Anion Dependent Water Clusters Encapsulated Inside a Cryptand Cavity

A series of water clusters encapsulated inside a cryptand cavity were obtained in the cryptand-acid supramolecular adducts of [(H2O)2⊂(H6L)][H2PO4]6(H2O)3 (1·3H2O), [(H2O)3⊂(H6L)][H2PO4]6(H2O)11 (2·11H2O), [(H2O)3⊂(H6L)][CH3(C6H4-p)SO3]6(H2O)4 (3·4H2O), and [(H2O)6⊂(H6L)][SO4]3(H2O)13 (4·13H2O) (L = N[(CH2)2NHCH2(C6H4-p)CH2NH(CH2)2]3N). In 1 and 2, H6L6+ is hydrogen bonded to six H2PO4− through its protonated nitrogen atoms to form two (O···H−N−H···)3 rings at two poles of H6L6+. A well encapsulated water dimer, and a circle- and cage-shaped trimer of [H2PO4]3 are formed in 1. A well encapsulated circular water trimer and a bowl-shaped trimer of [H2PO4]3 are formed in 2. In 3, the steric effect of the tolyl group of [CH3(C6H4-p)SO3]− causes a change in the conformation of H6L6+ to generate a favorable environment for a linear water trimer inside the crystand cavity. In 4, H6L6+ bonds three SO42− anions through the protonated nitrogen atoms at the one pole, and a quasi-prismatic hexamer water cluster is formed inside the cryptand cavity.

一系列封装于穴状配体（cryptand）空腔内的水团簇，可从以下四类穴状配体-酸类超分子加合物中获得：[(H₂O)₂⊂(H₆L)][H₂PO₄]₆(H₂O)₃ (1·3H₂O)、[(H₂O)₃⊂(H₆L)][H₂PO₄]₆(H₂O)₁₁ (2·11H₂O)、[(H₂O)₃⊂(H₆L)][CH₃(C₆H₄-p)SO₃]₆(H₂O)₄ (3·4H₂O) 以及 [(H₂O)₆⊂(H₆L)][SO₄]₃(H₂O)₁₃ (4·13H₂O)（其中配体L = N[(CH₂)₂NHCH₂(C₆H₄-p)CH₂NH(CH₂)₂]₃N）。在化合物1与2中，H₆L⁶+通过其质子化氮原子与六个H₂PO₄⁻形成氢键，在H₆L⁶+的两个极区构建出两个(O···H−N−H···)₃环状结构。在1的空腔内，形成了封装完好的水二聚体，以及由[H₂PO₄]₃构成的环状笼状三聚体；在2的空腔内，则形成了封装完好的环状水三聚体，以及由[H₂PO₄]₃构成的碗状三聚体。在化合物3中，[CH₃(C₆H₄-p)SO₃]⁻的甲苯基空间位阻效应会改变H₆L⁶+的构象，进而在穴状配体空腔内为线性水三聚体创造出有利的组装环境。在化合物4中，H₆L⁶+通过其单极的质子化氮原子与三个SO₄²⁻阴离子成键，穴状配体空腔内形成了准棱柱形的水六聚体团簇。