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1.
The effects of Na+, K+ and Li+ cations on the fluorescence spectra of benzo[15]crown-5, benzo[18]crown-6 and dibenzo[18]crown-6 were investigated in acetonitrile. The alkali cation role observed was usually the complexation-enhanced quenching fluorescence effect (CEQF) in acetonitrile due to the increased fluorescence quenching rate of the complexed fluoroionophore. The association constants for 1 :1 stoichiometry InK a have been obtained using the relationship 1/K a[L 0] = (1 –P)2/P. It was shown that the preferential interaction rule of compatibility of cationic radii and macrocyclic ring size is in excellent agreement with the association constants obtained by fluorescence spectroscopy. The order of InK a found for benzo[15]crown-5 complexation was Li+ > Na+ > K+ and K+ > Na+ > Li+ for benzo[18]crown-6 in acetonitrile.Presented at the Sixth International Seminar on Inclusion Compounds, Istanbul, Turkey, 27–31 August, 1995.  相似文献   

2.
The complexing (in CHCl3) and extracting abilities of 18-crown-6 type compounds (1–15) were measured with Li, Na, K and NH4 cations. The substituents on the sugar part affected these properties significantly (K a=103–107). Some substituents, like acetyloxy groups (3) decreased whereas others, like tosyloxy groups (10, 11) significantly increased the complexing ability and thus changed the selectivity. The compound with four tosyloxy groups (11) shows an excellent picrate salt extracting ability in a CH2Cl2-water system.  相似文献   

3.
3‐Phenyl‐ and 3‐(p‐methoxyphenyl)‐7,8‐dihydroxy and ‐6,7‐dihydroxychromenones were prepared from ethyl 3‐oxo‐2‐phenylpropanoate, ethyl 3‐oxo‐2‐(4‐methoxyphenyl)‐propanoate and the trihydroxy benzenes in H2SO4. 3‐Aryl‐7,8‐ and 3‐aryl‐6,7‐dihydroxy‐2H‐chromenones reacted with the bis‐dihalides of poly‐glycols in DMF/MeCO3 to afford 12‐Crown‐4, 15‐Crown‐4 and 18‐Crown‐6‐chromenones. The products were identified with IR, 1H NMR, low and high resolution mass spectroscopy and elemental analysis. Some 1:1 cation association constants, Kb, of the 3‐phenyl chromenone crown ethers with Li+, Na+, K+ and Rb+ cations were studied by steady state emission fluorescence spectroscopy; Kb chromenone‐crown complexes displayed crown ether‐cation binding selectivity rules properly in acetonitrile.  相似文献   

4.
Polymers that have crown ether groups as cation binding sites and cinnamic acid ester groups as photodimerizable groups were prepared by the cationic polymerizations of 2-vinyloxyethyl 4′-(2,3-benzo-1,4,7,10,13-pentaoxa-2-cyclopentadecene)acrylate and 2-vinyloxyethyl 4′-(2,3-benzo-1,4,7,10,13,16-hexaoxa-2-cyclooctadecene)acrylate. When irradiated with ultraviolet (UV) light the cinnamic acid ester groups of the polymers caused dimerization in dilute solution without the formation of insoluble materials. The irradiation was carried out in a dioxane solution and an aqueous solution in the presence and absence of salts. The effect of phototransformation of polymers on the cation binding properties was investigated by a method of picrate salts extraction. The binding ability of the phototransformed polymers for alkali and alkaline earth metal cations was higher than that of the native polymer. Furthermore the cation binding ability of the phototransformed polymers was less sensitive to temperature than that of the native polymer. The effect of the degree of photodimerization of the polymers and the concentration of KCl that exists during irradiation on the cation binding ability was also investigated.  相似文献   

5.
Kubo K  Sakaguchi S  Sakurai T 《Talanta》1999,49(4):735-744
Armed crown ethers (1-4) bonding through an amine, amide, ether, or ester linkage to naphthyl group were found to display unique photophysical properties in the presence of guest salts. Complexation of PET fluoroionophores (1a and 1b) with Zn(2+) increased the fluorescence intensities of the host by a factor of 2.4 and 2.7, respectively. (1)H and (13)C NMR analyses of this complexation behavior of 1a revealed that Zn(2+) strongly coordinates with the armed crown nitrogen to cause a dramatic decrease in an intramolecular charge-transfer character. The armed crowns (2 and 3), bonding through an ether or ester linkage to a naphthalene, gave fluorescence quenching with guest thiocyanates. While the amide derivative (4) exhibited high Ba(2+) fluorescence selectivity and in the presence of this cation the host fluorescence intensity was by a factor of 3.69.  相似文献   

6.
We report a study on the absorptive and emissive properties of 9‐acridinones, 9‐thioacridinones and 9‐aminoacridines including six crown ether derivatives. The effect of solvents and of the addition of cations (Na+, K+, Ca2+ and Mg2+) on these properties has been studied. The absorption of the crown ether derivative of 9‐thioacridinone is sensitive to solvents while the fluorescence of crown ethers derived from 9‐aminoacridines shows some specificity towards cations. Empirical modeling was used to discuss the emission characteristics of these compounds.  相似文献   

