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Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water†
Organic & Biomolecular Chemistry ( IF 3.2 ) Pub Date : 2017-12-13 00:00:00 , DOI: 10.1039/c7ob02955a
Nikola Cindro 1, 2, 3, 4 , Josip Požar 1, 2, 3, 4 , Dajana Barišić 1, 2, 3, 4 , Nikola Bregović 1, 2, 3, 4 , Katarina Pičuljan 1, 2, 3, 4 , Renato Tomaš 4, 5, 6, 7 , Leo Frkanec 3, 4, 8 , Vladislav Tomišić 1, 2, 3, 4
Affiliation  

Cation complexation in water presents a unique challenge in calixarene chemistry, mostly due to the fact that a vast majority of calixarene-based cation receptors is not soluble in water or their solubility has been achieved by introducing functionalities capable of (de)protonation. Such an approach inevitably involves the presence of counterions which compete with target cations for the calixarene binding site, and also rather often requires the use of ion-containing buffer solutions in order to control the pH. Herein we devised a new strategy towards the solution of this problem, based on introducing carbohydrate units at the lower or upper rim of calix[4]arenes which comprise efficient cation binding sites. In this context, we prepared neutral, water-soluble receptors with secondary or tertiary amide coordinating groups, and studied their complexation with alkali metal cations in aqueous and methanol (for the comparison purpose) solutions. Complexation thermodynamics was quantitatively characterized by UV spectrometry and isothermal titration calorimetry, revealing that one of the prepared tertiary amide derivatives is capable of remarkably efficient (log K ≈ 5) and selective binding of sodium cations among alkali metal cations in water. Given the ease of the synthetic procedure used, and thus the variety of accessible analogues, this study can serve as a platform for the development of reagents for diverse purposes in aqueous media.

中文翻译:

中性糖共轭酰胺基杯[4]芳烃:水中的碱金属阳离子络合

水中的阳离子络合在杯芳烃化学中提出了独特的挑战,这主要是由于以下事实:大部分杯芳烃基阳离子受体不溶于水,或者通过引入能够(去质子化)的官能团实现了它们的溶解性。这种方法不可避免地涉及与目标阳离子竞争杯芳烃结合位点的抗衡离子的存在,并且还常常需要使用含离子的缓冲溶液以控制pH。本文中,我们在杯状[4]芳烃的下边缘或上边缘引入碳水化合物单元的基础上,设计了一种解决该问题的新策略,该碳水化合物单元包含有效的阳离子结合位点。在这种情况下,我们制备了具有仲或叔酰胺配位基团的中性水溶性受体,并研究了它们与碱金属阳离子在水溶液和甲醇(用于比较目的)中的络合作用。通过紫外光谱法和等温滴定量热法对络合热力学进行了定量表征,结果表明,所制备的叔酰胺衍生物之一具有显着的高效性(对数 ķ ≈5)和选择性在水中的碱金属阳离子中钠阳离子的结合。考虑到所用合成方法的简便性,以及由此获得的各种类似物的简便性,本研究可以作为开发用于水性介质中多种用途的试剂的平台。
更新日期:2017-12-13
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