Synthesis,characterization and metal ion complexation and extraction capabilities of calix[4]arene Schiff base compounds

The syntheses, characterization and metal ion complexation and extraction capabilities of six new calix[4]arene Schiff base compounds, 5–10, are reported. The preparation of the compounds was achieved by the condensation of 5,17-diamino-11,23-di-tert-butyl-25,27-di-n-butoxy-26,28-dihydroxycalix[4]arene with the appropriate aldehyde (5-bromosalicylaldehyde for 5, 4-anisaldehyde for 6, 4-(dimethylamino)benzaldehyde for 7, 9-anthracenecarboxaldehyde for 8, 1-pyrenecarboxaldehyde for 9, and 9-fluorenecarboxaldehyde for 10) in refluxing ethanol. The compounds were characterized by ¹H and ¹³C NMR spectroscopy, IR spectroscopy, high-resolution mass spectrometry and elemental analysis. The X-ray crystal structures of 7, 8 and 9 (as dichloromethane solvates) revealed that the calixarene molecules adopt H-bond stabilized, distorted-cone conformations and form centrosymmetric dimers in the solid state. Compounds 5–10 did not form host–guest complexes with NEt₄[(bdt)MoO₂(OSiPh₃)] (bdt^2–=benzene-1,2-dithiolate), a potential precursor for biologically relevant oxosulfido-Mo(VI/V) enzyme models; such host–guest complexes have the potential to stabilize these sought-after but highly reactive model compounds. In addition, the capabilities of 5–10 to extract selected metal ions (Ni²⁺, Co²⁺, Cu²⁺, Zn²⁺, Ag⁺, Pb²⁺, Cd²⁺ and Hg²⁺) from an aqueous into an organic phase have been assessed by picrate extraction experiments. Compound 5 displayed exceptional selectivity towards Ni²⁺, compound 7 exhibited enhanced extraction towards all of the metal ions tested and compounds 6, 9 and 10 showed very high selectivity towards Hg²⁺. On the other hand, compound 8 exhibited negligible capacity to extract any of the metal ions tested.     

A Method for Determination of Low Levels of Exposure to 2,4-D and 2,4,5-T

A method has been developed for the determination of trace quantities of 2,4-dichloro-phenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 2,4-dichlorophenol (2,4-DCP), and 2,4,5-trichlorophenol (2,4,5-TCP) in human and rat urine. The method involves acid hydrolysis of the phenolic conjugates, extraction of the free phenols and acids, ethylation with diazoethane, silica-gel column chromatography clean-up of the derivatized urine extract, and gas chromatographic determination using the electron-capture detector. The average recoveries of 2,4-D, 2,4,5-T, 2,4-DCP, and 2,4,5-TCP from rat urine spiked with known amounts of the herbicides and their phenols were 94%, 98%, 92%, and 90%, respectively. The limits of detection for 2,4-D, 2,4,5-T, DCP, and TCP in rat urine were: 0.05, 0.01, 0.10, and 0.01 ppm, respectively. The method was used to analyze urine of rats given various levels of 2,4-D and 2,4,5-T by gavage. Results showed that levels of exposure of 3.75 mcg/kg for 2,4-D and 5.0 mcg/kg for 2,4,5-T in rats can be detected in urine within 24 hr from exposure. Urine samples from occupationally exposed people were analyzed and found to contain 0.2 to 1.0 ppm 2,4-D and 0.05 to 3.6 ppm 2,4,5-T.     

Solvent extraction and self-assembly of nanosized aggregates of p-tert-butyl thiacalix[4]arenes tetrasubstituted at the lower rim by tertiary amide groups and monocharged metal cations in the organic phase

New p-tert-butyl thiacalix[4]arenes functionalized with morpholide and pyrrolidide groups at the lower rim in cone, partial cone, and 1,3-alternate conformations were synthesized, and their receptor properties for monocharged cations (alkali metal and silver ions) were studied using the picrate extraction method and dynamic light scattering (DLS). To evaluate the ability of the p-tert-butyl thiacalix[4]arene derivatives to recognize metal ions, liquid-liquid extraction of their picrate salts has been carried out in a mutually saturated water-dichloromethane system. The degrees of extraction and the extraction constants for monocharged metal cations (Li⁺, Na⁺, K⁺, Cs⁺) have been determined. The ability of the systems, consisting of host and guest molecules, to self-assembly was proved by DLS using a Zetasizer Nano ZS particle size analyzer. It was shown that all the investigated thiacalix[4]arenes are able to form nanoscale particles with silver cations under the experimental conditions. The pyrrolidide derivative in the cone conformation showed both self-association and aggregation processes with lithium cations. The degree of extraction for all the investigated systems that formed nanoscale aggregates in the organic phase was more than 67% and the extraction constants, log K_ex determined by the picrate extraction method, more than 6.     

硝酸胍的单点滴定法快速分析

报道了以Ｓ－ 十二烷基双硫腙－ 苦味酸为载体制备苦味酸根离子电极, 研究了电极的性能, 并以该电极为指示电极研究了硝酸胍的单点滴定分析, 导出了定量关系式。 以０ ．１００ ０ ｍｏｌ／ Ｌ 标准硝酸胍溶液滴定０ ．１００ ０ ｍｏｌ／Ｌ 苦味酸, 控制滴定至９５ ％ ,１０ 次实验的平均值为０ ．１００ ２ ｍｏｌ／Ｌ, 相对标准偏差为０ ．２４ ％ , 滴定至９０％ ～９５ ％ 相对标准偏差小于０ ．３ ％ 。 用该法进行工业硝酸胍含量分析, 数分钟就能完成, 结果与重量法很好吻合。     

A spirobiscalix[4]azacrown: synthesis and complexing properties

The synthesis and complexation properties of a novel type of calix[4]azacrown, in which two cone calix[4]arenes are linked via a spiro C-atom incorporated into polyaminoalkylene chains are presented.     

