The Viscosity Coefficients of 18-Crown-6–Alkali Metal-ion Complexes

Cold Spectroscopy of Metal Ion-Crown Ether Complexes in the Gas Phase

Ultraviolet photodepletion spectroscopy of dibenzo-18-crown-6-ether complexes with alkali metal cations.

Ultraviolet photodepletion spectra of dibenzo-18-crown-6-ether complexes with alkali metal cations (M(+)-DB18C6, M = Cs, Rb, K, Na, and Li) were obtained in the gas phase using electrospray ionization quadrupole ion-trap reflectron time-of-flight mass spectrometry. The spectra exhibited a few distinct absorption bands in the wavenumber region of 35 450-37 800 cm(-1). The lowest-energy band was ...

Nuclear magnetic resonance and ab initio theoretical studies of 18-crown-6, benzo- and dibenzo-18-crown-6 and their alkali-metal complexes

The formation of alkali-metal ion complexes with the crown ethers, 18-crown-6(18c6), benzo-18c6 and dibenzo-18c6 has been investigated. Theoretical studies of structural changes on complexation, binding energies and changes in electron distribution have been carried out using ab initio quantum theoretical methods. A complementary study of the NMR chemical shifts and coupling constants has also ...

Influence of Metal Ion Complexation on the Acid Dissociation of 4'-Carboxybenzo-24-Crown-8 in an Ethanol-Water Mixture

A spectrophotometric method was used to determine the acidity constant of 4'-carboxybenzo-24-crown-8 in 52% (w/w) ethanol-water mixture. The acid dissociation constant, Ka, was found to increase in the presence of Na+, K+, Rb+, Cs+ and Tl+ ions. The formation constants of the resulting 1:1 complexes between the carboxycrown a...

EXTRACTION-SPECTROPHOTOMETRIC DETERMINATION OF AMMONIUM ION BY DIBENZO- 18-CROWN-6 AND CALMAGITE

An extraction-spectrophotometric method for the determination of trace amounts of ammonium ion is described. Ammonium ion is effectively extracted as a neutral ternary complex NH . DB 18C6. calmagite at pH 3.0 into chloroform, followed by spectrophotometric determination at =48 5 nm. Molar absorptivity of the ternary complex at this wavelength is 1.08 10 mol cm . Beer's law is obeyed over...