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 (P) in (IO)3 (from
2-aminopyridine) and (R) in (26IO)3 (from 2-aminopyrimidine). The tennimide crystal structure
(26IO)4 (from 2-aminopyrimidine)
exhibits three discrete conformational states, highlighting subtle
geometric changes with the tennimide channel (pore) open (o) and/or closed (c), as noted by three
macrocycle conformations with their channel pores observed as cc/oc/oo. Macrocycle formation
(though in competition with oligomer/polymer formation) relies on
the o-pyr­(im)­idine N functionality and preorganized imide hinge (the “CO···CO”
twist) together with the inherent flexibility of the isophthaloyl
groups.