Trezimides and Tennimides: New Imide-Based Macrocycles

The reaction of isophthaloyl dichloride with 2-aminopyridine or 2-aminopyrimidine provides a facile entry into a new class of imide-based “3 + 3” macrocyclic trimer (trezimide), together with the known tetramer scaffold (tennimide). The trezimides can adopt two distinct asymmetric conformations in the solid state, isolated as (<b>P</b>) in (<b>IO</b>)_<b>3</b> (from 2-aminopyridine) and (<b>R</b>) in (<b>26IO</b>)_<b>3</b> (from 2-aminopyrimidine). The tennimide crystal structure (<b>26IO</b>)_<b>4</b> (from 2-aminopyrimidine) exhibits three discrete conformational states, highlighting subtle geometric changes with the tennimide channel (pore) open (<i>o</i>) and/or closed (<i>c</i>), as noted by three macrocycle conformations with their channel pores observed as <i>cc</i>/<i>oc</i>/<i>oo</i>. Macrocycle formation (though in competition with oligomer/polymer formation) relies on the <i>o</i>-pyr­(im)­idine N functionality and <i>preorganized</i> imide <i>hinge</i> (the “CO···CO” twist) together with the inherent flexibility of the isophthaloyl groups