Proton inclusion properties of a new azamacrocycle. Synthesis, characterization and crystal structure of [H3L][Cl]3·2H2O (L = 4,10-dimethyl-1,4,7,10-tetraazabicyclo [5.5.2] tetradecane)

Abstract

Macrocyclic compounds have been extensively investigated, the interest for this huge class of compounds spans from fundamental research to specific industrial applications. ^{1 – 8} We have recently published a few papers on small macrocycles having cage-like molecular topology.^{9 – 19} They present special proton-transfer properties and in few cases they are strong, selective lithium binders in aqueous solution.^14,15,17 The three-dimensional cavity present in these compounds is achieved by connecting two secondary nitrogen atoms of a tetraazamacrocycle with different bridging groups (see Fig 1). Molecular topology and nature of donor atoms are the most important elements influencing the chemical properties of this class of compounds. For these reasons we are continuing our investigations on these compounds by systematically changing the bridging unit; we report here the synthesis and chemical properties of the new cage 4,10-dimethyl-1,4,7,10-tetraazabicyclo[5.5.2]-tetradecane, abbreviated as L.