7.
胡靖  郭志全  童林荟 《化学学报》1984,42(3):246-252
本文报道六种非手性芳香冠醚,即苯并-15-c-5,苯并-18-c-6,4-叔丁基苯并-15-c-5,二苯并-18-c-6,二苯并-24-c-8,4,4’二叔丁基二苯并-30-c-10,在3:2水-甲醇体系中同β-环糊精配位时的紫外光谱及诱导出的圆二色性谱。有趣的是,这些冠醚的邻苯二酚基生色团的~1A_1←~1A_1及~1B_2←~1A_1跃迁区的每一个谱带区均诱导出负正交替的圆二色性,经用Job连续变量法及摩尔比法确定系有两种配合物生成,一种是2:1 β-环糊精-冠醚配合物,另一种是1:2 β-环糊精-冠醚配合物。应用Shimizu等的理论结果,确定了含邻苯二酚基生色团的冠醚在β-环糊精空腔中的取向及其包结形态。就2:1配合物而言,本质上是一种亲脂相互作用,它遵循环糊精包结物的一般规律。对于1:2的β-环糊精-冠醚配合物,不存在β-环糊精空腔对冠醚的邻苯二酚基生色团的包结作用,所以推断其结构可能是,二个冠醚分子分别从β-环糊精圆筒的两端将环糊精分子包结起来,彼此间的作用是一种亲水相互作用。  相似文献   

8.
An STO/3G study of the binding of alkali cations to dimethylether is performed. The study of the conformation of free 12-crown-4 and of its Li+ complex indicates that a modification of the conformation of the polyether accompanies the complexation.  相似文献   

9.
The collision-activated dissociation (CAD) mass spectra for a series of crown ethers, perfluoro crown ethers, cryptands and several dicyclohexano substituted crown ethers are reported. The CAD spectra were acquired with a triple quadrupole mass spectrometer, and in some cases spectra were recorded as a function of collision energy. In general, the protonated crown ethers dissociate via a series of losses of C2H4O units. The perfluoro crown ethers dissociate predominantly via losses of C2F4O units. The dicyclohexano ethers fragment in analogous ways in conjunction with cleavage of the cyclohexano rings. CAD spectra are also reported for acyclic ether systems.  相似文献   

10.
Chiral crown ethers 1 and 5 are useful enantiomeric discriminating agents in 1H NMR spectroscopy for neutral and protonated primary amines, amino acids, and amino alcohols. The presence of the carboxylic acid groups in 1 and 5 provide sites at which ytterbium(III) can bind. Adding ytterbium(III) nitrate to crown–substrate mixtures in methanol-d4 causes shifts in the spectra of substrates and often enhances the chiral discrimination in the 1H NMR spectrum. The enhancement in enantiomeric discrimination that occurs in the presence of ytterbium(III) allows lower concentrations of the crown ether to be used in chiral recognition studies. Several amide derivatives of 1 were prepared and evaluated as chiral NMR discriminating agents, although except for 1e, these were less effective than 1.  相似文献   

11.
12.
13.
14.
15.
The effects of alkali metal complexation on the fluorescence properties of two crown ethers (a podand and a coronand) were investigated. Metal ion binding leads to changes in fluorescence intensity along with slight shifts in the emission maxima. This is attributed to a rigidization of the fluorophore and an interaction of the metal ion with non-bonding electrons of the crown ethers. The effects on the spectra are more pronounced in fluorescence than in absorption.Fluorescence titration with metal ions provides a simple and sensitive means for the determination of complexation constants, which were found to be highly dependent upon the water content of the methanol solution. Halide counterions, in particular iodide, act as dynamic fluorescence quenchers withStern-Volmer constants that are different for the sodium and potassium complexes, respectively.
Die Effekte der Komplexierung von Alkalimetallionen auf die Fluoreszenzeigenschaften von Kronenethern
Zusammenfassung Die Effekte der Komplexierung von Alkalimetallionen auf die Fluoreszenzeigenschaften zweier Kronenether (eines Podanden und eines Coronanden) wurden untersucht. Die Bindung des Metallions fürt zu Veränderungen in der Fluoreszenzintensität und zu Verschiebungen in den Emissionsmaxima. Dies wird einer gesteigerten Starrheit des Fluorophors und einer Wechselwirkung des Metallions mit nichtbindenden Elektronen des Kronenethers zugeschrieben. Die Auswirkungen auf die Spektren sind in der Fluoreszenz ausgeprägter als in der Absorption.Fluoreszenztitrationen mit Metallionen bieten eine einfache und empfindliche Möglichkeit zur Bestimmung von Komplexkonstanten, welche stark vom Wassergehalt der methanolischen Lösung abhängig befunden werden. Halogenidgegenionen, insbesonders Iodid, wirken als dynamische Fluoreszenzlöscher und weisenStern-Volmer-Konstanten auf, welche für die Natrium- bzw. Kalium-Komplexe verschieden sind.
  相似文献   

