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As is well known, a certain ratio of potassium and sodium concentrations is necessary for the normal activity of an organism. Disturbances of the sodium-potassium balance lead to the violations [...], The spectral luminescent properties of terbium(III) complexes of 4-carboxybenzo- 15-crown-5 ([L.sub.1]) and 4-carboxybenzo-18-crown-6 ([L.sub.2]) are studied. The quenching of the luminescence of lanthanide by alkali metal ions is discovered, which is referred to as the formation of mixed Tb(III)-Li-[Na.sup.+] and Tb(III)-[L.sub.2]-[K.sup.+] complexes. The complexes are useful as molecular sensors for the luminescence determination of [Na.sup.+] and [K.sup.+] with the detection limits 1.5 and 25.0 µg/mL. Using the Tb(III)-Li complex, sodium can be determined in the presence of a 1000-fold excess of potassium. The developed procedures are utilized for the determination of KCl in the Kalipoz medication in tablet form and the total sodium salts (NaCl, NaHC[O.sub.3]) in the Trisol solution for infusions. Keywords: luminescence analysis, terbium(III) complexes, 4-carboxybenzocrown ethers DOI: 10.1134/S1061934810121032

On the one hand, interest in the elaboration of ISEs for determining PAA cations is due to the wide application of amine substances in present-day pharmacy (analgetics and anesthetics, antibiotics, [...], The influence of the nature of plasticizer in the membrane of an ion-selective electrode (ISE) on its selectivity to cations of more than 20 physiologically active amines (PAA) is studied. It is found that an increase in the basicity of the plasticizer leads to a sharp increase in the membrane selectivity to PAA cations with lower degrees of the substitution of the salt-forming nitrogen atom, and also to PAA cations with nonionic polar groups capable of forming hydrogen bonds with Lewis bases. PAA cations forming intermolecular hydrogen bonds are an exception. The effect of the nature of the ion exchanger on the selectivity to PAA cations is strongest when plasticizers with low basicity are used; the selectivity of membranes with plasticizers of high basicity does not depend on the nature of the ion exchanger. For ISEs based on the neutral carrier dibenzo-18-crown-6 (DB-18-C-6), the best selectivity to primary amine cations in comparison to secondary and tertiary ones is achieved using plasticizers with low basicity. DOI: 10.1134/S1061934810040118

Methods were developed to convert dipentaerythritol efficiently into di-[OMICRON]-benzylidene, di-[OMICRON]-cyclohexylidene, di-[OMICRON]-l-ethylpropylidene, and di-[OMICRON]-methylene diacetals. The known di-[OMICRON]-benzylidene acetal, considered to be a single isomer, was shown to be close to a statistical mixture of the cis, cis-,cis,trans-, and trans,trans-isomers. Structures were established by a combination of NMR spectroscopy and X-ray crystallography. Reaction of the di-[OMICRON]-benzylidene acetals with benzyl chloride and potassium hydroxide surprisingly gave good to excellent yields of the monobenzyl ethers. An explanation for this observation was advanced. The dibenzyl derivatives of the di-[OMICRON]-benzylidene acetals were formed by reaction of their dianions with benzyl bromide in DMF. Selective reduction of the di-[OMICRON]-benzylidene acetals with triethylsilane and boron trifluoride etherate gave 2',6'-di-[OMICRON]-benzyldipentaerythritol. A crown ether was formed in modest yield (12%) by reaction of the dianion of the di-[OMICRON]-methylene acetal with [alpha],[alpha]'-dibromo-m-xylene in DMF. Key words: dipentaerythritol, pentaerythritol, acetals, dendrimer, selective benzylation, crown ether.

Research describes the synthesis of polymeric/oligomeric and macrocyclic (salophen)Ni(II) complexes from both an achiral biphenol dialdehyde and BINOL dialdehyde. data indicate that these polysalophenes exhibit paramagnetic nonpolar Ni(II) coordination.

Research shows that (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid is an effective NMR chiral solvating agent for protonated amines, amino alcohols, and amino acid esters. Data indicate that ytterbium(III) nitrate causes an upfield shifts in the NMR spectra and enhances the enantiomeric discrimination of the crown ether.

