• Analytical Science and Technology
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• v.10 no.1
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• pp.60-65
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• 1997

Solvent extraction of alkali metal and alkaline earth metal cations by mono-crown ether(benzo-15-crown-5) and bis-(crown ether)s(ethylenediamine bis(4'-formyl benzo-15-crown-5)) containing benzo-15-crown-5 moieties were investigated with water-chloroform system at $25^{\circ}C$. The order of the extraction equilibrium constants($K_e$) and the complexation constants($K_c$) for the alkali metal and alkaline earth metal cations with mono-crown ether and bis-(crown ether)s were Ca(II)>Na(I)>Sr(II)>K(I)>Mg(II)>Rb(I) and Sr(II)>Ca(II)>K(I)>Rb(I)>Mg(II)>Na(I) respectively. These results were explained in terms of the size effect of metal cation and electron density effect. Also, the bis-(crown ether)s was found to extract metal cations more effectively than the corresponding mono-crown ether.

• Bulletin of the Korean Chemical Society
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• v.20 no.5
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• pp.556-558
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• 1999

Lead-selective PVC membrane electrodes based on newly synthesized bis(crown ether)s containing 18-crown-6 moiety was prepared using standard PVC membrane composition. In order to monitor lead in environmental samples by lead sensor, especially good selectivity over alkali and alkaline earth metals has to be obtained. Thus, responses of the PVC membrane prepared with new bis(crown ether)s and Fluka ionophore V (crown ether) base to various cations include lead, alkali and alkaline earth metal ions were investigated for their use as a lead sensor. The polymeric liquid membrane based on trans-1 8-crown-6 ether exhibits the best overall potentiometric performances as a lead-selective electrode in terms of a wide linear dynamic range (between 10-6 and 10-2 M, Pb2+), excellent detection limit (less than 10-6 M) and good durability within limited error. The preferences of lead over other cations, such as Ag+, Hg2+, Na+, Ca2+ and even K+ in the aforementioned electrode are much better than the Fluka ionophore V system.

• Bulletin of the Korean Chemical Society
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• v.27 no.11
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• pp.1737-1740
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• 2006

The optimized structures and complexation energies of bis(18-crown-6-ether) analogue (2) of Trgers base (1) with a series of primary alkylbisammonium ions have been calculated by DFT B3LYP/6-31G(d,p) method. The calculated complexation efficiency (-142.84 kcal/mol) of 2 for butane-1,4-diylbisammonium guest is better than twice of the value (-61.40 kcal/mol) for butylammonium ion. The multiple hydrogen-bond abilities for the complexes are described as the function of the length of the alkyl substituents of the bisammonium guests with normal-alkyl chain [$-(CH_2)_{n-}$, n = 4-8]. The longer bisammonium guest shows the stronger hydrogen-bonding characterizations (the distance and the quasi-linear angle of the N-H…O) to the host 2 than the shorter bisammonium ions. These calculated results agree with the experimental data of the complexation of 2 with bisammonium salts ([$NH_3(CH_2)_nNH_3$] $Cl_2$).

• Bulletin of the Korean Chemical Society
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• v.18 no.11
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• pp.1147-1148
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• 1997

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1641-1644
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• 2004

Several [2]- and [3]rotaxanes bearing some functional groups on their wheel components and spacers with different lengths between two ammonium centers on their dumbbell components were prepared in good yields from dibenzo-24-crown-8-ether derivatives and dumbbell-shaped bis(sec-ammonium salt)s having a centrally located disulfide linkage, by utilizing the reversible thiol-disulfide interchange reaction. The shuttling behaviors of the [2]rotaxanes were investigated by $^1H$ NMR by use of the spin polarization transfer-selective inversion recovery technique. It was found that the change in spacer length in the axle resulted in a drastic change in shuttling rate of the [2]rotaxanes, although the introduction of the functional groups to the wheels did not affect the shuttling behavior at all.