Cyclic and acyclic S2O2 donor-type ionophores. Ion-pair extraction and transport of Ag(I) picrate, and X-ray confirmation of existence of the ion-pair complex

Extraction and transport behaviors of isomeric oxathia macrocycles (L₂, ortho-; L₃, meta- and L₄, para-isomer) and their structure related open-chain compound (L₁) towards Ag(I) picrate have been examined. From the plot of log (D_Ag(I)/[pic⁻]) vs. log [L]₀ for all of the ionophores were linear with slope near unity, thereby confirming the 1:1:1 complex formations of Ag(I)/ligand/picrate ion to be extracted into the dichloromethane phase. The extractability of an acyclic ionophore was superior to those of the corresponding cyclic ones. In membrane transport experiments, the slow rate of release of Ag(I) from the membrane into the receiving phase seems to be responsible for lower transport efficiency. Upon addition of sodium thiosulfate as a stripping reagent in receiving phase, the efficiency of transport is significantly enhanced in the order of L₁ (acyclic)>L₂ (ortho-)>L₃ (meta-)>L₄ (para-) in accordance with those of log K_ex values. It is hypothesized that the ion-pair complexation of L₁ in extraction step would be more favorable in extraction and transport of Ag(I). Its structure have been confirmed by X-ray diffraction analysis of [Ag(L₁)pic], where L₁=1,10-bis(mercaptobenzylyl)-4,7-dioxadecane.     

Synthesis, solid-state structures and metal ion complexation behavior of 2-picolyloxy lariat ethers

Three new 2-picolyloxy lariat ether compounds are prepared and solid-state structures are determined for two of them. Complexation behavior for a series of lariat ethers with pyridyl-containing side arms toward alkali metal cations and Ag⁺ is assessed by two-phase metal picrate extraction from aqueous solutions into chloroform and in homogeneous solutions by isothermal titration calorimetry in methanol.     

EUROPIUM(III) PICRATE COMPLEXES WITH α-(DIETHOXYPHOSPHORYL)-PROPANONE AND DIETHYL-1-METHYLVINYLPHOSPHATE: SYNTHESES,SPECTROSCOPY AND STRUCTURES

Abstract

The Eu(III) picrate complexes with the isomers α-(diethoxyphosphoryl)propanone and diethyl-1-methylvinylphosphate were synthesized and characterized by elemental analyses, IR spectroscopy and emission spectroscopy. X-ray single crystal analyses show that in both complexes the picrate anions are bidentate, bonded through the phenolic and one o-nitrogroup oxygens. The neutral ligands are bonded only through their phosphoryl oxygens, resulting in tricapped trigonal prism coordination polyhedra with C_3v symmetry.     

Triclinic structural isomer of cerium(III)–picrate complexes with triethylene glycol

Two new isomers of [Ce(NO₃)(Pic)(H₂O)₂(EO3)](Pic) complex (where EO3 = triethylene glycol and Pic = picrate anion) have been synthesized by one-pot reaction and structurally characterized. Both isomers, orange and yellow in color, respectively, have a triclinic P-1 crystal lattice with different unit cell dimension, and Ce(III) adopts a different coordination number. In orange isomer, the Pic anion is chelated to Ce(III) via phenolic and ortho-nitro oxygens in a bidentate mode, while in yellow isomer the Pic anion is chelated only monodentate through the phenolic oxygen. Coordination geometries can be described as a distorted bicapped square antiprism and a distorted tricapped trigonal prism for 1 and 2, respectively. Alcohol groups from EO3 form a 1-D chain with symmetry direction [1 0 0] through intermolecular O–H ··· O hydrogen bonding. Photoluminescence spectra of the complexes showed a broad band at 515–540 nm due to the 5d → 4f transition from the Ce(III) with electric dipole allowed.     

Crystal Structure and Fluorescence Spectra of A Complex of Europium Picrate with N,N,N′,N′-tetraphenyl-3,6,9-trioxaundecanediamide

The title complex Eu(Pic)₃(TTD) crystallizes in space group Pcab with a = 23.714(4), b = 29.245(6), c = 32.035(8)Å, V = 22216(7)ų, Z = 16, D_c = 1.63 g cm^-1, w = 12.5 cm^-1, F(000) = 10976 and its structure was solved and refined to R = 0.083. Two crystallographically different Eu(Pic)₃(TTD) units, in which the coordination numbers of two central ions (Eu1 and Eu2) are nine and ten, respectively, are present in the asymmetric unit. In the ⁷F₀ → ⁵D₀ excitation spectrum of the complex, there are two sharp peaks at 578.5 and 579.0 nm indicating that the complex has two Eu(III) sites. Two different patterns in the ⁵D₀ → ⁷F_j (j = 1-4) luminescence spectrum have been observed (selectively excited ⁵D₀), which further reveals the existence of two Eu(III) sites compatible with the result of the structure determination.