冠醚配合物热力学性质的研究(Ⅴ)——碱金属及碱土金属离子与2,3-苯并-11-甲基-18-冠-6的配位反应的量热滴定研究

用自制滴定量热计研究了70%(W/W)甲醇中2,3-苯并-11-甲基-18-冠-6(BC1-18C6)与Na、K、Rb、Cs、Ca、Mg、Sr、Ba8种碱金属与碱土金属氯化物的配位作用,直接计算了配合物稳定常数及配位反应热函,获得了碱金属与碱土金属稳定性及热函大小的相对顺序.     

Fluorometric sensing of alkali metal and alkaline earth metal cations by novel photosensitive monoazacryptand derivatives in aqueous micellar solutions

Novel monoazacryptand-type fluorescent chemosensors, (derived from an 18-crown-6) and (derived from a 15-crown-5) both with a pyrene ring as their photoresponsive moiety, were synthesized. Their fluorescence properties for alkali metal and alkaline earth metal cations in water were then examined. The detection of metal cations was accomplished by a change in the fluorescence intensity of the host compounds, based on a photoinduced electron transfer (PET) mechanism. In aqueous solution, showed little fluorescence upon the addition of Ba2+ because of the very weak complexation with Ba2+, but the presence of micelles of polyoxyethylene(10) isooctylphenyl ether (Triton X-100) enabled to show highly sensitive and selective Ba2+ detection among alkali metal and alkaline earth metal cations. With respect to the selective fluorescent detection of important metal cations (Na+, K+, Mg2+, Ca2+) relevant to living organisms, was found to detect K+ with high selectivity in aqueous micellar solutions of polyoxyethylene(20) sorbitan monostearate (Tween-60). The selectivity for metal cations was mainly dependent on the goodness of fit of the host cavity and the metal cation size. In the presence of anionic surfactants, detected alkaline earth metal cations more effectively than alkali metal cations.     

The solvent extraction of alkali metal picrates with 4,13-N,N'-dibenzyl-4,13-diaza-18-crown-6

Extraction of alkali metal picrates with N,N'-dibenzyl-18-crown-6 was carried out, with dichloromethane as water-immiscible solvent, as a function [ligand]/[metal cation]. The extractability of metal picrates (Li(+), Na(+), K(+), Rb(+), Cs(+)) was evaluated as a function of [L]/[M(+)]. The extractability of complex cation-picrate ion pairs decreases in this sequence: Li(+)>Rb(+)>Cs(+)>K(+)>Na(+). The overall extraction equilibrium constants (K(ex)) for complexes of N,N'-dibenzyl-18-crown-6 with alkali metal picrates between dichloromethane and water have been determined at 25 degrees C. The values of the extraction constants (logK(ex)) were determined to be 10.05, 6.83, 7.12, 7.83, 6.73 for Li(+), Na(+), K(+), Rb(+) and Cs(+) compounds, respectively. DB186 shows almost 2-fold extractability against Li(+) compared to the other metal picrates, whereas it shows no obvious extractability difference amongst the other metal cations when [L]/[M(+)] is 0.2-1. However, an increasing extractability is observed for Cs(+) when [L]/[M(+)] [1].     

Synthesis and Properties of 5-Chloro-8-hydroxyquinoline-Substituted Azacrown Ethers: A New Family of Highly Metal Ion-Selective Lariat Ethers

New 5-chloro-8-hydroxyquinoline (CHQ)-substituted aza-18-crown-6 (4), diaza-18-crown-6 (1), diaza-21-crown-7 (2), and diaza-24-crown-8 (3) ligands, where CHQ was attached through the 7-position, and aza-18-crown-6 (11) and diaza-18-crown-6 (10) macrocycles, where CHQ was attached through the 2-position, were prepared. Thermodynamic quantities for complexation of these CHQ-substituted macrocycles with alkali, alkaline earth, and transition metal ions were determined in absolute methanol at 25.0 degrees C by calorimetric titration. Two isomers, 1 and 10, which are different only in the attachment positions of the CHQ to the parent macroring, exhibit remarkable differences in their affinities toward the metal ions. Compound 1 forms very stable complexes with Mg(2+), Ca(2+), Cu(2+), and Ni(2+) (log K = 6.82, 5.31, 10.1, and 11.4, respectively), but not with the alkali metal ions. Ligand 10 displays strong complexation with K(+) and Ba(2+) (log K = 6.61 and 12.2, respectively) but not with Mg(2+) or Cu(2+). The new macrocycles and their complexes have been characterized by means of UV-visible and (1)H NMR spectra and X-ray crystallography. New peaks in the UV spectrum of the Mg(2+)-1 complex could allow an analytical determination of Mg(2+) in very dilute solutions in the presence of other alkali and alkaline earth metal cations. (1)H NMR spectral and X-ray crystallographic studies indicate that ligand 10 forms a cryptate-like structure when coordinated with K(+) and Ba(2+), which induces an efficient overlap of the two hydroxyquinoline rings. Such overlapping forms a pseudo second macroring that results in a significant increase in both complex stability and cation selectivity.     

