Takashi Funaki

Synthesis and Complexing Ability of Azacrownophanes: The Cyclodextrin Catalysis of the Photochemical Cyclization Reaction

Azacrownophanes were efficiently prepared by the irradiation of precursor ammonium chlorides in the presence of γ-CD (γ-cyclodextrin) in aqueous solution, by repressing the amino group-quenching effect by inclusion of the styrene moieties in γ-CD. In liquid–liquid extraction, azacrownophanes (6 and 7) showed affinity toward both Ag+ and Pb2+ cations in a series of heavy metal nitrates. Both 6 and 7 formed 1:1 complexes with the above two cations, according to 13C NMR titration and ESI-MS analysis.

Synthesis and complexing properties of crownophanes possessing carboxyl group

A new series of crown compounds bearing two carboxyl groups (2a-c; crownophanedicarboxylic acids) were prepared via intramolecular [2 + 2] photocycloaddition of bis-styrene derivatives. In the liquid-liquid extraction, crownophanedicarboxylic acids (2a-c) showed a low affinity toward alkali metal cations, though both 2b and 2c showed an extraordinary high affinity toward zinc cation among heavy metal cations examined.

A Pseudo Thiacrown Compound Formed by Hydrophobic Interaction of its Lipophilic Parts in Water: Ag-Selective Fluorophore in Water

Amphiphilic podand (3) was prepared by conventional thioether synthesis in ethanol. It shows exclusive selectivity toward Ag + ion in a liquid-liquid extraction. It was also found to exhibit selective fluorescence decrease only in the presence of Ag + ion in water. From the fluorometric titration, the complexing stability constant toward Ag + in water estimated to be log Ka = 4.2, which value is comparable to cyclic dithia-18-crown-6. This extraordinarily high value was caused by a pseudo cyclic structure formed in water, which was supported by 1 H NMR spectral analysis.