Isomer separation remains a significant challenge in the chemical industry due to their similar physiochemical properties, such as boiling points differing by as little as one degree. Conventional techniques such as fractional distillation and adsorption are resource-intensive, often yielding mixtures that require further purification. Host–guest chemistry, a branch of supramolecular chemistry, presents an innovative alternative, overcoming many of the limitations associated with conventional methodologies. This approach leverages the structural attributes of both host and guest, whereby the host participates in noncovalent interactions (such as hydrogen bonding, π⋯π stacking and C–H···π close contacts) with specific guest molecules to obtain stable inclusion complexes. This non-destructive and recyclable separation strategy not only enhances efficiency but also aligns with green chemistry principles by minimizing solvent waste and energy consumption.

 

In the current investigation, the potential of 9,9′-bifluorenyl-9,9′-diol (H) to behave as a selective host compound for the separation of pyridine (PYR) and its methylated derivatives, 2-, 3-, and 4-methylpyridine (2MP, 3MP, and 4MP) through supramolecular host-guest strategies was assessed. All of the inclusion complexes were examined using single crystal X-ray diffraction (SCXRD) experiments, while Hirshfeld surfaces and thermoanalytical analyses were also considered.