Alkali Metal Picrate Extraction Research Articles

Synthesis, crystal structure, and alkali metal picrate extraction capabilities of molecular clips based on diphenylglycoluril and benzocrown ethers

A convenient method for the synthesis of a series of molecular clips based on the diphenylglycoluril framework and benzocrown ether moieties by the reaction of bis(cyclomethoxymethylene)diphenylglycoluril with benzocrown ethers in polyphosphoric acid is proposed. X-ray diffraction analysis of molecular clips with the benzo-12-crown-4 and benzo-15-crown-5 fragments showed that both compounds are chloroform solvates with the stoichiometry clip:chloroform 1:1. By theoretical and experimental methods the existence of obtained clips in an anti–anti conformation was proved. The complexation properties of the obtained molecular clips were examined toward alkali metal and ammonium ions by FABMS spectrometry and extraction experiments.

Alkali Metal Ion Complexation of Adamantane Functionalized Diaza-bibracchial Lariat Ethers

A series of adamantane functionalized diaza-lariat ethers 1–6 have been prepared and alkali metal picrate extraction profiles determined. The ability of aza-crown ethers 1–6 to extract the alkali metal picrates was compared with that of diaza-18-crown-6 (7) and N,N '-dibenzodiaza-18-crown-6 (8). Na+ and K+ transport across bulk liquid membrane was also measured. The results of alkali metal cation extraction experiments showed that lariat ethers 2 and 3, in which the adamantane molecule is linked to the diaza-18-crown-6 by amine bond, have better complexation abilities for all cations compared to the parent crown ethers 7 and 8, as well as a significantly higher selectivity for K+ than diaza-18-crown-6. However, diazalariat ether 1 showed reduced, and 4–6 negligible extractability towards any of the alkali cations. Monte Carlo conformational analysis pointed to the importance of conformational flexibility of the investigated compounds for their extraction ability of alkali cations.

Synthesis and Alkali Metal Picrate Extraction Capabilities of Novel Bis(benzocrown Ether)s Based on Diphenylglycoluril

Synthesis and Alkali Metal Picrate Extraction Capabilities of Novel Bis(benzocrown Ether)s Based on Diphenylglycoluril

Dendritic effects of crown ether-functionalized dendrimers on the solvent extraction of metal ions

The ability of a series of crown ether-functionalized dendrimers to function as alkali metal picrate extraction agents is assessed by liquid–liquid extraction and 1H NMR titration experiments. Crown ether-functionalized dendrimers that contain Fréchet-type poly(benzyl ether) dendrons of different generation as building blocks display different extraction characteristics toward alkali metal cations. Positive and negative dendritic effects depending on the generation of the dendrimer are assigned in the complexation behaviour of the dendritic host compounds.

Extraction of Alkali-Metal Picrates by Calixarene Esters in the Water–Nitrobenzene Solvent System. The Medium Effect on the Partition and Extraction Processes

Based on distribution data involving alkali-metal (Na+, K+, Rb+ and Cs+) picrates in the presence and in the absence of calix[n]arene (n = 4, 6) esters, the extraction ability of these macrocycles in the water–nitrobenzene solvent system is established. Thus, partition and distribution constants in the mutually saturated solvents and ion-pair formation constants in the water saturated organic phase are calculated from distribution data in the absence of these macrocycles. From distribution data in the presence of the ligand, the extraction and the distribution constants are calculated. Within the experimental error, good agreement is found between the distribution constants calculated from distribution data in presence and absence of calixarenes. The individual processes which contribute to the overall extraction of these cations from water to nitrobenzene are discussed. The medium effect on the extraction process is analysed taking into account previously reported data for these systems in water–dichloromethane and water–chloroform.

Benzo-containing cage-annulated crown ethers: A new class of Ag(I) complexants

Six novel cage-annulated crown ethers, 1-6, that contain 1,2-, 1,3- and 1,4-disubstituted benzene moieties have been prepared. The results of alkali metal picrate extraction experiments performed by using 1-6 as host systems generally are in accord with expectations based upon consideration of the familiar size-fit principle. None of these compounds area particularly avid alkali metal cation complexants; in addition, they display only moderate selectivity in their binding properties toward alkali metal cations. The ability of 1-6 to function as Ag(I) complexants has been assessed via silver picrate extraction experiments and by flame atomic absorption spectrophotometry (FAAS). Compound 4, and to a somewhat lesser extent compounds 6, 3, and 2, proved to be the most avid Ag(I) complexants among the six host systems studied.

