Tetraethyl Ester Research Articles

Calix[4]arene Derivative for Iodine Capture and Effect on Leaching of Iodine through Packaging

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.

Tetrathiafulvalene esters with high redox potentials and improved solubilities for non-aqueous redox flow battery applications

The exploitation of high performance redox-active substances is critically important for the development of non-aqueous redox flow batteries. Herein, three tetrathiofulvalene (TTF) derivatives with different substitution groups, namely TTF diethyl ester (TTFDE), TTF tetramethyl ester (TTFTM), and TTF tetraethyl ester (TTFTE), are prepared and their energy storage properties are evaluated. It has been found that the redox potential and solubility of these TTF derivatives in conventional carbonate electrolytes increases with the number of ester groups. The battery with a catholyte of 0.2 mol L−1 of TTFTE delivers a specific capacity of more than 10 Ah L−1 at the current density of 0.5 C with two discharge voltage platforms locating at as high as 3.85 and 3.60 V vs. Li/Li+. Its capacity retention can be improved from 2.34 Ah L−1 to 3.60 Ah L−1 after 100 cycles by the use of an anion exchange membrane to block the crossover of TTF species. The excellent cycling stability of the TIF esters is supported by their well-delocalized electrons, as revealed by the density function theory calculations. Therefore, the introduction of more and larger electron-withdrawing groups is a promising strategy to simultaneously increase the redox-potential and solubility of redox-active materials for non-aqueous redox flow batteries.

An insight into the dual fluorescence of 3,6-dihydroxybenzene-1,2,4,5-tetracarboxylic acid tetraethyl ester – An experimental and theoretical study

The Excited State Intramolecular Proton Transfer (ESIPT) phenomenon involving photo-induced keto-enol tautomerization is known to cause significant variations in the excited state structures and photophysical properties of certain molecules. Here, the dual emission exhibited by 3,6-dihydroxybenzene-1,2,4,5-tetracarboxylic acid tetraethyl ester has been studied both experimentally and theoretically and it is concluded that the second emission is due to ESIPT in polar protic solvents, while it is due to dianion formation in solvents like DMSO and DMF.

Organic Light‐Emitting Diodes Based on a Columnar Liquid‐Crystalline Perylene Emitter

AbstractLiquid crystalline materials possess great potential as emitters in organic light‐emitting diodes (OLEDs) due to their self‐assembling property, which may lead to anisotropic films and improved charge transport. Here, the key photophysical properties of the columnar liquid crystalline emitter perylene‐3,4,9,10‐tetracarboxylic tetraethyl ester (PTCTE) are investigated and the material is implemented into OLEDs. It is found that vacuum‐deposited PTCTE films exhibit preferential horizontal orientation of the transition dipole moment. Embedding the emitter into different host materials leads to increased photoluminescence quantum yield but reduces molecular orientation compared to the neat film. OLEDs containing PTCTE doped into an exciplex‐forming co‐host achieve very high luminance exceeding 10 000 cd m−2 at 5.7 V, which is among the best performances of OLEDs based on columnar liquid crystalline emitters reported so far.

Antimicrobial compounds isolated from Tropaeolum tuberosum

Activity-guided fractionations of black tubers of Tropaeolum tuberosum led to the isolation of 3-[3-(3-pyridinyl)-1,2,4-oxadiazol-5-yl] benzonitrile (1) and [3,5-Bis (1,1-dimethylethyl)-4-hydroxyphenyl] ethenylidene] bis-phosphonic acid tetraethyl ester (2). Compounds 1 and 2 showed an antibacterial effect against almost all the strains assayed, especially compound 2, showing the same inhibition potential for Enterococcus faecalis and Salmonella enteritidis as the ampicillin (MIC = 1.5 μM) and a better potential than chloramphenicol which has a MIC of 3.5 μM. In addition, compounds 1 and 2 showed a relevant antifungal inhibition against Candida tropicalis with MICs of 100 μM and 50 μM, and against Saccharomyces kudriavzevii with MICs of 25 μM and 1.5 μM. This is in comparison to fluconazole which had MICs of 150 μM (against Candida tropicalis) and 3.5 μM (against Saccharomyces kudriavzevii). This is the first time that compounds 1 and 2 are reported as showing antimicrobial activities.

