Solvent-Switched Schiff-Base Macrocycles: Self-Sorting and Self-Assembly-Dependent Unconventional Organic Particles

Organic
reaction is a powerful and versatile tool for the creation
of various new substrates and materials. However, there have been
few reports of the direct fabrication of organic particles by organic
reactions. Herein, we report that water as a co-solvent can efficiently
switch a [2 + 2] macrocycle (3) to a [1 + 1] macrocycle
(4) in a Schiff-base reaction from the same precursors
at room temperature. Unexpectedly, a series of tunable organic micro/nanoparticles,
including solid microspheres, core–shell spheres, and vesicles,
could be directly precipitated in one-step from the reaction medium
with high yield. X-ray structure analysis and other characterizations
indicated that social self-sorting and narcissistic
self-sorting of the macrocyclic frameworks of 3 and 4 through noncovalent interactions play crucial
roles in the formation of such organic particles. Most interestingly,
the facile and mild fabrication conditions of the particles allowed
us to accurately and in situ monitor their intermediate
formation by controlling the reaction time. This work thus provides
an advancement of the fabrication of tunable organic particles.