Re-Based Rectangles as Potential Low-Temperature Nanoprobes: Synthesis, Structure, and Study of Permittivity

Molecular metallacycles capable of undergoing specific movements upon thermal stimulation hold significant potential in various nanotechnology applications. In this study, Re-based rectangles were self-assembled via a one-pot synthesis, exhibiting thermal chair‒boat transformations. These transformations were confirmed using single-crystal X-ray diffraction analysis and ¹H NMR spectroscopy. Additionally, dielectric spectroscopy provided further physical evidence of these conformational transformations, revealing a linear relationship between the dielectric constant and the thermal vibrations of the molecular rectangles at low temperatures. This chair‒boat transformation in Re-based molecular rectangles represents a significant and encouraging advancement, paving the way for novel applications of such molecules as low-temperature-dependent dielectrics. This work also adds a compelling dimension to the intriguing field of molecular metallacycles.