Step-By-Step Tips to Grow X-Ray Quality Single Crystals of Metal Macrocyclic Complexes

Metal macrocyclic complexes, which are formed through a self-assembly process due to the presence of several coordinating sites in the metal and ligand source, represent an interesting class of complexes due to their intriguing structures and functionalities. Although spectral characterization of metal macrocyclic complexes is reported, elucidation of their exact structure at the molecular level remains challenging. Single-crystal X-ray diffraction (SCXRD) is a non-destructive analytical technique that can provide detailed information about the internal lattice of crystalline structure. However, it requires the growth of single crystals of suitable sizes and quality. This study provides an overview of methods that are most useful for developing single crystals of metal macrocyclic complexes, particularly when the macrocycle of interest is present in extremely low quantities (a few milligrams). The reproducibility of previous methods reporting the crystal growth of different metal macrocycles is also investigated. A review highlighting and summarizing the most common tips to grow single crystals for metal macrocyclic complexes can help in understanding and optimizing the growth of crystals suitable for SCXRD.

Automated summary

Metal macrocyclic complexes formed through self-assembly show interesting structures and functionalities, but their exact molecular structures remain challenging to determine. Single-crystal X-ray diffraction provides detailed information about crystalline structures, but requires suitable single crystals. This study provides an overview of methods for developing single crystals of metal macrocyclic complexes, especially in low quantities, and investigates the reproducibility of previous methods.