Formation of various solvent clusters under mild source conditions and the loss of charge state information and lack of sensitivity under harsh source conditions are the major problems encountered in elemental electrospray mass spectrometry (ESI-MS). In this work, the use of crown ether complexation as a means of alleviating and solving these problems was evaluated. The crown ether (18-crown-6) was added postcolumn to the flow injection analysis of various metals including alkali, alkaline earth, and transition metals. In most cases, greatly simplified mass spectra that are free from solvent cluster interference could be obtained under suitable in-source collision-induced dissociation conditions. Oxidation state information of singly and doubly charged metals was retained in the metal-crown ether complex ions. Alkali metals were detected by two modes: (i) metal-ether complex ions and (ii) metal ions dissociated from the complexes using in-source collision-induced dissociation. Alkaline earth and transition metals were detected by monitoring the metal-ether complexes. Signal improvements in the range of 5-20 times were achieved for the metals studied. Slight improvements in the dynamic range were also observed.

Electrospray-ionization mass spectrometry using a photoirradiation interface has been successfully applied to the investigation of metal-ion complexation and photoionization of crowned Malachite Green leuconitrile derivatives in solution. The mass spectrometry clearly showed that the Malachite Green derivatives in their electrically neutral forms can complex metal ions with their crown ether moiety. Ionization of the Malachite Green derivatives to their corresponding cationic forms, accompanied by metal-ion repelling from their crown ether moiety, was detected upon UV-light irradiation. A remarkably different photoionization behavior in various solvents, which is difficult to detect by other analytical techniques, was also found by the mass spectrometry.

The hydration of the 18-crown-6 molecule was examined through a rigorous topography mapping of molecular electrostatic potential (MESP). Then, a simple electrostatic model, which considers the electrostatic potential for intermolecular complexation, was employed for determining trends in energetics. Computations using the model were consistent with ab initio calculations, indicating the applicability of MESP topography for investigating the lock-and-key features in a hydration process through cooperative electrostatic effects.

A method for the synthesis of 3-ene-1,5-diyne crown ether was developed based on two different synthetic approaches involving a carbenoid coupling reaction of propargyl bromides. The carbenoid coupling of reaction of propargyl bromide was utilized to simultaneously construct the enediyne moiety and effect a macrocyclization of an acyclic dibromide to a 24-membered crown ether. The resulting 3-ene-1,5-diyne crown ether undergoes Bergman cyclization in DMSO/1,4-cyclohexadiene to produce a known omicron-xylyl crown ether.

Chiral macrocyclic compounds are used in the recognition and separation of amine compounds, important components of protein synthesis, enzyme systems, and other biomolecular interactions. Chiral macrocycles form stable complexes with enantiomers without significant interaction and repel other enantiomeric complexes. Low conformational flexibility promotes selective enantiomeric recognition.

A novel method of synthesizing related cage molecules and macrocyclophanes was developed through the use of the same technique for synthesizing TTF vinylogues. The design utilized bis(1,4-dithiafulvenes) as primary substrates. The intermediate underwent the same redox behavior as with 1,4-diathiafulvenes.

The effect of selected crown ethers on the uptake of alkaline earth cations by sulfonic acid and diphosphonic acid-based cation-exchange resins from hydrochloric acid media is examined. The effect observed is shown to vary with the hydrophobicity of the crown ether. Water-soluble crown ethers enhance the sorption of certain cations, thereby improving the selectivity of the resin for other alkaline earths over calcium ion, an apparent result of a synergistic interaction between crown ether present in the resin phase and the ionic functional groups of the resin. In the presence of more hydrophobic crown ethers, a decrease in cation sorption is often observed, a result of the exclusion of the crown ether from the resin phase and the formation of cation - crown complexes in the solution phase. The result can be a reversal of the selectivity sequence ordinarily exhibited by the resin.

1H nuclear magnetic resonance titration method was utilized to examine the selective binding constants for Sc3+, Lu3+, Y3+, and La3+. It was shown that the binding of a metal ion was initially mediated by an alcoholysis reaction between the macrocycle and metal ion resulting in the formation of a M(H2L)X2 complex. A sheet structure with solvent byproduct was formed using AgCF3-SO3 in benzene. It was also indicated that the counterions had a direct effect on the coordination network topology.

A novel method of synthesizing 4,6,7-substituted quinoline-5,8-quinones through the use 2-lithio-N-BOC-1,4-dihydropyridines with cyclobutenediones was described. The procedure featured the utilization of thermolysis of 1,2-adduct with concomitant oxidation of the resulting dihydroquinoline hydroquinone in acetic acid. Thermolysis induced the production of ring-fused pyridones through allowing the ketene modification by the electron-rich nitrogen atom.

