The efficiency of a series of amino-azacryptands for encapsulation and extraction of the oxoanions pertechnetate and perrhenate from aqueous solution is investigated and compared with that of their open-chain counterparts. The aqueous formation constants for oxoanion association with the cryptands were determined by pH potentiometry and/or NMR, and X-ray analysis of single crystals provides evidence for encapsulation. The extractabilities could not be explained solely on the basis of ligand lipophilicity; the level of protonation also plays an important role.
研究了一系列氨基偶氮隐含物从水溶液中封装和萃取过硫酸盐和过铼酸盐氧阴离子的效率,并将其与开链对应物的效率进行了比较。通过 pH 电位法和/或核磁共振法测定了氧阴离子与隐晶质结合的水形成常数,单晶体的 X 射线分析提供了封装的证据。萃取能力不能仅根据配体的亲油性来解释,质子化水平也起着重要作用。
N-methylation of macrobicycles reduces encapsulation ability
作者:Sofia Derossi、David T. Farrell、Charles J. Harding、Vickie McKee、Jane Nelson
DOI:10.1039/b617907j
日期:——
N-methylation alters the conformation of octa-azacryptands leaving them unable to use all potential N-donors to coordinate copper(II) and anionic guests. This restriction, in the presence of other donors, normally results in exogenous coordination, with the exception of carbonate complexes, where two O-donors from the bridging anion along with three N-donors from the cryptand serve, in this series uniquely, to retain a pair of copper(II) ions within the “basket-shaped” cavity.
N 甲基化改变了八氮杂隐色体的构象,使其无法利用所有潜在的 N 供体来配位铜(II)和阴离子客体。在有其他供体存在的情况下,这种限制通常会导致外源配位,但碳酸盐复合物除外,在该系列中,桥接阴离子的两个 O-供体和隐色体的三个 N-供体共同作用,将一对铜(II)离子保留在 "篮状 "空腔中。