Ethyl p-tert-butylcalix(4)arene ethanoate: The role of acetonitrile in the extraction of alkali-metal picrates and on the X-ray structures of the sodium complexes

Distribution data for alkali metal picrates in the water–chloroform solvent system in the absence and in the presence of acetonitrile were used to determine the partition constants of the dissociated electrolytes in the mutually saturated solvents and the ion-pair formation constants in the water saturated organic phase. These data were compared with those previously reported in water–benzonitrile and water–dichloromethane solvent systems. The same experiments carried out in the presence of ethyl p-tert-butylcalix(4)arene tetraethanoate, EtCalix(4), led to the calculation of distribution and extraction constants in these solvent systems. The presence of acetonitrile in the organic phase enhances significantly the extraction constant to an extent that these are the highest values so far obtained in the solvent systems investigated. This enhancement in extraction is attributed to metal complex stabilization promoted by the presence of acetonitrile in the hydrophobic cavity of the ligand. The X-ray structures of two sodium complexes (picrate as the counter-ion), isolated from water saturated chloroform with and without acetonitrile are reported for the first time. In the first complex, the macro-cycle is sited on a crystallographic four-fold axis and hosts an acetonitrile solvent molecule in its calix and a sodium ion in its hydrophilic cavity. The metal is in a eight-fold Archimedean square anti-prism environment, coordinated to the phenol oxygen atom and to the carbonyl oxygen atom of the four rotationally symmetry related pendant arms. The macro-cycle of the other complex adopts a slightly distorted cone conformation and its hydrophilic cavity also hosts a sodium ion. But now the metal is in a seven-fold environment, coordinated to the four phenol oxygen atoms and to the carbonyl oxygen atoms of three pendant arms acting as bidentate ligands. The fourth, mono-dentate, pendant arm points away from the hydrophilic cavity and its terminal –CH2-CH3 group interacts hydrophobically with the calix of a neighboring complex giving rise to a supra-molecular polymeric structure in the lattice.

Synthesis and Complexing Property of Four‐Bridged Crownopaddlanes.

Abstract A new series of crown compounds crownopaddlanes 3a–c bearing three cyclobutane rings were prepared by means of intramolecular [2+2] photocycloaddition of styrene derivatives. The yield of crownopaddlane 3b possessing five ethereal oxygen atoms was remarkably high 52% with the addition of sodium borofluoride in the photoreaction system. As this template effect suggests, 3b showed extraordinarily high Na+-selectivity with high efficiency on the liquid–liquid extraction of alkali metal picrates, though 3a having four ethereal oxygen atoms did not extracted any cations in this system. The high Na+-selectivity of 3b was further clarified by the equilibrium stability constants (log Ka) for Na+ (5.85) and K+ (2.91) in acetonitrile solution. The complexation of 3b to Na+ cation was also examined by X-ray crystallography. Crownopaddlane 3c bearing six ethereal oxygen atoms also efficiently and selectively extracted alkali metal cations, compared with conventional 18-crown-6 derivatives.

Cation Selectivity of a Folded Ditopic Crown Receptor

The synthesis and cation binding properties of a folded ditopic crown receptor, 3, are described. Intramolecular hydrogen-bonding interactions preorganize ditopic crown 3 into a helical conformation that positions the crown moieties in a manner that favors the formation of an intramolecular sandwich cation complex. Alkali-metal picrate extraction studies demonstrate that ditopic crown 3 exhibits a significantly different cation selectivity than mono-crown congener 2. A crystal structure of 3•2KClO4 indicates that two molecules of the complex are assembled into a molecular square in the solid state.

Synthesis and complexing property of four-bridged crownopaddlanes

A new series of crown compounds crownopaddlanes 3a– c bearing three cyclobutane rings were prepared by means of intramolecular [2+2] photocycloaddition of styrene derivatives. The yield of crownopaddlane 3b possessing five ethereal oxygen atoms was remarkably high 52% with the addition of sodium borofluoride in the photoreaction system. As this template effect suggests, 3b showed extraordinarily high Na +-selectivity with high efficiency on the liquid–liquid extraction of alkali metal picrates, though 3a having four ethereal oxygen atoms did not extracted any cations in this system. The high Na +-selectivity of 3b was further clarified by the equilibrium stability constants (log K a) for Na + (5.85) and K + (2.91) in acetonitrile solution. The complexation of 3b to Na + cation was also examined by X-ray crystallography. Crownopaddlane 3c bearing six ethereal oxygen atoms also efficiently and selectively extracted alkali metal cations, compared with conventional 18-crown-6 derivatives.

