Tunable Coordinative Assembly of a Disc-Like Molecule and Metal Ions: From Mirospheres to Microtubes and Microrods

This study reports a tunable metallo-supramolecular assembly strategy to construct microscaled objects with different morphologies. Three well-defined discrete microstructures—microspheres, microtubes, and microrods—have been fabricated through metal−organic coordination between the same organic unit and different transition metal ions or the same organic unit and metal ion processed in different solvents. The formations of microspheres, microtubes, and microrods have been readily evidenced by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Encapsulation experiments revealed that those microspheres could entrap rhodamine B and might be used as carrier materials. It was also found that the microrods and microtubes could be transformed into each other by adding or removing water to or from the solution. The formation mechanisms of these microstructures have also been discussed on the basis of spectroscopic and crystallographic studies.