Copper(II) oxidation procedure was utilized to cyclize a,c-biladienes containing 1- and/or 19-(para-tolylmethyl) substituents yielding numerous products wherein 1- or 19-substituents had modified positions in the tetrapyrrole macrocycle. a,c-Biladiene coordinates rendered copper(II) 1-(para-tolylmethyl)-20-para-tolyl macrocyclic compounds, copper(II) 2-methylidenechlorin and copper(II) porphyrins upon copper(II)-assisted cyclization. para-Tolyl-methyl group displayed more stable contributions of methylene both as macrocyclic bridging carbon and interpyrrolic carbon atom.

The effect of charge redistribution in tetraethylammonium salt intermediates was investigated through the utilization of para-methylbenzyl bromide as electron acceptor. The regioisomer distribution in the alkylation of a calix compound was found to be similar to the pathway of active monoionic reaction. It was shown that the product distribution was determined by charge redistribution in the substrates and the protonation/deprotonation balance.

The electron density topology in a non-centrosymmetric transition metal macrocyclic complex was analyzed. A multiple model was fitted to high resolution x-ray diffraction data. It was found that the redistribution of the electron density reduces the charge on the metal. The characteristics of of the charge density on the metal were dominated by four diffuse lobes which pointed at the ligating oxygen atoms.

The synthesis of a novel macrocyclic N3S2 ligand, 4,10-dithia-1,7,13-triazabicyclo[11.3.3]nonadecane was developed through the utilization of (N,N'-bis(2-mercapttoethyl)-1,5-diazacyclooctane)nickel(II) template reaction. The macrocyclic compound was insoluble in Et2O, CH3CN, and hydrocarbon solvents. Studies indicated that a solution of the ligand exposed to low concentrations of RhIII formed a cationic complex.

A pentachloroaquaplatinate complex with an [H13O6]+ cation in a cage with three crown ether molecules was synthesized from the reaction of crown ether 18-crown-6 with H2[PtCl6].6 H2O. The [H13O6][PtCl5(H4O2)].2(18-cr-6) crown ether complex exhibited a five-membered chain of water molecules containing the [H13O6]+ ions. Furthermore, the water molecules of the crown ether complex of pentachloroaquaplatinic acid acted as electron donors and acceptors that mediate the formation of a dihydrated triaquaoxonium ion.

A method for the synthesis of 3-ene-1,5-diyne crown ether was developed based on two different synthetic approaches involving a carbenoid coupling reaction of propargyl bromides. The carbenoid coupling of reaction of propargyl bromide was utilized to simultaneously construct the enediyne moiety and effect a macrocyclization of an acyclic dibromide to a 24-membered crown ether. The resulting 3-ene-1,5-diyne crown ether undergoes Bergman cyclization in DMSO/1,4-cyclohexadiene to produce a known omicron-xylyl crown ether.

Infrared multiphoton photodissociation (IRMPD) is combined with stored wave form inverse Fourier transforms (SWIFT) to effect dissociation and ion ejection in a quadrupole ion trap mass spectrometer. The application of IRMPD to the structural characterization of biochemical ions generated by chemical ionization and electrospray ionization and the feasibility of utilizing infrared photons for the activation of laser-desorbed metal ion - crown ether complexes was examined. The effect of helium pressure on the dissociation efficiency and relative dissociation rate constants for systems with well-known thermochemistry was evaluated. The helium pressure is not detrimental to the IRMPD experiment when nominal pressures lower than 2 x [10.sup.-5] Torr are used. At pressures close to nominally 8 x [10.sup.-5] Torr of helium, collisonal deactivation dominates. Results show conventional CAD is a more selective dissociation technique; however, the amount of fragment ion information generated depends highly on the [q.sub.Z] value. IRMPD, on the other hand, is independent of the value of [q.sub.Z] such that low rf storage values can be utilized during the irradiation period. Thus, under these conditions, informative lower mass fragment ions are trapped and detected. A larger number of structurally informative fragments is generated upon irradiation with infrared photons relative to the CAD method because of the further excitation of primary fragment ions upon photoabsorption. SWIFT wave forms are successfully utilized to determine the extent of excitation of primary fragment ions as well as prove/disprove dissociation pathways of a variety of ions such as macrolide antibiotics and hydrogen-bonded complexes.

