EPMC6641646 | biostudies-literature
Project description:In this paper, we have synthesized a novel chitosan-p-tert-butylcalix[4]arene polymer (CCP) as a highly efficient adsorbent for mercury ion (Hg2+) removal from water. In fact, a lower rim diamine derivative of p-tert-butylcalix[4]arene has been cross-linked with chitosan chain by carbonyl diimidazole (CDI) as the linker. CDI forms a urea linkage between calix[4]arene diamine derivative and amine groups of the chitosan polymeric chain. The structure and properties of the new polymer were characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscope. Also, the adsorption capacity of CCP was studied towards Hg2+ in aqueous medium by inductively coupled plasma-optical emission spectrometry. Interestingly, the results showed a considerable adsorption capacity for CCP in comparison with chitosan. Therefore, CCP can be introduced as a promising adsorbent for the elimination of Hg2+ from wastewaters. Moreover, because of the conformity of adsorption kinetic with pseudo-second-order kinetic models, it can be concluded that chemical adsorption has an important role between functional groups on CCP polymer and Hg2+ ions. In addition, according to Freundlich isotherm, the CCP surface was heterogeneous with different functional groups.
| S-EPMC9128855 | biostudies-literature
Project description:The synthesis of new calix[4]arenes adopting a cone stereoisomeric form bearing two or four azide fragments on the upper rim and water-soluble triazolyl amphiphilic receptors with two or four polyammonium headgroups via copper-catalyzed azide-alkyne cycloaddition reaction has been performed for the first time. It was found that the synthesized macrocycles form stable aggregates with hydrodynamic diameters between 150-200 nm and electrokinetic potentials about +40 to +60 mV in water solutions. Critical aggregation concentration (CAC) values were measured using a micelle method with pyrene and eosin Y as dye probes. The CAC values of tetraalkyl-substituted macrocycles 12a,b (5 µM for both) are significantly lower than those for dialkyl-substituted macrocycles 10a,b (790 and 160 µM, respectively). Premicellar aggregates of macrocycles 10a,b and 12a,b with the dye eosin Y were used for nucleotides sensing through a dye replacement procedure. It is unusual that disubstituted macrocycles 10a,b bind more effectively a less charged adenosine 5'-diphosphate (ADP) than adenosine 5'-triphosphate (ATP). A simple colorimetric method based on polydiacetylene vesicles decorated with 10b was elaborated for the naked-eye detection of ADP with a detection limit of 0.5 mM.
| S-EPMC6122204 | biostudies-literature
Project description:A new series of lanthanide (1-5) and uranyl (6) complexes with a tetra-substituted bifunctional calixarene ligand H2 L is described. The coordination environment for the Ln3+ and UO2 2+ ions is provided by phosphoryl and salicylamide functional groups appended to the lower rim of the p-tert-butylcalix[4]arene scaffold. Ligand interactions with lanthanide cations (light: La3+ , Pr3+ ; intermediate: Eu3+ and Gd3+ ; and heavy: Yb3+ ), as well as the uranyl cation (UO2 2+ ) is examined in the solution and solid state, respectively with spectrophotometric titration and single crystal X-ray diffractometry. The ligand is fully deprotonated in the complexation of trivalent lanthanide ions forming di-cationic complexes 2 : 2 M : L, [Ln2 (L)2 (H2 O)]2+ (1-5), in solution, whereas uranyl formed a 1 : 1 M : L complex [UO2 (L)(MeOH)]∞ (6) that demonstrated very limited solubility in 12 organic solvents. Solvent extraction behaviour is examined for cation selectivity and extraction efficiency. H2 L was found to be an effective extracting agent for UO2 2+ over La3+ and Yb3+ cations. The separation factors at pH 6.0 are: βUO 22+ /La 3+ =121.0 and βUO 22+ /Yb 3+ =70.0.
| S-EPMC9306641 | biostudies-literature
Project description:BackgroundTrazodone (TRZ) is a second-generation non-tricyclic antidepressant derived from a triazolopyridine derivative, which is mainly used to treat emotional disorders and conditions related to depressive disorders.PurposeThis study investigated the design, development and characteristics of polyvinyl chloride (PVC) membrane sensors for trazodone HCl (TRZ).MethodsThe developed sensing membranes were constructed using β-cyclodextrin (β-CD; sensor 1), γ-cyclodextrin (γ-CD; sensor 2) or 4-tert-butylcalix[8]arene (t-BC8; sensor 3) ionophores as sensing materials in addition to ionic sites and dioctyl phthalate in the PVC matrix.ResultsSensors 1, 2 and 3 displayed fast, stable and near-Nernstian response over a relatively wide trazodone concentration range (7.0×10-6-1×10-3, 5.0×10-5-1×10-3and 8.0×10-6-1.0×10-3 M, respectively), with detection limits of 2.2×10-6, 1.5×10-5 and 2.42×10-6 M, respectively in the pH range of 3.0-6.0. The sensors demonstrated good selectivity for TRZ in the presence of different ionic compounds. The accuracy and precision of the proposed sensors were assessed by the determination of 40.7 μg/ml of TRZ, which showed average recoveries of 99.6%, 99.1% and 98.5% with mean relative standard deviations of 2.4%, 2.5% and 2.6% for sensor 1, 2 and 3 respectively. Molecular modeling was used to calculate the host-guest binding energy. The lowest free binding energy was -6.243, -5.752 and -5.7105 kcal/mol for 1:1 stoichiometry host-guest complexes of trazodone and β-CD, γ-CD and t-BC8, respectively, which was in-line with a Nernstian response.ConclusionThe investigated methods can be applied for the determination of TRZ in pharmaceutical preparations. The results of investigated dosage-form of TRZ show good agreement with those using the US Pharmacopeia method.
