Solvent Extraction of Alkali Metal Picrates by Lipophilic Cyclodextrin Derivatives

Lipophilic cyclodextrin (CD) derivatives were prepared to extract alkali metal cations from a water phase into an organic phase. The extraction equilibrium constant, K ex, was determined by the solvent extraction method using UV absorption spectroscopy. Hydroxyl groups at the carbons in the 2,6-positions of CD molecules were dipropylated to add the hydrophobicity for dissolving into organic solvents, and furthermore hydroxyl groups at the carbons in the 3-position of these derivatives were acylated as complexing sites with the alkali metal cations. These CD derivatives formed a 1 : 1 complex with alkali metal cations, except for the case of Li+, and transported the alkali metal cations from a water phase into a benzene phase. The initial concentrations of alkali metal cation and picrate anion in the water phase and that of the CD derivatives in the organic phase strongly influenced the extraction equilibrium. Extraction of the alkali metal cation by the derivative without acyl groups was not detected. K ex values of these CD derivatives are of the same order of magnitude as or larger than those of crown ethers. The order of the K ex values in all cases is Li+ < Na+ < K+ Rb+ Cs+, although these CD derivatives have no special selectivity for the alkali metal cations. The cation extraction mechanism was interpreted by an induced-fit mechanism.     

冠醚的分子设计(XX)——含硫、硒杂环的苯并-15-冠-5的合成及其对阳离子的选择性

冠醚可以选择性配位金属离子 ,形成主 -客体或超分子配合物 .因此 ,冠醚的分子设计、合成 ,尤其是对金属离子的配位能力一直是化学研究领域的热点之一 [1] .为了得到高选择性的功能体系 ,控制主 -客体的配位作用 ,人们开展了广泛的冠醚合成及其配位作用的研究[2～ 4 ] .然而 ,含杂环的苯并冠醚研究较少[5～ 9] .我们曾报道了一系列冠醚对金属离子的配位能力和配位选择性 ,给出了有意义的结果[10 ,11] .本文报道两种新型苯并 -五元含硫、硒杂环 -苯并 -1 5 -冠 -5 (3 )和 (4 )的合成及其对苦味酸碱金属和重金属的萃取性能和选择性 .1　实验部…     

杯芳烃偶氮类衍生物对金属离子的萃取作用

通过杯芳烃的酚羟基的直接烃基化反应,在杯芳烃的下缘引入2,3′-二甲基-4-氨基偶氮苯发色团,得到了一系列杯芳烃偶氮衍生物(n=4,6,8)a-c.研究了它们对碱金属,碱土金属及过渡金属等十种金属离子的萃取作用.结果表明此类杯芳烃偶氮衍生物对过渡金属离子有良好的选择性识别作用,其中空腔较大的杯[8]芳烃偶氮衍生物c的萃取效果尤为显著.     

Five new nervogenic acid derivatives from Liparis nervosa

Five new nervogenic acid derivatives(1-5) have been isolated from Liparis nervosa(Thunb.ex A.Murray) Lindl.Their structures were elucidated on the basis of extensive spectroscopic analysis,including 1D NMR,2D NMR,and HR-ESI-MS.     

碱金属原子簇的结构和稳定性

基于从体心立方碱金属晶体优化确立的多体展开势能函数，本文通过坐标优化研究了碱金属原子簇Ｘｎ（Ｘ＝Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ）的结构和稳定性。发现：（１）Ｘｎ原子簇（ｎ＝４－２１）倾向于形成畸变四面体结构单元，（Ｔｄ）的密堆积，分子表面被三元环（Ｄ３ｈ）所覆盖，其中Ｘ７－Ｘ１５最优化结构中包含五角双锥Ｘ７（Ｄ５ｈ）结构单元，具有区域五重对称轴；（２）“微观晶体碎片”的分层优化结果表明，体心立方、面心     

Formation of metal complex ions from amino acid in the presence of Li+, Na+ and K+ by electrospray ionization: metal replacement of hydrogen in the ligands

