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用光谱法研究了酮型,烃型和醇型三个系列双(4′—苯并—15—冠—5)与碱金属苦味酸盐在四氢呋喃溶液中的格络作用.△λ_(max)数据表明,这些双(4′—苯并—15—冠—5)与Na~+的络合作用很弱,与相应的单苯并—15—冠—5类似,但对K~+、Rb~+则有较大的络合能力。三个系列双(4′—苯并—15—冠—s)与离子半径较大的碱金属离子络合时,倾向于生成冠醚环与离子化学计量为2:1 的夹心络合物。生成这种2:l络合物的络合能力大小的顺序分别是3>2>1和K~+>Rb~+>CS~+.络合能力小的酮型双(4′—苯并—15—冠—5)(1)与离子半径大大的CS~+并不生成2:1络合物;相反,醇型双(4′—苯并—15—冠—5)(3)则不但容易与K~+、Rb~+,而且还可以与Cs~+生成2:1络合物。在所有考查过的双冠醚中,以3a对KPi的络合能力最大,它在Cr/K~+摩尔比为2:1时就已生成2:1夹心络合物。这可能是由于3a在浓度很小的条件下,分子内的二个羟基之间形成了氢键之故。有多数体况下当双冠醚与较大的碱金属离子相作用时,在较大的Cr/M~+比的范围内,1:1 和2:1两种组成的络合物同时存在于同一体系中.在高Cr/M~+比时,除了生成分子内2:1夹心络合物外,分子间2:1夹心络合物的生成也是可能的。
The lattice function of three series of bis (4’-benzo-15-crown-5) and alkali metal picrates in tetrahydrofuran solution was studied by spectroscopy. △ λ max The data show that the complexation of these bis (4’-benzo-15-crown-5) with Na ~ + is weak, similar to the corresponding monobenzo-15-crown- ~ + There is a greater ability to complex. Three series of bis (4’-benzo-15-crown-s) complexed with alkali ions with larger ionic radius tended to produce a sandwich complex with a crown ether ring and ion stoichiometry of 2: 1. The order of complexing ability of this 2: 1 complex was 3> 2> 1 and K +> Rb + CS + -15-crown-5) (1) The 2: 1 complex was not formed with CS ~ + with large ionic radius. On the other hand, the alcoholic bis (4’-benzo-15-crown- 5) Not only with K ~ +, Rb ~ +, but also with Cs ~ + 2: 1 complex formation. The highest complexation ability of 3a to KPi was observed among all the tested crown ethers, which generated a 2: 1 sandwich complex at a Cr / K ~ + molar ratio of 2: 1. This is probably due to the fact that 3a forms hydrogen bonds between the two hydroxyl groups in the molecule at very low concentrations. In most cases, when double-crown ether interacted with larger alkali metal ions, the complexes of 1: 1 and 2: 1 coexisted in the larger range of Cr / M ~ + ratio In the same system, at high Cr / M ~ + ratios, in addition to the intramolecular 2: 1 sandwich complexes, the formation of an intermolecular 2: 1 sandwich complex is also possible.