For functional nitrogen-bridged calix(hetero)aromatic platforms to be further used in the design of more sophisticated receptors, the azacalix[2]arene[2]triazine nitrogen bridges were functionalised with methyl bromoacetate. Three new macrocycles with four N-methyl ester pendant arms were straightforwardly prepared in good yields from the undecorated azacalix[2]arene[2]triazine precursors with chlorine, dimethylamine or dihexylamine substituted triazines. These intermediate macrocycles exhibited different reactivity towards the nucleophilic replacement, which was rationalized from the computed electrostatic potential for these molecules. Subsequently, the N-methyl ester appendages were hydrolyzed with each dialkylamine derivative providing a single macrocycle with four carboxylic groups. In contrast, the hydrolysis of the dichlorinated azacalix[2]arene[2]triazine analogue yielded a mixture of three isomeric macrocycles having two N-methyl esters and two carboxylmethyl pendant arms and the triazine chlorine atoms replaced by hydroxyl groups. The coordination ability of two macrocycles with four carboxylic groups for transition metals was evaluated with copper(II) by UV-vis titrations.
                                    为了将功能性氮桥
钙(杂)芳香族平台进一步用于设计更复杂的受体,我们用
溴乙酸甲酯对氮杂[2]炔[2]三嗪氮桥进行了功能化处理。用
氯、
二甲胺或
二己胺取代三嗪,从未经装饰的氮杂
吖丙啶并[2]炔并[2]三嗪前体中直接制备出了三种具有四个 N-甲基酯悬臂的新大环,产量很高。这些中间大环对亲核置换表现出不同的反应活性,这可以从计算出的这些分子的静电势中得到合理解释。随后,N-甲基酯附属物与每种二烷基胺衍
生物发生
水解,产生了具有四个羧基的单个大环。相反,二
氯化氮杂[2]炔[2]三嗪类似物的
水解则产生了三种异构大环的混合物,其中有两个 N-甲基酯和两个羧甲基垂臂,三嗪的
氯原子被羟基取代。通过紫外-可见滴定法,评估了带有四个羧基的两个大环与过渡
金属
铜(II)的配位能力。