Alkali metal cations easily form complexes with proteins in biological systems; understanding amino acid clusters with these cations can provide useful insight into their behaviors at the molecular level including diagnosis and therapy of related diseases. For the purpose of characterization of basic interaction between amino acids and alkali metal, each of the 20 naturally occurring amino acids were ionized in the presence of lithium, sodium and potassium cations by electrospray ionization, and the resulting product ions were analyzed. We focus our attention on the gas phase alkali metal ion-proton exchanged complexes in current study, specifically complexes with serine, threonine, asparagine and glutamine, which share characteristic pattern unlike other amino acids. All amino acids generated [M + H](+) and [M + Na](+) ions, where M stands for the neutral amino acid. Serine, threonine, asparagine and glutamine generated cluster ions of [nM - nH + (n + 1)Na](+) and [nM - (n - 1)H + (n - 1)Na + K](+) , where n = 1-7. While the (M - H + Li) and (M - H + K) species were not observed, the neutral (M - H + Na) species formed by proton-sodium cation exchange had a highly stable cyclic structure with ketone and amine ligand sites, suggesting that (M - H + Na) serves as a building block in cluster ion formation. Cluster ion intensity distributions of [nM - nH + (n + 1)Na](+) and [nM - (n - 1)H + (n - 1)Na + K](+) showed a magic number at n = 3 and 4, respectively. Extensive B3LYP-DFT quantum mechanical calculations were carried out to elucidate the geometry and energy of the cluster ions, and they provided a reasonable explanation for the stability and structure of the cluster ions.     

Molecular structure of 3-aminobenzoic acid complexes with alkali metals

The vibration (FT-IR, FT-Raman), electronic (UV-Vis) and NMR (1H and 13C) spectra for 3-aminobenzoic acid and its alkali metal salts were recorded. The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 3-aminobenzoic acid was studied. The assignment of the vibration spectra was done. Characteristic shifts of band wavenumbers and changes in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 3-aminobenzoates and ionic potential, electronegativity, atomic mass and affinity of metal cations were found. The chemical shifts of protons (1H NMR) and carbons (13C NMR) in the series of studied alkali metals were also observed. Optimized geometrical structures of studied compounds were calculated by ab initio and density functional methods.     

Synthesis of glycyrrhetic acid derivatives

11-Deoxyglycyrrhetinic acid (DGA) (2) was produced by Clemmensen reduction of the C-11 carbonyl of 18β-glycyrrhetic acid (GA) (1). Four derivatives of GA and DGA (3a–3d) were synthesized. Their structures were elucidated using spectral data (IR, mass, ¹H, ¹³C NMR). __________ Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 153–155, March–April, 2008.     

气相中碱金属离子与丝氨酸、亮氨酸和赖氨酸五肽复合物的裂解反应简

为了探索金属离子对含有不同侧链的多肽气相解离的影响,采用质谱法研究了碱金属离子Li+,Na+,K+,Rb+和Cs+分别与丝氨酸、亮氨酸和赖氨酸五肽(分别简写为S5,L5和K5)形成的复合物的裂解反应. 质谱定性结果表明,5种碱金属离子均可以在气相中与丝氨酸、亮氨酸和赖氨酸五肽形成配合比为1：1 和2：1的非共价复合物;竞争反应结果表明,随着碱金属离子半径的增加,它们与3种五肽的结合能力逐渐减弱. 质谱定量结果表明,K+与丝氨酸、亮氨酸和赖氨酸五肽复合物的结合常数分别为8.94×104,2.83×104和2.50×103 L/mol,表明K+与五肽复合物的结合强度按照丝氨酸、亮氨酸和赖氨酸的顺序依次减小. 含不同侧链碱金属离子-五肽复合物的碰撞诱导解离结果表明,复合物的碎裂主要发生在骨架上,丝氨酸五肽复合物最易碎裂,亮氨酸五肽复合物其次,赖氨酸五肽复合物则较难碎裂,且3种复合物的侧链断裂情况也呈现明显差异. 此外,研究了Na+与亮氨酸五肽复合物所产生的碎片离子,分析了不同离子之间的来源关系,并以Dunbar的复合物理论模型为依据,推测在碎裂过程中,碱金属离子可能向五肽的碳端或氮端偏移. 质谱碎片分析结果表明,在2：1的非共价复合物中,第一个碱金属离子与五肽上4个酰胺键的羰基结合,第二个碱金属离子与五肽的羧基氧原子结合.     

Solvent effects on extraction of alkali metal picrates with 15-crown-5 into various organic solvents. Elucidation of fundamental equilibria which govern extraction-efficiency and -selectivity

Extractions of alkali metal (Na-Cs) picrates (MA) with 15-crown-5 (15C5) into various diluents of low dielectric constant were conducted at 25 degrees C. Using the extraction data, the ion-pair formation constants (K(MLA)) in water of 15C5-MA 1:1:1 complexes were determined by an equation derived from the regular solution theory (logK(MLA)=4.43+/-0.27 for Na, 3.27+/-0.42 for K, 3.58+/-0.35 for Rb, and 2.78+/-0.41 for Cs). The actual overall extraction equilibrium constants were obtained by considering the concentrations of the 1:1:1 15C5 complexes and the ion-pair formation between uncomplexed alkali metal and picrate ions in the aqueous phase. The distribution constants of the 15C5 complexes were calculated and their partition behavior is explained by the regular solution theory. Molar volumes and solubility parameters of 15C5 itself and the complexes were determined. Extraction-efficiency and -selectivity of 15C5 for alkali metal picrates were completely elucidated from the standpoint of equilibrium.     