The design, synthesis and characterization of the simplest tapered monodendrons with crown ethers that self-assemble into cylindrical or rod-like supramolecular dendrimers, displaying a thermotropic phi(sub h) liquid crystalline phase solely via the fluorophobic effect, are described. It is the first structural comparison of the two supramolecular systems assembled either by ion-mediated processes or by the fluorophobic effect. Findings show the remarkable potential of the fluorophobic effect in supramolecular chemistry.

The adduct formation of ruthenium complexes with 18C6 is dependent on the valence of its metallic center. An evaluation of the process of ruthenium adduct formation indicated several factors that affect redox potential. Adduct formation is affected by the number of coordinating ammine ligands to ruthenium. The pi-electron acceptability of a ligand that does not interact with 18C6 and the flexibility of the crown ether ring also change the redox potential.

The derivatized crown thioethers 3,6,9,12,15,18-hexathianonadecanol (19-aneS6-OH) and 3,6,9,13,16,19-hexathiacycloicosanol (20-aneS6-OH) are prepared by (1 + 1) cyclization and used as ligands for synthesizing silver(I) complexes. The silver complex cations (Ag(19-aneS6-OH))+ and (Ag(20-aneS6-OH))+ reside in a distorted tetrahedral coordination geometry. The complex cations have identical solution structures but different solid structures. Stability constants for the silver complexes in methanol are estimated.

Metal-free and dihydroxysilicon derivatives of liquid crystalline tetrakis(4',5'-bisdecoxy-benzo-18-crown-6)phthalocyanine are prepared which is liquid crystalline and in chloroform accumulate to yield a gel. In the gel, the network fibers are made up of parallel strands of supermolecules and formed through self-assembly of about 10 to the fourth power molecules. The strands are characterized as molecular cables constituting a central electron wire, four ion channels and an encompassing insulating hydrocarbon mantle.

A reaction between 2,6-bis({tosyloxy}methyl)pyridine and THP-protected 4-hydroxy-2,6-{bis(tosyloxy)methyl}pyridine with 3,9-dioxa-6-azaundecane-1,11-diol in strong base results in the formation of pyridinoazacrowns. Phenol-substituted pyridonoaza-18-crown-6-ligands exhibit high stereoselectivity and form complexes with different metal cations. Sixteen ligands possessing pyridine rings have been synthesized. These diazocrowns have high selectivities for Mg2+, K+, Ba2+, Cu2+.

Research into the kinetics and mechanism of sodium cation complexation by 5,11,17,23-tetra-p-tert-butyl-25,26,27,28-tetramethoxy-calix(4)arene shows that this compound acts like an intermediate between crown ethers and cryptands. Measurements were made by NMR spectrometer in a mixture of acetonitrile and chloroform, for which kinetic parameters have been predetermined. The calixarene shows rates of dissociation similar to those of crown ethers, and rates of formation typical for cryptands.

Reductive intramolecular coupling of aromatic diimines is used for the synthesis of nitrogen-containing macrocycles. Intramolecular coupling of bis(imino ethers) by electroreduction and chemical reduction with zinc powder leads to the formation of 1,4-diazacrown ethers, in which intramolecular hydrogen bond is formed between hydrogen and oxygen atoms of diiminium salts. The method involving chemical reduction with zinc is effective due to template effect of zinc ion.

Investigations into the mechanistic aspects of the stereospecific interaction of the four optical isomers of aminoindanol on a silica based crown ether column were performed. The nature and concentration of the mobile phase's counteranion affected the hydrophobic interaction but had little effect on the inclusion interaction. Minimal changes in the separation factor of the enantiomers were observed in the pH range of 1-5.2, but a minimum in the capacity factor was observed at pH 3.75. Van't Hoff plots indicated a high entropy and a positive enthalpy at pH 5.2, while a lower entropy and a negative enthalpy were observed at and below pH 3.75. Hill plots indicated that there were more active binding sites at pH 3.0 as compared to pH 1.0 and that the binding ratio of aminoindanol to active sites was also greater. Apparently at higher pH values, as the silica becomes deprotonated, there is an additional electrostatic interaction between the protonated aminoindanol and the deprotonated silica sites.

Spectroscopic studies reveal that both cation and anion hydrations influence the stability of second-sphere coordination of ferrioxamine B (FeHDFB+) with a crown ether (CE) in wet chloroform. The host-guest supramolecular assembly FeHDFB+,CE,X- (1) is formed by the intercalation of CE with the ion pair FeHDFB+,X-. This intercalation and experimental data reveal the differences between the mechanisms of distribution process and chloroform extraction process. The host-guest interactions and the aqueous/organic phase extractions can be optimized using appropriate (cation, anion) combinations for the crown ether.