16.
The easily accessible and multi-functionalized 5,8-dimethoxy-6,7-dihydroxy methyl-1,4-dihydro-1,4-methanonaphthalene (1) has been utilized as the basic building material to synthesize the symmetric bis-methanonaphthalene-fused crown ethers 14a-d (BMN-16-crown-4, BMN-22-crown-6, BMN-28-crown-8, and BMN-34-crown-10), that are constructed based on the connection between the α,β-bis-benzylic carbon atoms of diol 1 and oligoethylene glycols (9a-d) via two synthetic routes keyed upon the method of Williamson ether synthesis.  相似文献   

17.
The reactions between alkali metal ions and crown ethers, aza crown ethers, and cryptands in propylene carbonate were studied by potentiometric and calorimetric titrations. The most stable complexes formed by macrocyclic and macrobicyclic ligands are when the ligand and cation dimensions are comparable. On comparing the complex stabilities of crown ethers and aza crown ethers of the same size, crown ethers were, on the whole, found to form the most stable complexes, with the exception of the lithium cation. Enthalpic factors are responsible. Substitution of the amino group protons of the aza crown ethers by benzyl groups leads to a high increase in values of the reaction enthalpy. This effect is partly compensated by entropic contributions. The bulky benzyl groups reduce the ligand solvent interactions and induce a ligand conformation with the lone pair of electrons from the nitrogen donor atoms which are more or less directed inside the cavity. The thermodynamic data for the transfer from methanol to propylene carbonate indicate that the ligands containing nitrogen show specific interactions with methanol.This paper is dedicated to Professor H. Strehlow on the occasion of his 70th birthday.  相似文献   

18.
In contrast to aluminum alkyls, alkyl aluminum halides such as EtAlCl2 react with crown ethers to form cation-anion pairs which exhibit the liquid clathrate effect. Specifically, [12-C-4·AlCl2][AlCl3Et] and [18-C-6·AlCl2][AlCl3Et] have been isolated and characterized by X-ray diffraction techniques. The cations show aluminum in an octahedral environment made up of four of the oxygen atoms from the crown and two chlorine atoms. The 12-C-4 derivative crystallizes in the monoclinic space group P21/c with cell constants of a=7.497(4), b=22.121(8), c=12.339(5) Å, =94.99(3)o, and Z=4 for =1.43 g cm–3. Least-squares refinement based on 1413 observed reflections led to a final conventional R value of 0.093. The 18-C-6 complex belongs to the triclinic space group P1 with a=8.414(4), b=12.193(6), c=12.394(6) Å, =73.14(4), =86.07(4), =81.52(4)o, and Z=2 for =1.45 g cm–3. Refinement based on 2605 observed reflections led to R=0.063. The complex aluminum-containing species are related to a class of compounds called aluminoxanes.  相似文献   

19.
Dibenzotetraaza (DBTA) crown ethers possess two o-phenylenediamine moieties. They are homologues of dibenzo crown ether phase-transfer catalysts and were prepared from the condensation of benzimidazoles with oligo(ethyleneglycol) dichlorides and oligo(ethyleneglycol) ditosylates. Compounds with ring sizes ranging from 18-crown-6 to 42-crown-14 were prepared. In addition, various altered benzimidizoles were used to produce DBTA crown ethers with modified substituents and ether bridges, as well as benzimidazolidine crown ethers. The synthetic approach presented here proved to be a convenient route to a new family of crown ethers with overall yields of up to 48% based on the benzimidazole. Yields for the ring-closing step were generally high, ranging from 51% to 94%, without the need for high-dilution conditions. Reaction of the DBTA crown ethers with alkyl and benzyl halides was found to be a facile way to obtain the corresponding tetra(N-organyl) compounds. Picrate extraction studies were carried out to determine phase-transfer catalytic capabilities. Extraction efficiencies for alkali-metal ions were lower than those for dibenzo-18-crown-6. Efficiencies were higher for other metal ions, with some selectivity for Pb(2+). Tetra(N-methyl) DBTA-18-crown-6 generally exhibited higher extraction efficiencies than its N-H analogue, but the selectivity was lower.  相似文献   

20.
Tuncer H  Erk C 《Talanta》2005,65(3):819-823
The steady-state fluorescence spectra of cation complexes of fluorophore macrocyclic ethers have been studied for the estimation of 1:1 association constants, and perchlorate salts of Li+, Na+, K+ Rb+ and Pb2+ complexing with dibenzo[23]crown-9, dibenzo[26]crown-10, and sym-dibenzo[26]crown-10, were investigated. The fluorescence emission maximum of the free and the various ligand/cation mixtures of complexed crown ethers were measured at room temperature in AN. The concentrations of chromophore crown ether were obtained from nonlinear calibration plots. The 1:1 stoichiometry of association constants (Kass) were calculated using the equation, 1/Kass [Lo] = (1 − nP)n(1 − m)m/P with linear best fit of plots depending on 1/[Lo] where P = PC/[1 + (m − 1)PC] and PC is the mole fraction of n/m ratio of the complexed ligand. The association constants of cations, Kass, displayed the cation selectivities depending on the cation radii and the macrocyclic ether size, and Pb+ was found to give the strongest association with such crown ethers.  相似文献   

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