Solvent Extraction of Metal Picrates with Oligoethylene Glycol Glyme Derivatives

AbstractThe cation‐binding by a series of oligoethylene glycol glyme derivatives has been performed by the solvent extraction of alkali metal picrates between water and dichloromethane. The effect of the length of the oligoethylene unit and the substituents at the terminal group on the cation binding ability is discussed. The results are compared with those of commercially available crown ethers and it was found that the compounds have lower cation binding ability.

Stabilization of a K + -( bis -Cage-Annulated 20-Crown-6) Complex by Bidentate Picrate

Bis-cage-annulated 18-crown-6 and 20-crown-6 macrocyclic ethers (i.e., 1 and 2, respectively) have been synthesized, and their alkali metal picrate extraction profiles have been determined. Host system 1 proved to be a significantly more avid alkali metal cation complexant than 2 and somewhat more avid than 18-crown-6. Both 1 and 18-crown-6 display modest selectivity toward K+ and Rb+. A stable host–guest complex was prepared by slow evaporation of a CH2Cl2–hexane solution of an equimolar mixture of 2 and potassium picrate. The X-ray crystal structure of this complex reveals that picrate anion functions as a bidentate ligand therein. The gas-phase interaction energy between the 2 ⋅ K+ complex and picrate anion was calculated to be ca. −64.9 kcal mol−1, thereby indicating that participation of picrate anion as an additional bidentate ligand results in significant stabilization of complex 10.

Synthesis and alkali metal picrate extraction studies of lower rim functionalized p- tert-butylcalix[4]arene crown ethers

The syntheses of four new calix[4]arene receptors, i.e. 4– 7 , each of which contains an oxahexacyclic cage moiety, are reported. The structures of two of these receptors, i.e. 4 and 7 , have been established via single crystal X-ray structural analysis. The complexation properties of 4– 7 were determined via a series of alkali metal picrate extraction experiments. Two of the cage-functionalized calix[4]arene-crown-5 hosts, i.e. 4 and 5 , display somewhat greater extraction avidity toward Na + picrate vis-à-vis the remaining alkali metal picrates. By way of contrast, host systems 6 and 7 function effectively as a moderately selective K + extractants and display significantly increased extraction avidity toward K + picrate vis-à-vis 4 and 5 .

Synthesis and alkali metal binding properties of novel N-adamantylaza-crown ethers

New N-adamantylaza-crown ethers 1– 8 have been synthesized and their respective alkali metal picrate extraction profiles have been obtained. These results are compared with the results obtained for the parent aza-18-crown-6 and N-benzylaza-18-crown-6. Among the crown hosts studied, 2 , and 6 , proved to be the best alkali metal picrate extractants and displayed significant levels of complexation with K + and Rb +.

Substitution effect, absorption, and fluorescence behaviors of 11,12-benzo-1,7,10,13-tetraoxa-4-aza- cyclopentadec-11-ene (benzoaza-15-crown-5) derivatives upon cation complexation in solvent extraction.

Substitution effect, absorption, and fluorescence behaviors of some benzoaza-15-crown-5 derivatives upon cation complexation in solvent extraction were studied. The introduction of a substituent on the nitrogen atom in benzoaza-15-crown-5 enhanced extractabilities in the solvent extraction of aqueous alkali metal picrates. The nondonating substituents raised the cation selectivity for Na(+) over K(+), but the donating substituents reduced the cation selectivity. The absorption and fluorescence spectral behavior was different with the alkali metal cations.

ChemInform Abstract: Synthesis, Alkali Metal Picrate Extraction, and Alkali Metal Cation Binding Selectivities of Some New Cage‐Annulated Polyoxamacrocyclic Crown Ethers.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Extraction of alkali metal picrates with 18-crown-6, benzo-18-crown-6, and dibenzo-18-crown-6 into various organic solvents. Elucidation of fundamental equilibria governing the extraction-ability and -selectivity.

