A Bis-Crown Ether Derivative of Triaminotriazine: Synthesis and Behavior of the Ion-Selective and Hydrogen-Bonding Responsive Rotamers

Article abstract of DOI:10.1246/bcsj.70.671

A bis-crown ether derivative of triaminotriazine was synthesized via a phthalic acid derivative of a polyether macrocycle obtained from benzo-18-crown-6. It exists in different conformers distinguishable by ¹H NMR at room temperature, in which the macrocyclic side-arms take a closed, half-open, or fully open form, due to the rotational barrier of the C(triazine)-N bond. Large alkali metal ions, such as Rb⁺ and Cs⁺, the latter being particularly effective, promote the formation of the closed conformer. A barbiturate derivative also causes a similar equilibrium shift to the closed form by establishing complementary hydrogen bonds. The half-open and fully open conformers are induced by smaller alkali metal ions than Rb⁺, among which K⁺ is the most effective.