Effect Of Calix Research Articles

Preparation and Characterization of Insecticide/Calix[4]arene Complexes and Their Enhanced Insecticidal Activities against Plutella xylostella.

Applications of supramolecular materials in plant protection have attracted significant interest in recent years. To develop a feasible method to improve the efficacy and reduce the usage of chemical pesticides, the effect of calix[4]arene (C4A) inclusion on enhancing the insecticidal activity of commercial insecticides was investigated. Results showed that all three tested insecticides (chlorfenapyr, indoxacarb, and abamectin) with distinct molecular sizes and modes of action were able to form stable 1:1 host-guest complexes with C4A through simple preparation steps. The insecticidal activities of the complexes against Plutella xylostella were effectively enhanced compared to the guest molecule, with the synergism ratio being up to 3.05 (for indoxacarb). An obvious correlation was found between the enhanced insecticidal activity and the high binding affinity between insecticide and C4A, while the improvement in water solubility may not be a determining factor. The work would provide hints for the further development of functional supramolecular hosts as synergists in pesticide formulations.

Calix[4]arene Bridge Mononitration with tert-Butyl Nitrite: Synthesis of Bridging Chiral p-tert-Butylcalix[4]arene with a Mononitro Bridge Substituent.

To explore the reaction universality of bridge nitration, the mononitration of different p-tert-butylcalix[4]arene derivatives was executed with tert-butyl nitrite as a nitration reagent. The effects of calix[4]arene conformations, substituents on the lower rim, and reaction conditions on bridge mononitration are systematically studied. The bridge nitration of p-tert-butylcalix[4]arene derivatives in 1,3-alternate, 1,2-alternate, and partial cone conformations can be smoothly executed while that of p-tert-butylcalix[4]arene derivatives strictly regulated in a cone conformation cannot. The nitration product complexity shows a positive correlation with the bridge-hydrogen types, and the optimal bridge-mononitrated substrate is calix[4]arene with only one bridge-hydrogen type. The electron-withdrawing substituent on the lower rim is apparently beneficial for the bridge mononitration. As a result, a variety of bridging chiral p-tert-butylcalix[4]arenes with a mononitro bridge substituent have been successfully synthesized. The highest bridge-mononitrated yield can reach 27% from 1,3-alternate p-tert-butylcalix[4]arene biscrown-5 under optimal reaction conditions.

HPLC DETECTION OF ANTITHROMBITIC CALIX[4]ARENE IN BLOOD PLASMA OF ANIMALS

Previously sodium salt of 5,11,17,23-bis (dihydroxyphosphoryl) methylcalix[4]arene (C-145) was shown to be promising antithrombotic agent. Aim. This work was focused on the development of the method for the direct detection of this substance in blood plasma and estimation of pharmacokinetics of this compound. Methods. C-145 was injected into the Wistar rat’s lateral tail vein and into rabbit’s marginal vein of the ear (12 mg/kg) or was administrated per-oral. The anticoagulant effects of C-145 in blood plasma were confirmed by activated partial thromboplastin time (APTT) test. HPLC was performed using Agilent 1100 series (Agilent, USA) on the phase cyano ZorbaxCN Column which parameters were L×I.D. 25 cm×4.6 mm. Results. The maximal antithrombotic effect after the intravenous or per-oral administration of C-145 was observed after 4-6 hours. In particular clotting time in APTT-test in these blood plasma samples was prolonged trice and more (120 s against 46 s in control). Normalization of blood clotting was achieved after 24 hours after the injection. To develop a method for direct C-145 detection in blood plasma we selected samples with maximal prolongation of clotting time. For accurate analysis of blood plasma samples proteins were saturated by 10 % trichloroacetic acid. After neutralization by NaHCO3 samples were prepared using 12-port vacuum unit for solid-phase extraction (Agilent, USA) with a Bond-Elut C18 cartridge. Samples that contained C-145 were eluted by 100% methanol for the HPLC analysis performed on the phase cyano ZorbaxCN Column equilibrated with an acetonitrile solution (ddH2O:AcCN 99:1). Elution was performed using a combined gradient of acetonitrile (100 %) and citrate buffer (0.1 M, pH 6.0). The elution zone of C-145 was detected on the 128th minute at 280 nm. Conclusion. Application of the developed methods allowed us to confirm the direct antithrombotic effect of calix[4]arene C-145 on blood of experimental animals during intravenous administration. Also HPLC technique enabled to detect this substance in blood plasma and most likely could be applied for other biological solutions and could be modified for the quantitative analysis in the pharmacokinetic studies as well.

