Kwanghyun No

Two novel 1,3-calix[4]azacrowns

Abstract Two 1,3-calix[4]azacrowns-5 in the 1,3-alternate conformation have been constructed from calix[4]arene. They formed 1:1 endo and 1:2 endo–endo complexes with NH 4 + in CDCl 3 . Comparison with 1,3-calix[4]-bis-crown-5 lead us to conclude a better binding by replacement of the central O atom by NH group in the crown.

Ferrocene-based anion receptor bearing amide and triazolium donor groups

A novel ferrocene-based anion receptor bearing amide and triazolium donor groups and its anion complexation have been reported. We found that it shows marked electrochemical selectivity to F(-), followed by AcO(-) > Cl(-) > Br(-) > I(-), which is in accordance with (1)H NMR titration results.

Intramolecular hydrogen bonding effect on metal ion complexation of homooxacalix[4]arene bearing tetraamides

Abstract N,N-Dipentylamido homooxacalix[4]arene ( 3 ) in the C-1,2-alternate conformation provided Pb2+ ion selectivity over other metal cations. N-Monopentylamido homooxacalix[4]arene in C-1,2-alternate conformation has an intramolecular hydrogen bonding, causing decrease of the metal ion complex ability.

Fluorescent Change Of Pyreneamide Bearing Calix[4]crown-5: Inhibit Logic Gate In K+-induced Complexation

The fluorescence excimer emission of 1 is found to be enhanced upon the addition of K+ ion which is due to a conformational change of the ligand to have a more efficient π–π* interaction of two pyrenes. By contrast, no fluorescence change of 1 was observed in the anion binding test with F− , Cl− , Br− , I− , , , and as their tetrabutylammonium salts in MeCN. Interestingly, it was observed that the excimer emission of the two pyrenes decreases upon the addition of or in the 1√K+ complex solution. This is presumably due to a conformational change of the ligand by K+ ion binding, which induces the better conformation of two facing pyrene amides to selectively adopt or ion. This allosterical anion complexation could be applicable for NOR and INHIBIT (INH) logic gates.

1,3-Alternate and C-1,2-Alternate Tetrahomodioxacalix[4]crowns. Crystal Structures and Metal Ion Complexation

Two novel tetrahomodioxacalix[4]crowns with crown-5 and crown-6 rings weresynthesized. From X-ray crystal structures, homooxacalix[4]crown-5 (3) andhomooxacalix[4]crown-6 (2) were found to be in the 1,3-alternate and theC-1,2-alternate conformations, respectively. Homooxacalix[4]crown-5 (1)shows a marked selectivity for cesium ion over other metal ions tested.