Photometric reagents for alkali metal ions, based on crown-ether complex formation--III. 4'-picrylaminobenzo-15-crown-5 derivatives

An extraction study of alkali metal cations has been made with crown-ether reagents, 4'-picrylaminobenzo-15-crown-5 derivatives (HL). On dissociation in alkaline medium, the orange HL gives the blood-red anion L(-) and extracts alkali metal ions into chloroform as coloured complexes of composition ML.HL or ML. The ease of extraction decreases in the order, K(+) > Rb(+) > Cs(+) > Na(+) > Li(+). The extracted complexes are ML.HL for K(+) and Rb(+), and both ML.HL and ML for Na(+). The Li(+) complex is not extracted. The photometric determination of 10-800 ppm of K(+) is possible in the presence of other alkali and alkaline earth metal ions.     

Consolidating molecular AND logic with two chemical inputs

A novel molecular AND logic gate 1 is demonstrated based on the competition between fluorescence and photoinduced electron transfer (PET). It is constructed according to a 'receptor2-spacer-fluorophore-spacer-receptor1-spacer-fluorophore-spacer-receptor2' format where receptor1 is a tertiary amine, receptor2 is a benzo-15-crown-5 ether and the fluorophore is an anthracene moiety, which are separated from each other by methylene spacers. The fluorescence response in methanol is significantly enhanced only when both H+ and Na+ are the inputs at high enough concentrations in accordance with AND logic. Cs+ behaves similarly to Na+, but with a lower fluorescence enhancement, whereas the other alkali metal cations are not effective. Electrospray ionization mass spectrometry provides evidence for formation of 1:1 and 1:2 (1:metal) complexes with alkali cations, and formation of a 1:2:1 (1:metal:proton) complex in the additional presence of acid.     

Chromanone Derivatives from the Pericarps of Calophyllum polyanthum

Three new chromanone derivatives, calopolyanic acid ( 1 ), isocalopolyanic acid ( 2 ), and isorecedensic acid ( 3 ), were isolated from the pericarps of Calophyllum polyanthum Wall . ex Choisy , along with seven known compounds, apetalic acid, blancoic acid, chapelieric acid, methyl isoapetalate, isoapetalic acid, isocalolongic acid, and recedensic acid. All of these compounds were reported from C. polyanthum for the first time. The structures of 1 – 3 were elucidated by spectroscopic methods.     

A novel rearrangement in electrospray ionization multistage tandem mass spectrometry of amino acid ester cyclohexyl phosphoramidates of AZT

Several amino acid ester cyclohexyl phosphoramidates of AZT as anti-HIV prodrugs were synthesized and investigated by electrospray ionization tandem mass spectrometry (ESI-MS(n)). A novel methoxy group migration from the carbonyl group to the phosphoryl group was observed in ESI-MS2. This migration is believed to be a general pathway for ions with a methyl ester moiety at the gamma-position to a phosphoric acid moiety, which is assisted with metal ions such as Li(+), Na(+) and K(+). Coordination between metal ions with both the carbonyl oxygen and phosphoryl oxygen might be a key factor responsible for this migration.     

N-Heterocyclic carbenes and charge separation in heterometallic s-block silylamides

Addition of the N-heterocyclic carbene (NHC), 1,3-bis(2,6-di-isopropylphenyl)imidazol-2-ylidene (IPr), to equimolar quantities of group 1 and group 2 bis(trimethylsilyl)amides results in the isolation of charge separated species, [M(IPr)(2)](+)[M'{N(SiMe(3))(2)}(3)](-) (M = Li, Na, K; M' = Mg, Ca, Sr, Ba). Although these systems were found to be prone to the separation of oily, most likely liquid clathrate, materials, either slow cooling or careful diffusion of the less polar solvent hexane into toluene solutions yielded nine crystalline heterobimetallic complexes in which the coordination sphere of the cationic group 1 center was found by X-ray diffraction analysis to be provided by two IPr ligands. These derivatives are the first examples of any compounds in which coordination at the central alkali metal cation is provided exclusively by NHC ligands and, for the cases where M = Na, are the first instances of any type in which an NHC ligand is bound to sodium. The anionic group 2-containing component of each compound was found to comprise three bis(trimethylsilyl)amido ligands coordinated in an approximately trigonal array about the divalent metal center. The bonding within the unusual cationic components of the compounds has been investigated by density functional theoretical (DFT) methods. Natural Bond Orbital (NBO) analyses have revealed that the coordination is provided by donation of the sp-hydridized IPr lone pair into the valence s-orbital of the alkali metal cation and are consistent with weaker binding, and consequently more labile solution behavior, as group 1 is descended.     