Investigation of Calix[4]arene Molecule on Electroless Ni-P Alloy on Carbon Steel Substrate and Evaluation of its Corrosion Resistance in 3% NaCl

The autocatalytic nickel bath uses sodium hypophosphite as a reducing agent, sodium citrate as a complexing agent and sodium acetate as an accelerator. The effect of calix[4]arene molecule type H4L named (dicarboxylic acid p-tert-butylcalix[4]arene) was studied and used at various concentrations of 10-3 to 10-6 M to improve the microstructure, the microhadness and properties of nickel deposit obtained. The effect of varying the concentration of H4L, on the deposition rate, the composition, the microstructure and morphology of chemical deposition was studied. The results showed that depending on the concentration of calix[4]arene, the deposition rate decreases from 11, to 7.75 μm/h. The microstructure and microhardness improves significantly at a concentration of 10-6 M of additive. It was also shown that the coating obtained is adherent and compact and the chemical bath has become more stable in the presence of calix[4]arenic additives. Indeed, in both cases, the nickel content decreased with the addition of concentration. This decrease of nickel content might be related to the increase of deposition rate depending on the concentration. The X-ray diffraction analysis revealed peak intensification in the {111} orientation of plane in the presence of a concentration of 10-6 M; this may be in agreement with the results of metallographic study which showed that the coatings are adherent and have a good resistance. Hence, the Vickers microhardness of deposited coatings has a better value (376 HV) at the concentration 10-6 M. The corrosion resistance in 3% NaCl solution has been proven at the same concentration as found. Finally, the cyclic voltammetry and electrochemical impedance spectroscopic studies revealed that the additive strongly influences the cathodic process and affects slightly oxidation of hypophosphite.

Discriminatory antibacterial effects of calix[n]arene capped silver nanoparticles with regard to Gram positive and Gram negative bacteria

Silver nanoparticles capped with nine different sulphonated calix[n]arenes were tested for their anti-bacterial effects against B. subtilis and E. coli at an apparent concentration of 100 nM in calix[n]arene. The results show the para-sulphonato-calix[n]arenes are active against Gram positive bacteria and the derivatives having sulphonate groups at both para and alkyl terminal positions are active against Gram negative bacteria. The calix[6]arene derivative with only O-alkyl sulphonate groups shows bactericidal activity.

Synthesis and Anti-Paracoccidioides Activity of Calix[n]arenes

Fungi are some of the most neglected pathogens in terms of new drug discovery. Paracoccidioidomycosis, an endemic disease to South America, is caused by dimorphic fungi of Paracoccidioides genus. Reasonable citotoxicity, limited efficacy, and frequent use of current commercial antifungals have led to the emergence of resistance. Thus, the development of new antifungals with more selectivity and large spectrum of action is mandatory. In this work, six calix(n)arenes were synthesized and their activity explored against seven isolates of P. brasiliensis and P. lutzii. p-tert- Butylcalix(4)arene (CX1) was the most potent compound against fungal cells and exhibited the lowest toxicity on healthy mammalian cells (V79, hamster lung and MDCK, dog kidney). This is the first report on the effect of calix(n)arenes as growth inhibitors of Paracoccidioides fungi.

Effect of calix[6]pyrrole anion receptor addition on properties of PEO-based solid polymer electrolytes doped with LiTf and LiTfSI salts

In this article the impact of anion receptor (1,1,3,3,5,5-meso-hexaphenyl-2,2,4,4,6,6-meso-hexamethyl-calix[6]pyrrole) on physicochemical and ion transport properties of poly(ethylene oxide)-salt composites is discussed. Two salts, lithium triflate and lithium bis(trifluoromethane) sulfonamide, were tested. It is shown that addition of the anion receptor significantly increases glass transition temperature of the composite suggesting changes in the velocity of segmental motions of the polymeric matrix. Also some discrepancies between crystallinity of the electrolyte measured by means of DSC and the one measured by means of XRD for lithium triflate containing electrolytes are discussed. It is proved that the influence of the anion receptor on electrolyte properties depends on the coordinating properties of the anion. In consequence this two structurally similar anions are found to reveal opposite behavior. In systems containing LiTf significant changes in properties are observed upon receptor addition. Contrastively, LiTfSI does not interact with receptor and obtained samples exhibit non-homogenous structure with consequent receptor participation.

Bio-Relevant Derivatives of Calixarene Phosphonic Acids

The calix[4]arenes functionalized at the macrocyclic upper rim with α-hydroxyphosphonic, α-aminophosphonic or methylnebisphosphonic acid groups were synthesized. The complexes formed between the bio-relevent calix[4]arene derivatives and amino acids or dipeptides as well as inhibition effects of calix[4]arene phosphonic acids on alkyline phosphatases acitiy were studied.

A Cholinesterase Sensor Based on a Graphite Electrode Modified with 1,3-Disubstituted Calixarenes

New cholinesterase sensors based on screen-printed graphite and graphite/epoxy electrodes modified with 1,3-disubstituted calix[4]arenes were developed for the detection of compounds that form host–guest complexes (using copper(II) and oxalate ions as an example). The effect of calix[4]arenes on the biosensor signal was studied under homogeneous and heterogeneous conditions. It was found that the effect of the studied compounds was due to changes in the electrostatic interactions and mobility of enzyme effectors in the electrode layer. Procedures were developed for the determination of Cu(II) by its activating effect in the concentration range 0.05–4.0 mM and of oxalate ions by their inhibiting effect in the concentration range 0.5–20 mM.