A single-step reaction between methyl 3,5-dihydroxybenzoate and oligo(ethylene glycol) dichlorides produces bis(5-carbomethoxy-1,3-phenylene)-(3x+2)-crown-x compounds. X-ray crystallography enables the determination of the structures of these compounds. 1H NMR spectroscopy helps analyze the thermal stabilities of these compounds and the ability of the bis(m-phenylene)-32-crown-10 derivatives to form complexes with methyl viologen bis(hexafluorophosphate).

Synthesis of bis-anthracenediyl macrotricyclic receptor helps analyze the relation of cation complexation with fluorescence emission. Two anthracene chromophore-containing flexible spaces connect two diazacrown ether moieties in the macrocycle. Metal cations influence the dual fluorescence emission of the molecule. Spectroscopic studies reveal the influence of complexed cation on the optical properties and X-ray studies demonstrate the presence of two Rb(+) cations within the hydrophilic N2O4 parts. Mono- and binuclear Rb complexes exhibit noncooperative behavior and high stability in solution.

Cyclic voltammetric studies of the redox potentials of 22 ferrocene nitrogen compounds help analyze redox-switched bonding of cations to ferrocene crown ethers. X-ray studies help characterize diprotonated, methylated and dimethylated ferrocene compounds. Structure and redox potentials reveal a linear relationship between inverse ion-nitrogen separation and redox potential shift that helps determine the structure of protonated isomers of ferrocenes.

The molecular recognition of the terminal group of ferrioxamine B and its Al(III), Ga(III), Fe(III) and In(III) complexes by the crown ether dicyclohexano-18-crown-6 involves host-guest complex formation. A chloroform extraction reaction characterizes the molecular recognition and analyzes the influence of alkyl and hydroxamate substituent groups on the formation of host-guest complex.

An 18-crown-6 in 1,2-dichloroethane reacted with zinc chloride in diethyl ether to synthesize two crystalline complexes. The first complex was formed when the crown ether fused with the hydrated zinc species when aquo ligands interacted with the hydrogen bonds. Zinc-to-crown ether coordination characterized the second complex, which comprised zinc species that were not fully encapsulated.

A chromatographic method based on the ion-exchange resin phase complexation of crown ethers with a countercation is proposed to determine the solution phase complexation constants, which can be extracted from dependences of the retention of crown ethers on the metal ion concentration in a mobile phase. A single experiment also allows the rough estimation of complexation constants as long as 1:1 stoichiometry is maintained for the resin phase complexation. The column design for the precise evaluation of the complexation is also discussed using nonlinear regression.

Cubic F23 (Rb18C6)4-((MnCl4)(MCl4)(x))(TlCl4)2 complexes are obtained by competitive complexation of MCl4(2-) ligands. The study of the luminescence decay dynamics of trapped species indicates that the sensitivity of the cubic lattice is influenced by the thermodynamic stability of the ions. Facile donor-donor energy transfer is caused by the large amount of multipolar interactions. Exciton trapping in water molecules terminates the energy migration in the cubic lattice.

Macrocyclic compounds consisting of pyridine have synthesized 7-methyl-3,7,11, 17-tetraazabicyclo(9.3.1)pentadeca-1(15),11,13-triene, 3,7,10, 16-tetraazatricyclo(10.3.1)hexadeca-1(16),12,14-triene and 3,7,11, 17-tetraazabicyclo-(11.3.1)heptadeca-1(17),13,15-triene. A pair of highly basic and the other two highly acidic nitrogen atoms result from the protonation reactions of these ligands.

An electride and six new alkalides consisting of mixed sandwich complexes of alkali metal cations with 18-crown-6 (18C6), 15-crown-5 (15C5) and 12-crown-4 (12C4), are synthesized. Thermodynamic stability of the mixed sandwich compounds as against the 'parent' compounds which have only one kind of complexant was verified by establishing the crystal structures of K+(18C6)(12C4)Na-, K+(18C6)(12C4)K-, K+(18C6)(12C4)K-.18C6, Rb+(18C6)(12C4)Na- and Rb+(18C6)(12C4)Rb-.

