Self-Assembly of Metal–Organic Cages in Microdroplets: An Interdisciplinary Teaching Module

Abstract

This teaching experiment presents an interdisciplinary platform that offers integrated training in organic synthesis, supramolecular assembly, microfluidics, and spectroscopic characterization by combining subcomponent self-assembly of metal–organic cages with droplet-based microfluidic technology. A microdroplet generation system is constructed to systematically investigate droplet formation at immiscible liquid interfaces, where controlled flow rates enable the reproducible production of size-tunable, monodisperse oil-in-solvent droplets. The influence of spatial confinement on supramolecular self-assembly is then examined by comparing the formation efficiency of cage C1, assembled from L1, 2-formylpyridine (L2), and Zn(NTf2)2 (L3), in conventional bulk vials and microdroplet environments. 1H NMR analysis demonstrates that complete assembly of C1 is achieved within 60 min under microdroplet confinement, whereas the corresponding bulk reaction remains incomplete even after 720 min. In addition, the aggregation-induced emission (AIE) behavior of cage C1 and its ligand component L1 is systematically explored using UV–vis absorption and fluorescence spectroscopy, elucidating the dependence of their photophysical properties on solvent composition. Overall, this experiment highlights the pedagogical value of integrating micro/nanoscale confinement with molecular self-assembly and provides an effective framework for cultivating students’ experimental skills in advanced synthesis, microfluidic manipulation, and spectral analysis.