Ultrafine Na-4-mica: uptake of alkali and alkaline earth metal cations by ion exchange

The cation exchange properties of alkali and alkaline earth metal cations at room temperature were investigated on an ultrafine, highly charged Na-4-mica (with the ideal mica composition Na4Mg6Al4Si4O20F4.xH2O). Ultrafine mica crystallites of 200 nm in size led to faster Sr2+ uptake kinetics in comparison to larger mica crystallites. The alkali metal ion (K+, Cs+, and Li+) exchange uptake was rapid, and complete exchange occurred within 30 min. For the alkaline earth metal ions Ba2+, Ca2+, and Mg2+, however, the exchange uptake required lengthy periods from 3 days to 4 weeks to be completed, similar to its Sr uptake, as previously reported. Kinetic models of the modified Freundlich and parabolic diffusion were examined for the experimental data on the Ba2+, Ca2+, and Mg2+ uptakes. The modified Freundlich model described well the Ba2+ ion uptake kinetics as well as that for the Sr2+ ion, while for the Ca2+ and Mg2+ ions the parabolic diffusion model showed better fitting. The alkali and alkaline earth ion exchange isotherms were also determined in comparison to the Sr2+ exchange isotherm. The thermodynamic equilibria for these cations were compared by using Kielland plots evaluated from the isotherms.     

Molecular Complexes of Crown Ethers: Part 8. Effect of Surfactant on the Charge Transfer Complexes of 18C6 with Picric Acid in the Presence of Alkali Metal Ions

The interaction of 18-crown-6 (CE) with picric acid(PA) was studied in the UV-Visible region in 1,2-dichloroethane (DCE) at 298.2 K. The effect of the surfactant Triton X-100 was studied, and it was found to have a pronounced effect on the interaction of 18-crown-6 with picric acid. The effect of the alkali metal cations, especially Na and K on the complex matrix donor–acceptor surfactant was studied. It is found that the extraction of the insoluble solid NaCl and KCl to the organic phase increased by more than 8-fold in the presence of the complex. The interaction of the alkali metals ions, i.e., Li, Na, K, Cs and Rb with the systems Donor–Acceptor and Donor–Acceptor–Triton were studied. It is found that the stability of the complexes formed between the system CE + Triton + Picric acid and the alkali metals ions depends on the ratio between the crown ether radius and the alkali metal radius.     

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.     

Analogy of the coordination chemistry of alkaline earth metal and lanthanide Ln(2+) ions: the isostructural zoo of mixed metal cages [IM(OtBu)4{Li(thf)}4(OH)] (M=Ca, Sr, Ba, Eu), [MM'6(OPh)8(thf)6] (M=Ca, Sr, Ba, Sm, Eu, M'=Li, Na), and their derivatives with 1,2-dimethoxyethane

As previously shown, alkali and alkaline earth metal iodides in nonaqueous, aprotic solvents behave like transition metal halides, forming cis- and trans-dihalides with various neutral O-donor ligands. These compounds can be used as precursors for the synthesis of new mixed alkali/alkaline earth metal aggregates. We show here that Ln2+ ions form isostructural cluster compounds. Thus, with LiOtBu, 50% of the initial iodide can be replaced in MI2, M=Ca, Sr, Ba, Eu, to generate the mixed-metal alkoxide aggregates [IM(OtBu)4{Li(thf)}4(OH)], for which the M--OH contacts were investigated by theoretical methods. With M'OPh (M'=Li, Na), a new mixed-metal aryloxide cluster type [MM'6(OPh)8(thf)6] is obtained for M=Ca, Sr, Ba, Sm, Eu. Their stability versus DME (DME=1,2-dimethoxyethane) as bidentate ligand is studied.     

