Tribracchial lariat ethers, ‘TriBLEs,’ based on 4,10,16-triaza-18-crown-6: an apparent limit to sidearm contributions in lariat ether molecules

The development of an improved synthesis of 4,10,16-triaza-18-crown-6 (crystal structure shown) has permitted the synthesis of several novel derivatives of this well-known but little-studied compound and the finding that two-armed and three-armed derivatives exhibit comparable rather than markedly different cation binding strengths and selectivities.