The effects of host (crown ether) size and structure and guest (ruthenium complex) oxidation state and primary ligand environment on binding strength were reported. It was found that binding increases with increased size and flexibility of the crown ether. It also increases with increased availability of ammine ligands, higher oxidation state and increased Lewis acidity of the guest. Small amounts of crown ether can also have substantial effects upon metal-ligand and metal-metal charge-transfer interactions.

The synthesis of intercalates of MPS3 (M = Mn, Cd, Zn) materials containing sodium and potassium cations and crown ethers and their study by 23Na nuclear magnetic resonance spectroscopy were reported. A comparison of the coordination chemistry of the new organometallic crown ether complex cation (CpRu-(eta6-benzo-15-crown-5))+ (Cp = eta5-C5H5) with Na+ in solution and after intercalation was also reported.

The preparation of three ferrocene-crown derivatives along with their amide precursors was reported. Comparison of these structures shows that the iron atom of ferrocene is a donor ligand for Ag+ but not Na+. The ferrocenyldimethyl(2.2)cryptand exhibits redox-switching properties in aqueous solution. It was shown that complexation occurs within the cavity and not on the periphery as is the case with certain amidic relatives of the present structure.

The alpha- and beta-secondary isotope effects on the peracid epoxidations were probed through the use of prepared alkenes 1-phenyl-3-methyl-2-butene and 1-phenyl-3-(methyl-d3)-2-butene-4,4,4-d3 as catalytic intermediates. It was found that the nature of the transition state governing the reaction was consonant with the oxygen transfer in a nonpolar transition state. In a nonpolar transition state, a small inverse secondary isotope effect is the result of the shift of the steric interactions from a less crowded to a more crowded state.

This report demonstrates that crown ethers can be modified with thiol functionalities and anchored to silver surfaces without loss of activity. Once attached the responsivity of the crown can be examined with surface-enhanced Raman spectroscopy. The crown examined was a diaminodibenzo-18-crown-6 coupled to mercaptonicotinic acid with DCC to form an amide. We found that the derivitized diaminodibenzo-18-crown-6 responded to alkali chlorides. The K(sub formation) and selectivity were determined and followed a trend similar to that observed in aqueous solutions. An ionic strength test indicated that the phenomenon was due to the cation and not the anion. However, a larger K(sub formation) was observed with SCN-.

Competitive liquid membrane transport evaluation of the complexing abilities of hydroxymethyl and dodecylphosphoric acid-armed crown ethers revealed an enhanced transport rate and variations in cation selectivity. The change in selectivity is due to the presence of dodecylphosphoric acid group on the crown ring. 13C-NMR titration studies on alkali metal complexes revealed significant chemical shift changes to downfield of the methylene carbons.

The novel reaction of an axis molecule containing a kerosene moiety, which is activated by an electrochemical stimulus and forms a pseudorotaxane with a crown ether, is reported. The reaction takes place by electrochemical oxidation and is completed rapidly in the presence of a suitable hydrogen atom source.

Electrostatic potential in the vicinity of the surface of a cation-exchange resin has been evaluated by modeling chromatographic retention. Binary mixtures of [K.sup.+] and its crown ether complex in methanol are used as mobile phases, and two types of solutes, that is, cationic and crown ether probes, have been examined. The cationic probes show the sigmoidal retention changes with increasing concentration of a crown ether incorporated into the mobile phase, whereas crown ether probes give retention maximums. The model derived from the Poisson-Boltzmann theory well explains these specific changes in probe retention and gives the electrostatic potential at the closest approach of each probe molecule. The closest approaches for probe molecules correlate well with their molecular sizes. In addition, changes in retention of cationic probes also correlate well with the electrostatic potential changes at the closest approaches of probe molecules, indicating that simple sensing of the electrostatic potential is feasible using probe retention. The reduction of crown ether complexation occurs in the vicinity of the cation-exchange resin surface and causes the specific retention behaviors of crown ether probes in the mobile-phase systems composed of [K.sup.+] and its complex with a modifier crown ether.

Reaction between the cis-configurated bis-ammonium triflates and equivalent amount of the chiral crown leads to the formation of two diastereomeric 1:1 complexes. The complexes confirm the presence enantiotopic group recognition and enantioselective molecular recognition. The reacting meso-compound with enantiotopic NH(super +)(sub 3) groups is a racemic mixture of rapidly interconverting enantiomeric chair conformers. The chiral host selectively binds to either of the two enantiotopic groups in the single and same guest meso-compound.