A series of new calixarene-based fluoroionophores were synthesized. With our new calixarene derivative bearing a crown ether and an azacrown ether as two binding sites, the metal ion was found to selectively choose its better binding pocket between these two ligands. Interesting "molecular taekowndo" processes between Ag(+)-K(+), Cu(2+)-K(+), and Ag(+)-Cs(+) pairs were easily monitored via fluorescence change.

A series of novel N-chromogenic calix[4]arene azacrown ethers were synthesized as selective extractants of potassium ion. 1,3-Alternate calix[4]arene azacrown ethers were prepared by reacting 25,27-dipropyloxy-26,28-bis(5-chloro-3-oxapentyloxy) calix[4]arenes with p-toluenesulfonamide in the presence of potassium carbonate. The coupling reaction of calix[4]arene azacrown ether with 2-hydroxy-5-nitrobenzyl bromide in the presence of triethylamine in THF gave the chromogenic calix[4]arene azacrown ether in moderate yield. These compounds show high potassium selectivity over other metal ions as shown by two-phase extraction, bulk liquid membrane, and 1H NMR studies on a ligand-metal complex. It is assumed that the OH of the chromogenic group attached on nitrogen can assist the complexation by encapsulation of the metal.

Novel 1,3-alternate calix[4]azacrowns having an azo chromophoric pendent group were synthesized, and their 1,3-alternate conformations were confirmed by X-ray crystal structure. In view of the hypsochromical UV band shifting upon cation complexation, azo-coupled calix[4]azacrown-5 (3) showed the most selective shifting with alkali and alkaline metal ions. In addition, 3 revealed K+ ion selectivity not only due to the size comparability between the K+ ion and the azacrown-5 loop but also due to a significant K+-pi interaction between the two aromatic rings and the K+ ion. The UV band shifting is also dependent on the lipophilicity of the species of counteranion used.

Two novel chromogenic 1,3-alternate calix[4]azacrown (1) and calix[4]-bis-azacrown (2) in which an indoaniline chromophore was attached on the nitrogen atom of the azacrown unit with one methylene spacer were synthesized. The 1H NMR spectrum of the ligand 1 and Ca2+ proved that the metal ion is entrapped by the calix[4]azacrown unit and by the conjugated indoaniline system. From the UV/vis band shifts upon metal ion complexation, Zn2+ ion was found to give the largest band shifts compared to other metal cations, indicating that Zn2+ ion (K(a) = 18 760 M(-)(1) for 1 and K(a) = 19 930 M(-1) for 2) was selectively encapsulated by the calix[4]azacrown cavity with assistance of the pendent indoaniline sidearm.

The 1,4-alternate tetrahomodioxacalix[4]arene tetraamide 4 with four p-phenyl groups on its upper rim was synthesized. In two-phase metal picrate extraction, 4 exhibited Pb2+ selectivity with formation of a 1:1 complex in chloroform. In the solid-state structure of the 4*Pb(Pic)2 complex, Pb2+ is bound by the carbonyl oxygens of two adjacent amide groups and an aryl-alkyl ether oxygen atom of one of these amide-containing substituents. The crystal structure and 1H NMR spectrum of the 4*Pb2+ complex reveals pi-metal ion complexation of one aromatic ring in the ligand with Pb2+.

The preparation of an 1,3-alternate calix[4]arene phosphorus ligand, 25,27-bis(2-(diphenylphosphino)ethoxy)-26,28-bis(1-propyloxy)calix[4]arene (3), is presented. Ligand 3 is obtained in three steps in 64% overall yield. Reaction of 3 with [Rh(cot)2]BF4 produced the encapsulated rhodium complex [Rh[(P,P)-diphen-calix[4]arene]]BF4 (4). As revealed by a single-crystal X-ray diffraction study, the rhodium center has a bent coordination environment with a P-Rh-P angle of 135.66(3) degrees. Palladation of 3 employing [Pd(MeCN)4](BF4)2 yielded the chelate palladium complex 7 in which the palladium center has a slightly bent configuration. Treatment of the ligand with Pd(cod)Cl2 and [Pd(eta3-C4H7)(THF)2]BF4 leads to the isolation of the monometallic complex. Full characterization includes X-ray structural studies of compounds 3, 4, and 6.

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