Structure of ruthenium(II) complexes with coproporphyrin I tetraethyl ester

The reaction between coproporphyrin I tetraethyl ester and ruthenium(II) dodecacarbonyl in toluene is investigated. The formation of two different products, complexes 2 and 3 of ruthenium(II) with coproporphyrin I tetraethyl ester, studied by means of mass spectrometry, electronic absorption spectroscopy, NMR, X-ray diffraction, and thermogravimetric analysis, is revealed. Structures are proposed for the products, of which (2) is a monocarbonyl complex of ruthenium(II) porphyrin that exists as a coordination polymer formed owing to intermolecular axial bonding between the oxygen atoms of carboethoxyl groups and ruthenium(II). The structure proposed for second product (3) is in the form of the corresponding monomer of a monocarbonyl complex of ruthenium(II) porphyrin. It is established that polymeric complex 2 transforms into monomeric complex 3 when it is heating in pyridine.

Pregnane X Receptor Activation Attenuates Inflammation-Associated Intestinal Epithelial Barrier Dysfunction by Inhibiting Cytokine-Induced Myosin Light-Chain Kinase Expression and c-Jun N-Terminal Kinase 1/2 Activation.

The inflammatory bowel diseases (IBDs) are chronic inflammatory disorders with a complex etiology. IBD is thought to arise in genetically susceptible individuals in the context of aberrant interactions with the intestinal microbiota and other environmental risk factors. Recently, the pregnane X receptor (PXR) was identified as a sensor for microbial metabolites, whose activation can regulate the intestinal epithelial barrier. Mutations in NR1I2, the gene that encodes the PXR, have been linked to IBD, and in animal models, PXR deletion leads to barrier dysfunction. In the current study, we sought to assess the mechanism(s) through which the PXR regulates barrier function during inflammation. In Caco-2 intestinal epithelial cell monolayers, tumor necrosis factor-α/interferon-γ exposure disrupted the barrier and triggered zonula occludens-1 relocalization, increased expression of myosin light-chain kinase (MLCK), and activation of c-Jun N-terminal kinase 1/2 (JNK1/2). Activation of the PXR [rifaximin and [[3,5-Bis(1,1-dimethylethyl)-4-hydroxyphenyl]ethenylidene]bis-phosphonic acid tetraethyl ester (SR12813); 10 μM] protected the barrier, an effect that was associated with attenuated MLCK expression and JNK1/2 activation. In vivo, activation of the PXR [pregnenolone 16α-carbonitrile (PCN)] attenuated barrier disruption induced by toll-like receptor 4 activation in wild-type, but not Pxr-/-, mice. Furthermore, PCN treatment protected the barrier in the dextran-sulfate sodium model of experimental colitis, an effect that was associated with reduced expression of mucosal MLCK and phosphorylated JNK1/2. Together, our data suggest that the PXR regulates the intestinal epithelial barrier during inflammation by modulating cytokine-induced MLCK expression and JNK1/2 activation. Thus, targeting the PXR may prove beneficial for the treatment of inflammation-associated barrier disruption in the context of IBD.

Interspecies Differences in the Metabolism of a Multiester Prodrug by Carboxylesterases

The pentaethyl ester prodrug of the chelating agent diethylene triamine pentaacetic acid (DTPA) referred to as C2E5 is being developed as an orally bioavailable radionuclide decorporation agent. The predicted human efficacy obtained in these experimental animals is confounded by interspecies variations of metabolism. Therefore, in the present study, carboxylesterase-mediated metabolism of [14C]-C2E5 was compared in the S9 intestinal and hepatic fractions of human, dog, and rat and their respective plasma. Intestinal hydrolysis of C2E5, resulting in the formation of the tetraethyl ester of DTPA (C2E4), was only detected in human and rat. The primary metabolite in human and dog hepatic fractions was C2E4, whereas the predominant species identified in rat hepatic fractions was the triethyl ester (C2E3). Hepatic hydrolysis of C2E5 causes the formation of C2E4 in human, dog, and rat and C2E3 in rat only. Minimal C2E5 hydrolysis was observed in human and dog plasma, whereas in rat plasma C2E5 converted to C2E3 rapidly, followed by slower further metabolism. Both recombinant CES1 and CES2 play roles in C2E5 metabolism. Together, these data suggest that dogs may be the most appropriate species for predicting human C2E5 metabolism, whereas rats might be useful for clarifying the potential toxicity of C2E5 metabolites.

Synthesis and biological evaluation of aminomethylidenebisphosphonic derivatives of β-arylethylamines

Addition of two equivalents of triethyl phosphite to β-arylethylisocyanides to synthesize tetraethyl aminomethylidenebisphosphonates in the presence of a stoichiometric amount of hydrogen chloride is reported. Acid hydrolysis of the tetraethyl esters gave the 2-arylethylaminomethylidenebisphosphonic acids in good yields. Additionally, the obtained bisphosphonates were evaluated for their antiproliferative effect against MCF-7 human breast cancer cells, J774E mouse macrophages and HL-60 human promyelocytic leukemia cells. β-Phenylphenethylamine derivative showed a selective activity towards J774E cells with IC50 values three times lower than Incadronate and twice as high as Zoledronate.