Conductance Study of 1 : 1 19-Crown-6 Complexes with Various Mono- and Bivalent Metal Ions in Water

Formation constants (ML) of 1 : 1 19-crown-6 (19C6) complexes with mono- (M+) and bivalent metal ions (M2+) were determined in water at 25 °C by conductometry. The KML value of 19C6 for M+ and M2+ decreases in the order Rb+ K+ > Tl+ > Na+ = Ag+ > Li+ Cs+ and Pb2+ > Ba2+ > Sr2+ > Cd2+ > Ca2+, respectively. The selectivity for the neighboring alkali metal ions in the periodic table is lower for 19C6 than for 18-crown-6 (18C6) except for the case of Rb+ and Cs+. The same is true for the alkaline earth metal ions. Generally, the KML values of 19C6 with M2+ are greater than those with M+. For Na+ and the ions which are smaller in size than Na+ (Li+, Ca2+, Cd2+), the KML value is larger for 19C6 than for 18C6, but the contrary holds for all the other ions of larger sizes than Na+. The limiting ionic molar conductivity (°) of the 19C6–K+ complex in water at 25 °C was determined to be 43. Although 19C6 is larger than 18C6, the 19C6–K+ complex is much more mobile in water than the 18C6–K+ complex.     

Factors governing the metal coordination number in isolated group IA and IIA metal hydrates

Many of the group IA and IIA metal ions, such as Na+, K+, Mg2+, and Ca2+, play crucial roles in biological functions. Previous theoretical studies generally focus on the number of water molecules bound to a particular (as opposed to all) alkali or alkaline earth cations and could not establish a single preferred CN for the heavier alkali and alkaline earth ion-water complexes. Crystal structures of hydrated Na+, K+, and Rb+ also cannot establish the preferred number of inner-shell water molecules bound to these cations. Consequently, it is unclear if the gas-phase CNs of group IA metal hydrates increase with increasing ion size, as observed for the group IIA series from the Cambridge Structural Database, and if the same factors govern the gas-phase CNs of both group IA and IIA ion-water complexes. Thus, in this work, we determine the number of water molecules directly bound to the series of alkali (Li+, Na+, K+, and Rb+) and alkaline earth (Be2+, Mg2+, Ca2+, Sr2+, and Ba2+) metal ions in the gas phase by computing the free energy for forming an isolated metal-aqua complex as a function of the number of water molecules at 298 K. The preferred gas-phase CNs of group IA hydrates appear insensitive to the ion size; they are all 4, except for Rb+, where a CN of 6 seems as likely. In contrast, the preferred gas-phase CNs of the group IIA dications increase with increasing ion size; they are 4 for Be2+, 6 for Mg2+ and Ca2+, and 7 for Sr2+ and Ba2+. An entropic penalty disfavors a gas-phase CN greater than 4 for group IA hydrates, but it does not dictate the gas-phase CNs of group IIA hydrates. Instead, interactions between the metal ion and first-shell water molecules and between first-shell and second-shell water molecules govern the preferred gas-phase CNs of the group IIA metal hydrates.     

Interactions of metal ions with monoaza crown ethers A15C5 and A18C6 carrying dansyl fluorophore as pendant in acetonitrile solution

The influence of metal cations Li(+), Na(+), K(+), Cs(+), Mg(2+), Ca(2+), Sr(2+), Ba(2+), Co(2+), Ni(2+), Cu(2+), Zn(2+), Pb(2+) and Al(3+) on the spectroscopic properties of the dansyl (1-dimethylaminonaphthalene-5-sulfonyl) group covalently linked to monoaza crown ethers 1-aza-15-crown-5 (1,4,7,10,-tetraoxa-13-azacyclopentadecane) (A15C5) and 1-aza-crown-6 (1,4,7,10,13-pentaoxa-16-azacyclooctadecane) (A18C6) was investigated by means of absorption and emission spectrophotometry. Interaction of the alkali metal ions with both fluoroionophores is weak, while alkaline earth metal ions interact strongly causing 50 and 85% quenching of dansyl fluorescence of N-(5-dimethylamine-1-naphthalenesulfonylo)-1,4,7,10,-tetraoxa-13-azacyclopentadecane (A15C5-Dns) and N-(5-dimethylamine-1-naphthalenesulfonylo)-1,4,7,10,13-pentaoxa-16-azacyclooctadecane (A18C6-Dns), respectively. The Cu(2+), Pb(2+) and Al(3+) cations interact very strongly with dansyl chromophore, causing a major change in absorption spectrum of the chromophore and forming non-fluorescent complexes. The Co(2+), Ni(2+), Zn(2+), Mg(2+) cations interact moderately with both fluoroionophores causing quenching of dansyl fluorescence by several percent only.     