Polymer-like structures of LiSCN, NaSCN, KSCN, RbSCN, and CsSCN complexes with an armed monoaza-15-crown-5 ether bearing a 3',5'-difluoro-4'-hydroxybenzyl group

Structures of LiSCN, NaSCN, KSCN, RbSCN, and CsSCN complexes with 3',5'-difluoro-4'-hydroxybenzyl-armed monoaza-15-crown-5 ether (5) were investigated. The Li+ and Na+ complexes are (1:1)n polymer-like complexes bridged by hydrogen bonding. On the other hand, the K+, Rb+, and Cs+ complexes are polymer-like complexes bridged by the fluorine atoms of the side arms. The titration calorimetry and 19F NMR titration experiments suggest that one or both fluorine atoms along with the oxygen atom of the phenolic OH group coordinate to the alkali metal ions incorporated in the crown part of a second armed ligand to give polymer-like complexes in solution. The FAB-MS data indicated that larger alkali metal ions form more stable polymer-like complexes.     

Influence of halogenation on the properties of uracil and its noncovalent interactions with alkali metal ions. Threshold collision-induced dissociation and theoretical studies

The influence of halogenation on the properties of uracil and its noncovalent interactions with alkali metal ions is investigated both experimentally and theoretically. Bond dissociation energies of alkali metal ion-halouracil complexes, M+(XU), are determined using threshold collision-induced dissociation techniques in a guided ion beam mass spectrometer, where M+ = Li+, Na+, and K+ and XU = 5-fluorouracil, 5-chlorouracil, 6-chlorouracil, 5-bromouracil, and 5-iodouracil. The structures and theoretical bond dissociation energies of these complexes are determined from ab initio calculations. Theoretical calculations are also performed to examine the influence of halogenation on the acidities, proton affinities, and Watson-Crick base pairing energies. Halogenation of uracil is found to produce a decrease in the proton affinity, an increase in the alkali metal ion binding affinities, an increase in the acidity, and stabilization of the A::U base pair. In addition, alkali metal ion binding is expected to lead to an increase in the stability of nucleic acids by reducing the charge on the nucleic acid in a zwitterion effect as well as through additional noncovalent interactions between the alkali metal ion and the nucleobases.     

Croconic acid and alkali metal croconate salts: some new insights into an old story

The solid-state structures of a series of alkali metal salts of the croconate dianion (C(5)O(5)(2-)) and of croconic acid (H(2)C(5)O(5)) have been determined. The alkali metal croconates were obtained by ring contraction of rhodizonic acid (H(2)C(6)O(6)), upon treatment with alkali metal hydroxides and recrystallisation from water. The novel species Na(2)C(5)O(5) x 2H(2)O, Rb(2)C(5)O(5) and Cs(2)C(5)O(5), as well as the mixed hydrogencroconate/croconate salt K(3)(HC(5)O(5))(C(5)O(5)) small middle dot2 H(2)O are described and compared with the Li(+), K(+) and NH(4)(+) salts. Single crystals of croconic acid were obtained by crystallisation of croconic acid in the presence of HCl. Crystal structure determinations showed that the C(5)O(5)(2-) ions tend to organize themselves in columns. The interplanar separations lie in the narrow range 3.12-3.42 A and do not necessarily reflect the presence of pi-stacking interactions. It is argued that the small interplanar separation is the result of a compromise between packing of flat croconate units and the spherical cations together with the water molecules that fill the coordination spheres of the alkali metal atoms.     

Stability evaluation of alkali metal standard solutions by using precise ion chromatography

Mass fractions of alkali metal (Li, Na, K, Rb, Cs) standard solutions (1000 mg/kg) were measured with about 0.1% relative standard deviation by improving the method of injection in ion chromatography (IC). This technique was applied to stability testing of the standard solutions. After storage of each alkali metal standard solution for 18 months, an increase of the mass fraction was observed, for all the alkali metal ions, of approximately 0.15% per year at 25 °C and approximately 0.02% per year at 5 °C. The observed increase of the mass fraction can be explained by the weight loss of the solution during storage. The deviation between the mass fraction measured by IC and the preparation mass fraction after correcting the weight loss for solvent evaporation was within ±0.05% for every alkali metal ion. It is concluded that alkali metal standard solutions of 1000 mg/kg are basically stable for more than 18 months under these storage conditions and that correction for evaporation is effective if weight monitoring of each bottle is performed precisely. Presented at BERM-11, October 2007, Tsukuba, Japan.     

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.