ChemInform Abstract: Copper‐Mediated 1,4‐Conjugate Addition of Boronic Acids and Indoles to Vinylidenebisphosphonate Leading to gem‐Bisphosphonates as Potential Antiresorption Bone Drugs.

A wide range of gem-bisphosphonate tetraethyl esters as precursors for bisphosphonic acids, which are potent inhibitors of bone resorption, bearing alkyl, aryl, and indole substituents in the β position were prepared through the CuII-catalyzed 1,4-conjugate addition of boronic acids and indoles to vinylidenebisphosphonate tetraethyl ester.

Preparative-scale separation of ethyl esters of diethylenetriaminepentaacetic acid by flash chromatography

The penta ethyl ester of diethylenetriamine pentaacetic acid (DTPA) can be used as a prodrug for decorporation of radionuclides in the event of an internal radiation incidents with transuranic elements. A C18 chromatography purification method was successfully developed using a step elution profile to isolate 0.5–3 g of the four ethyl esters of DTPA. Less than 11 % of the isolated di-ethyl and tri-ethyl esters of DTPA, and less than 20 % of the tetra-ethyl ester of DTPA, had degraded in phosphate buffered saline over a 168 h period.

Copper‐mediated 1,4‐Conjugate Addition of Boronic Acids and Indoles to Vinylidenebisphosphonate leading to gem‐Bisphosphonates as Potential Antiresorption Bone Drugs

AbstractA wide range of gem‐bisphosphonate tetraethyl esters as precursors for bisphosphonic acids, which are potent inhibitors of bone resorption, bearing alkyl, aryl, and indole substituents in the β position were prepared through the CuII‐catalyzed 1,4‐conjugate addition of boronic acids and indoles to vinylidenebisphosphonate tetraethyl ester.

Bifunctional polymeric membrane ion selective electrodes using phenylboronic acid as a precursor of anionic sites and fluoride as an effector: A potentiometric sensor for sodium ion and an impedimetric sensor for fluoride ion

A new concept in ion sensing mimicking allosteric membranes in biological systems was proposed and demonstrated using fluoride-effector Na+ selective electrodes (Na-ISEs). DOS-plasticized PVC membranes containing p-tert-butylcalix[4]arene tetraethyl ester (NaX) and 4-[(4-tert-butyl-2-methylphenoxy)methyl]phenyl boronic acid (50mol% compared to NaX) were found to give the best characteristic of Na-ISEs upon conditioning the membranes in 10−2M NaF: a response slope of 57.48mV per decade and detection limit of 7.42×10−7M. The selectivity coefficients (log KNa,jpot) for the optimal electrode were −2.29, −2.84, −3.16, −3.42, and −3.01 for K+, Li+, Cs+, Mg2+ and Ca2+, respectively. The optimal electrodes also gave good reversibility and could be used in a wide range of pH (pH 3.6–9.7). The fabricated Na-ISEs were found to have membrane resistances (Rm) varied with concentrations of fluoride ions used in membrane conditioning steps. Electrochemical impedance spectra showed a linear relationship between Rm and the logarithm of the concentration range of fluoride ions from 1×10−1 to 1×10−8M. Conditioning optimal membranes with various concentrations of Bu4NF gave a non-linear relationship. The proposed membrane electrode, thus, showed permselectivity toward Na+ using F− as an effector. Therefore, the proposed new concept led to the fabrication of a bifunctional sensor: a potentiometric sensor for sodium ion and an impedimetric sensor for fluoride ion.

Low toxicity and unprecedented anti-osteoclast activity of a simple sulfur-containing gem-bisphosphonate: A comparative study

Bisphosphonates (BPs) are key drugs for the treatment of bone resorption diseases like osteoporosis, Paget's disease and some forms of tumors. Recent findings underlined the importance of lipophilic N-containing BPs to ensure high biological activity. Herein we present some unprecedented results concerning the low toxicity and good anti-osteoclast activity of low molecular weight hydrophilic S-containing BPs. A series of S and N-containing BPs bearing aromatic and aliphatic substitution were prepared through Michael addition reaction between vinylidenebisphosphonate tetraethyl ester and the proper nucleophile under basic catalysis. S-containing BPs showed a generally low toxicity, determined with the neutral-red assay using the L929 cell line, and, in particular for an aliphatic one, a good biological activity assessed on primary cultures of human osteoclasts.