香豆素/Betti碱主体合成及其对铷、钡离子的选择性响应(英文)

合成了一个新型香豆素/Betti碱主体化合物1,并对其进行了结构表征。在乙腈/水溶液中进行主体1和碱金属、碱土金属相关离子(Li+,Na+,K+,Rb+,Cs+,Be2+,Mg2+,Ca2+,Sr2+,Ba2+)的相互作用研究时,发现仅Rb+,Ba2+离子对主体1有敏感的紫外光谱及荧光光谱响应,而其它的碱金属、碱土金属离子无敏感性光响应。紫外光谱显示,Rb+,Ba2+离子使主体1产生明显的红移(ε=4.66×102L·(mol·cm)-1,Δ=91nm),肉眼可观察到明显的由浅黄向橙红色的颜色变化,并使主体1的荧光光谱发生一定程度的猝灭。     

A calixarene based fluorescent Sr2+ and Ca2+ probe

A fluorescent probe, PyCalix, which has two pyrene moieties at the lower rim of a calix[4]arene fixed in the cone conformation was synthesized and its complexation behavior with alkali and alkaline earth cations was studied by fluorescence spectrometry. The compound showed intramolecular excimer emission at approximately 480 nm in the fluorescence spectra. Upon complexation with alkaline earth metal cations, a decrease of excimer emission was observed. The decrease of excimer emission was accompanied by an increase of monomer emission of pyrenes at 397 nm. The order of complexation constants of PyCalix with metal ions was Sr(+ approximately Ca2+ > Ba2+ > Mg2+ > K+ > Na+ > Cs+ for all reagents. PyCalix doped polyvinyl chloride (PVC) membrane was fabricated and our results showed that this membrane can be used for selective detection of Sr2+.     

Alkalimetall-Cluster im Zeolith Y Darstellung,Eigenschaften, Reaktionen

Alkali Metal Clusters in Zeolite Y. Preparation, Properties, Reactions Alkali metal clusters (Type AB₃³⁺) were synthesized by reaction of alkali metal A (Li, Na, K, Rb, Cs) with the cations B (alkali, alkaline earth, and rare earth metals) of zeolite Y. The compounds were characterized by UV/VIS spectroscopy, oxidation by carbon oxides and organic halides, and adsorption of gases and polar molecules. The clusters are less reactive than the free alkali metals, the redox potential depends on the alkali metal as well as the cation of zeolite. Chemical interactions with typical ligands and with N₂, Ar, Kr, CO, CO₂, Benzene, and n-Hexane were observed. Reaction with ammonia leads to solvated electrons in zeolite's super-cage, stable up to 240 K.     

A PGSE diffusion and electrophoretic NMR study of Cs+ and Na+ dynamics in aqueous crown ether systems

Multinuclear pulsed gradient spin-echo (PGSE) NMR diffusion and linewidth measurements were used to probe binding and transport in aqueous Na+-15-crown-5, Na+-18-crown-6, Cs+-15-crown-5 and Cs+-18-crown-6 systems. Since direct PGSE observation of many alkali cations is precluded by either low inherent sensitivity or rapid relaxation (or both), the feasibility of proton-detected electrophoretic NMR (ENMR) measurements to complement PGSE data was investigated. ENMR measurements were performed on aqueous Cs+-, Li+-, Na+-, K+-, and Rb+- 18-crown-6 systems. The data analysis is based on a two-site binding model and its corresponding association constants. Cs+ was found to bind considerably more tightly to 18-crown-6 (K=8 M-1) than to 15-crown-5 (K approximately 2 M-1), whereas Na+ had almost equal affinity (K approximately 4.5 M-1) for 15-crown-5 and 18-crown-6. The difficulties encountered in analysing the NMR parameters, methodological limitations and the implied need for more complicated binding models are discussed.     