| S-EPMC6630091 | biostudies-literature
Project description:Tritopic ion-pair receptors can bind bivalent salts in solution; yet, these salts have a tendency to form ion-pairs even in the absence of receptors. The extent to which such receptors can enhance ion pairing has however remained elusive. Here, we study ion pairing of M2+ (Ba2+ , Sr2+ ) and X- (I- , ClO4 - ) in acetonitrile with and without a dichlorooxacalix[2]arene[2]triazine-related receptor containing a pentaethylene-glycol moiety. We find marked ion association already in receptor-free solutions. When present, most of the MX+ ion-pairs are bound to the receptor and the overall degree of ion association is enhanced due to coordinative, hydrogen-bonding, and anion-π interactions. The receptor shows higher selectivity for iodides but also stabilizes perchlorates, despite the latter are often considered as weakly coordinating anions. Our results show that ion-pair binding is strongly correlated to ion pairing in these solutions, thereby highlighting the importance of taking ion association in organic solvents into account.
| S-EPMC7540308 | biostudies-literature
Project description:The synthesis and characterization of a new octahedral Zr(IV) complex of oxygen-depleted N,O-type calixarene ligand comprising two distal-functionalized pyrazole rings have been reported. The cone shape and structure of the prepared complex were confirmed univocally by single-crystal X-ray diffraction and NMR studies. The Zr metal lies at 2.091 Å from the plane of the calixarene ring. This complex has been utilized as an efficient catalyst for the synthesis of Biginelli adducts, bis(indolyl)methanes, and coumarins. This complex (Cl2Zr-calixarene) showed superior activity for these multicomponent reactions in comparison to the corresponding Ti(IV) and Zn(II) analogues. Ferrocene-appended bis(indolyl)methane, prepared using this catalyst, was also evaluated for its anticancer activity against the A-172 cell line.
| S-EPMC9386809 | biostudies-literature
Project description:Two new orthophosphates, BaMn2Fe(PO4)3 [barium dimanganese(II) iron(III) tris-(orthophosphate)] and SrMn2Fe(PO4)3 [strontium dimanganese(II) iron(III) tris-(orthophosphate)], were synthesized by solid-state reactions. They are isotypic and crystallize in the ortho-rhom-bic system with space group type Pbcn. Their crystal structures comprise infinite zigzag chains of edge-sharing FeO6 octa-hedra (point group symmetry .2.) and Mn2O10 double octa-hedra running parallel to [001], linked by two types of PO4 tetra-hedra. The so-formed three-dimensional framework delineates channels running along [001], in which the alkaline earth cations (site symmetry .2.) are located within a neighbourhood of eight O atoms.
| S-EPMC5418802 | biostudies-literature
Project description:Two new alkaline earth metal-organic frameworks (AE-MOFs) containing Sr(II) (UPJS-15) or Ba(II) (UPJS-16) cations and extended tetrahedral linker (MTA) were synthesized and characterized in detail (UPJS stands for University of Pavol Jozef Safarik). Single-crystal X-ray analysis (SC-XRD) revealed that the materials are isostructural and, in their frameworks, one-dimensional channels are present with the size of ~11 × 10 Å2. The activation process of the compounds was studied by the combination of in situ heating infrared spectroscopy (IR), thermal analysis (TA) and in situ high-energy powder X-ray diffraction (HE-PXRD), which confirmed the stability of compounds after desolvation. The prepared compounds were investigated as adsorbents of different gases (Ar, N2, CO2, and H2). Nitrogen and argon adsorption measurements showed that UPJS-15 has SBET area of 1321 m2 g-1 (Ar) / 1250 m2 g-1 (N2), and UPJS-16 does not adsorb mentioned gases. From the environmental application, the materials were studied as CO2 adsorbents, and both compounds adsorb CO2 with a maximum capacity of 22.4 wt.% @ 0 °C; 14.7 wt.% @ 20 °C and 101 kPa for UPJS-15 and 11.5 wt.% @ 0°C; 8.4 wt.% @ 20 °C and 101 kPa for UPJS-16. According to IAST calculations, UPJS-16 shows high selectivity (50 for CO2/N2 10:90 mixture and 455 for CO2/N2 50:50 mixture) and can be applied as CO2 adsorbent from the atmosphere even at low pressures. The increased affinity of materials for CO2 was also studied by DFT modelling, which revealed that the primary adsorption sites are coordinatively unsaturated sites on metal ions, azo bonds, and phenyl rings within the MTA linker. Regarding energy storage, the materials were studied as hydrogen adsorbents, but the materials showed low H2 adsorption properties: 0.19 wt.% for UPJS-15 and 0.04 wt.% for UPJS-16 @ -196 °C and 101 kPa. The enhanced CO2/H2 selectivity could be used to scavenge carbon dioxide from hydrogen in WGS and DSR reactions. The second method of applying samples in the area of energy storage was the use of UPJS-15 as an additive in a lithium-sulfur battery. Cyclic performance at a cycling rate of 0.2 C showed an initial discharge capacity of 337 mAh g-1, which decreased smoothly to 235 mAh g-1 after 100 charge/discharge cycles.
| S-EPMC9866501 | biostudies-literature