Super Uranophile, Water-Soluble Calixarenes: Their Metal Complexes, Stability Constants and Selective Reactivity to Uranyl Ion
Super Uranophile, Water-Soluble Calixarenes: Their Metal Complexes, Stability Constants and Selective Reactivity to Uranyl Ion
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超级亲铀剂、水溶性杯芳烃：其金属配合物、稳定性常数和对铀酰离子的选择性反应性
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发表时间：
1999
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通讯作者：
I. Yoshida
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作者：
M. Sonoda;M. Nishida;D. Ishii;I. Yoshida
以铀酰离子UO_2^2+为研究对象，在25℃、m =0.1的ph滴定条件下，研究了羟基杯[n]芳烃-对磺酸盐h_j_1 _n^n - (n =4,8; j = n /2, n =6; j =2)与不同金属离子的络合生成反应。根据h_1_n ^n -的ph滴定数据，确定了酸解常数：h_1_4 ^4 -的pk_a1 =3.25, pk_a2 =12.8， h_1_6 ^6 -的pk_a1 =3.28, pk_a2 =4.86， h_1_8 ^8 -的pk_a1 =3.73, pk_a2 =4.39, pk_a3 =8.07, pk_a4 =10.1。结果表明，所制备的配体是较强的多质子酸，在弱酸转碱性的水溶液中，每mol配体h_j1_ n n -，具有n mol羟基，可释放出j mol质子。四聚物配体,H_2 1 _4 ^ 4 -形成两个不稳定1:2 (UO_2 ^ 2 +:配体)复合物,[(UO_2 ^ 2 +) (1 _4 ^ 6 -) _2 (H ^ +)) ^ 9 - [(UO_2 ^ 2 +)(1 _4 ^ 6 -) _2) ^ 10 -,和六聚物配体,H_2 1 _6 ^ 6 -四个1:1形成复杂的物种,如[(UO_2 ^ 2 +) (1 _6 ^ 8 -)) ^ 6 - [(UO_2 ^ 2 +) (1 _6 ^ 8 -) (H ^ +) _-1] ^ 7 - [(UO_2 ^ 2 +) (1 _6 ^ 8 -) (H ^ +) _-2] ^ 8 -,和[(UO_2 ^ 2 +) (1 _6 ^ 8 -) (H ^ +) _-3] ^ 9——UO_2 ^ 2 +。根据它们的pk_a值、稳定性常数和配合物的组成（包括八聚体配体H_4 1 _8^8 -）评价了它们对UO_2^2+的选择性反应，并对其与各种金属离子的配合物形成反应进行了研究，发现形成了非常稳定的2:1配合物[(UO_2^2+)_2(1 _8^12 -)(H^+) _3]^11 -]。
The complex-formation reaction of hydroxycalix[ n ]arene- p -sulfonates, H_j 1 _n^n–( n =4,8; j = n /2, n =6; j =2), with various metal ions were studied while focusing on the uranyl ion, UO_2^2+, by the pH-titration method at 25ʰC and m =0.1. From the pH-titration data for H_j 1 _n^n–, the acid-dissociation constants were determined to be as follows: p K _a1=3.25, p K _a2=12.8 for H_2 1 _4^4–, p K _a1=3.28, p K _a2=4.86 for H_2 1 _6^6–, and p K _a1=3.73, p K _a2=4.39, p K _a3=8.07, p K _a4=10.1 for H_4 1 _8^8–. These results indicate that the present ligands are relatively strong multi-protonic acids which release j mol of proton from one mol of ligand, H_j 1 _ n n–, having n mol of hydroxyl group in a weakly acidic-to-alkaline aqueous solution. The tetramer ligand, H_2 1 _4^4– formed two unstable 1:2 (UO_2^2+:ligand) complexes, [(UO_2^2+)( 1 _4^6–)_2(H^+)]^9– and [(UO_2^2+)( 1 _4^6–)_2]^10–, and a hexamer ligand, H_2 1 _6^6– formed four 1:1 complex species, such as [(UO_2^2+)( 1 _6^8–)]^6–, [(UO_2^2+)( 1 _6^8–)(H^+)_–1]^7–, [(UO_2^2+)( 1 _6^8–)(H^+)_–2]^8–, and [(UO_2^2+)( 1 _6^8–)(H^+)_–3]^9– with UO_2^2+. Their selective reactivity to UO_2^2+ over other various metal ions was evaluated based on their p K _a values, stability constants and the compositions of the complexes including that for the octamer ligand, H_4 1 _8^8–, for which the complex-formation reactions with various metal ions were already studied and found to form an extremely stable 2:1 complex, [(UO_2^2+)_2( 1 _8^12–)(H^+)_–3]^11–.