冠醚配合物的热力学性质的研究 III. 碱金属离子与18C6甲基衍生物配位反应的电导研究

The coordination reaction of Na+, K+, Rb+ and Cs+ with benzo- 15-crown-5, 18-crown-6 and the newly synthesized cyclic polyethers 2, 3-benzo-8, 15-dimethyl-18-crown-6, 2, 3-benzo-8, 11, 15-trimethyl-18-crown-6 in methanol at 25`C has been studied by conductometric titration. The stability constants for the 1:1 coordination compounds were calculated. The marked selectivity of 18-crown-6 toward alkali metal ions was not found in its methyl derivatives. The induction effect of the benzene ring and methyl group on polyether ring reduced the stability of the coordination compounds. In methanol, the stability sequence of te compounds of alkali metal ions with 18-crown-6 was K+>Rb+>Cs+>Na+, that of its dimethyl derivative was K+>Rb+>Na+>Cs+ and that of its trimethyl derivative was K+>Na+>Rb+>Cs+, that is, the methyl substituent had a weaker influence on the stability of Na+ compound than on that of Rb+ or Cs+ compound. In the range of concentration studied, decrease in equivalent conductance is in agreement with the prediction on the basis of the structure of the complexes. The above results may give a clue for modifying the structure of a crown ether for specified selectivity.     

Use of mobile phase 18-crown-6 to improve peak resolution between mono- and divalent metal and amine cations in ion chromatography

It is difficult to quantify NH4+ by ion chromatography in the presence of high concentrations of Na+ due to peak overlap. The Dionex IonPac CS15 column, which contains phosphonate, carboxylate, and 18-crown-6 functional groups, was originally developed to overcome this problem. We have found that the addition of 18-crown-6 to the eluent promotes improved peak resolution between Na+ and NH4+ even at concentrations as high as 60,000 to 1 using this column. Its use also improves the separation of alkali and alkaline earth metal and amine cations. Mobile phase 18-crown-6 increased the retention times of CH3NH3+, NH4+, and K+, and decreased the retention time of Sr2+. The retention times of Li+, Na+, Mg2+, Ca2+, (CH3)2NH2+, and (CH3)3NH+ were not affected. This method makes possible the direct analysis of ammonia from nitrogenase, the enzyme responsible for biological nitrogen fixation. The resolution of the NH4+ peak from the Na+ and Mg2+ peaks improved from zero resolution to values of 6.19 and 5.65, respectively. This technique considerably reduces the analysis time of NH4+ in the presence of high concentrations of Mg2+ and Na+ over traditional indophenol measurements.     

Formation Constants of Complexes of Monovalent Cations with Benzocrown Ethers in Nitromethane

The complexation reactions between the macrocyclic polyethers dibenzo-18-crown-6, benzo-18-crown-6, benzo-15-crown-5 and polyethers bearing a stilbene unit with alkali metal and silver cations have been studied conductometrically in nitromethane. The formation constants of 1 : 1 and 1 : 2 (metal : ligand) complexes were determined and found to decrease with increasing cation diameter. The stability of the stilbene crown – metal cation complexes is lower than for complexes of other investigated crown ethers with analogous cations. There seem to be some effects of double bond-silver ion interactions.     

Synthesis of chromogenic crown ethers and liquid—liquid extraction of alkaline earth metal ions

New crown ether dyes carrying two pendent anionic side-arms were synthesized for the extraction-spectrophotometry of alkaline earth metal ions. In the extraction of alkaline earth metal ions by these dianionic reagents, size recognition by the crown ether ring was more remarkable than in the case of alkali metal ion extraction by a similar type of monoanionic reagents. Dramatic changes in metal selectivity were observed when the nature of the anionic side-arm was changed while the crown ether skeleton was kept the same. The structure/selectivity relationship is discussed in terms of “chelate” and “intramolecular ion-pair” formation. Typically, when the basicity of the pendent anions was relatively high and a six-membered chelate was structurally possible for the pendent anions and the crown-bound metal, the extraction of calcium was favored by up to a factor of 3000 in the ratio of the Ca/Ba extraction constants for reagents of the diaza-18-crown-6 type. In contrast, the reagents which had pendent anions with only poor coordination ability for metal ions seemed to form complexes of the ion-pair type, and calcium ion was 10⁵ times less extractable than barium ion for the same diaza-18-crown-6-skeleton. Strontium ion seemed to be extracted most effectively when the extracted complex assumed properties intermediate between the chelate and intramolecular ion-pair.     

Synthesis of Monoazacryptands and their Excellent Transport Ability Toward Alkali Metal Cations in Comparison with Monoazacrown Ethers

The effects of transport conditions and the structure of monoazacrownethers on their transport ability for alkali metal cations through a bulkliquid membrane are summarized and discussed based on transport dataobtained in our laboratories. To improve the transport ability,monoazacryptands have been prepared. A lipophilic derivative consisting oftwo 18-crown-6 rings and one 20-crown-6 ring can selectively transport K+from a mixture of Na+, K+, Mg2+, and Ca2+ under pH control.