A BIS-CROWN ETHER DERIVATIVE OF TRIAMINOTRIAZINE - SYNTHESIS AND BEHAVIOR OF THE ION-SELECTIVE AND HYDROGEN-BONDING RESPONSIVE ROTAMERS

A bis-crown ether derivative of triaminotriazine was synthesized via a phthalic acid derivative of a polyether macrocycle obtained from benz o-18-crown-6. It exists in different conformers distinguishable by H-1 NMR at room temperature, in which the macrocyclic side-arms take a cl osed, 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 equil ibrium 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.