18-クラウン-6, ベンゾ-18-クラウン-6, ジベンゾ-18-クラウン-6のアルカリ金属イオン抽出能及び抽出選択能に対する溶媒効果, クラウンエーテル (L) の大きさと構造柔軟性, そしてベンゾ基等の影響を平衡論により定量的に解明する目的で, これらのクラウンエーテルとアルカリ金属ピクリン酸塩 (MA) との1 : 1 : 1錯体 (MLA) に関して, 種々の低誘電率希釈剤への全抽出定数と分配定数, そして水中におけるイオン対生成定数を25℃で決定した. 更に, すべてのクラウンエーテルについて, 分配定数を25℃で測定した. クラウンエーテル自身とMLA錯体の分配挙動は, クロロホルムの場合を除いて, 正則溶液論で説明することができた. LとMLA錯体のモル体積と溶解パラメーターを決定した. これら三つのクラウンエーテルのMAに対する抽出能及び抽出選択能 (K+>Rb+>Cs+>Na+>Li+) を四つの素平衡定数を用いて詳細に考察し, 本研究の目的を達成した.

Synthesis, alkali metal picrate extraction, and alkali metal cation binding selectivities of some new cage‐annulated polyoxamacrocyclic crown ethers

AbstractFive new cage‐annulated crown ethers, i.e., 4a, 4b, 6b, 11a, and 11b, have been synthesized and their respective alkali metal picrate extraction profiles along with that of a previously synthesized host molecule, 6a, have been obtained. These results are compared with the corresponding results obtained for electrospray ionization mass spectrometric (ESI‐MS) measurements of relative binding selectivities displayed by the same hosts toward a series of alkali metal chlorides. Among the crown‐5 hosts studied, 6a displays enhanced avidity toward complexation with K+ picrate in liquid‐liquid extraction experiments. Among the three crown‐6 hosts, 4b proved to be the best alkali metal picrate extractant and displayed significant levels of avidity toward complexation with the larger alkali metal cations (i.e., K+, Rb+, and Cs+). The trends in the picrate extraction and the ESI‐MS results obtained herein show several notable similarities and some differences. The similarities generally stem from size‐selective binding properties that are intrinsic to the different cavity sizes of the cage‐annulated macrocycles, whereas the differences reflect the important influence of solvation effects on the binding properties of the macrocycles.

Synthesis, Alkali Metal Picrate Extraction Properties, and X-Ray Crystal Structure of a Novel, Cage-Annulated Monoaza-18-Crown-6 Host

Compound 5, a cage-annulated monoaza-18-crown-6 macrocyclic polyether, has been synthesized, and its alkali metal picrate extraction capabilities have been assessed relative to those of the parent monoaza-18-crown-6 host system. It was observed that both 5 and monoaza-18-crown-6 are selective K+ picrate extractants; however, 5 appears generally to be a somewhat more efficient alkali metal picrate extractant than monoaza-18-crown-6. Interestingly, both the avidity and selectivity of 5 toward extraction of alkali metal picrates from aqueous solution into CHCl3 appears to be pH dependent. In addition, the X-ray crystal structure of an unusual hydronium ion complex of 5 [i.e., 5(HCl)(H2O)-(CHCl3)2] has been determined. The X-ray structure thus determined is compared with the corresponding structure of 5(HCl)(H2O) that has been calculated via application of B3LYP Density Functional Theory.

Synthesis and Alkali Metal Picrate Extraction Studies of p- tert-Butylcalix[4]arene Crown Ethers Bridged at the Lower Rim with Pyridyl Units

The syntheses of pyridyl containing calix[4]arene receptors ( 4, 5, and 11) that adopt the cone conformation are reported. The complexation properties of these host molecules were estimated via the results of alkali metal picrate extraction experiments. A singly-bridged bis-calix[4]arene, i.e. 4 does not appear to be an efficient alkali metal picrate extractant. A doubly-bridged bis-calix[4]arene, i.e. 5, displays elevated extraction avidity toward Rb + and Cs + picrates when compared with that of 4. A pyridyl containing calix[4]arene-crown-5, i.e. 11, shows improved avidity and selectivity toward extraction of K + and Rb + picrates vis-a-vis the corresponding behavior of 4 and 5.