An unprecedented octahedral {Cd30} nanocage supported by twelve pendant-armed tetraacetate macrocyclic ligands

An unprecedented octahedral {Cd(30)} nanocage supported by twelve pendant-armed tetraacetate macrocyclic ligands was synthesized through the reaction of macrocyclic tetraethyl ester and Cd(OAc)(2)·2H(2)O in a 1 : 2 stoichiometry, where the surface photovoltage and photoluminescent properties have been studied for the nanocage.

New bifunctional compounds obtained by selective hydrolysis of tetrathiacalix[4]arene tetraethyl esters with Cs2CO3

A new strategy for the synthesis of bifunctional compounds, based on 1,3-alternate tetrathiacalix[4]arene precursors functionalized by pairs of carboxylic acid and ester groups located on opposite sides of the macrocycle platform is described. These building blocks were prepared by the Cs2CO3 induced selective hydrolysis of tetrathiacalix[4]arene tetraester derivatives. A mechanism for the selective hydrolysis is suggested. The structures of the compounds are elucidated by NMR spectroscopic analysis and X-ray single crystal diffraction.

Ultra-High-Sensitive Extraction-Photometric Determination of Sodium Ion Using Flow Injection Analysis with a Chromogenic Calix[4]arene Derivative and a Laser Interferometric Photothermal Detector

A novel flow injection analysis (FIA) system for ultra-high-sensitive determination of Na(+), which involves laser interferometric photothermal equipment as the detector, was designed using a proton-dissociable chromogenic calix[4]arene derivative with a dinitrophenol moiety as the extraction-photometric reagent. The chromogenic calix[4]arene derivative showed an excellent extractability toward Na(+), which reflected the cation-complexing property of the tetraethyl ester derivative of calix[4]arene. As the calibration graph of the Na(+) concentration could be successfully obtained at the nanomolar level by this method, the proposed FIA system was found to be promising for highly sensitive determination of Na(+) in very dilute samples such as supply water and cooling water in power plants.

Elaborating on Efficient Anti‐Proliferation Agents of Cancer Cells and Anti‐Inflammatory‐Based N‐Bisphosphonic Acids

Methylenebisphosponic acid tetraethyl ester (1) was added to 2-azido-7a-e and 2-chloroquinoline-3-chalcones 10a-e in boiling sodium ethanolate solution to give, via Michael addition, tetrazolo[1,5-a]quinoline-8a-d, 13a and 2-chloroquinoline-based bisphosphonates 11a-d, 14a in E-configuration. Further acid hydrolysis afforded the respective BP-acid analogues E-9a-d, 12a-d, 13b, and 14b in excellent yields. Anti-tumor activity screening for the new BP-acids at a dose of 10 µM utilizing 44 different human tumor cell lines representing breast, ovary, prostate, lung, and CNS cancer as well as leukemia and melanoma was carried out. Eight of ten tested compounds exhibited remarkable anti-tumor activity against breast and prostate cancer, and a promising anti-tumor sensitivity toward ovarian cancer and melanoma. Conversely, there was only scattered activity against leukemia and no noticeable action of these BP-acids on CNS or lung cancer. Based on the prediction results (PASS program), anti-inflammatory activity of the new acids was also determined in vivo, by the acute carrageenin induced paw edema in rats. Many of these compounds showed anti-inflammatory properties at a dose of 50 mg/kg body weight.

칼릭스아렌 포로젠을 이용한 다공성 박막의 초기 나노기공 형성과정에 관한 연구

Fourier Transform Infrared Spectroscopy and in-situ Position Annihilation Lifetime Spectroscopy(PALS) analysis of hybrid film, which consist of silsesquioxane(SSQ) and 4-tert-butyl calix[4]arene-O,O`,O,O`-tetraacetic acid tetraethyl ester(CA[4]) have been investigated in order to understand initial formation of nanopore in the next generation porous low-k dielectrics(k , while mesopores(2.5~3.0 nm) induced from self assembled CA[4] have been generated at . It might be due to highly interconnected structure of SSQ/CA[4] 20% hybrid thin film resulting in facile evacuating of decomposed fragment of CA[4] molecule.

A novel and practical synthetic route for the total synthesis of lycopene

A novel route for the total synthesis of lycopene 1 is described. The synthesis is based on: (i) a condensation between 4,4-dimethoxy-3-methylbutanal 4 and methylenebisphosphonic acid tetraethyl ester 5, leading to the C6-phosphonate 6, followed by (ii) a modified Wittig–Horner reaction between 6 and 6-methyl-5-hepten-2-one 7 producing dimethoxy-3,5,9-triene 8, and (iii) another modified Wittig–Horner reaction between C15-phosphonate 2 and C10-triene dialdehyde 3 producing all- E-lycopene. The synthetic steps are easily operated and practical for the large-scale production.