Synthesis and solid state structure of thermally stable linear bi–pyrazoles

The long and rigid bi-pyrazolyl-based ligands 2,6-bis[4-(1H-pyrazol-4-yl)phenyl]pyrrolo[3,4-f]isoindole-1,3,5,7(2H,6H)-tetrone, L1, and 2,5-bis[4-(1H-pyrazol-4-yl)phenyl]thiazolo[5,4-d]thiazole, L2, were isolated in pure form, with satisfying yields, as very insoluble polycrystalline materials. Their thermal behavior was investigated by coupling thermal analyses and variable-temperature X-ray powder diffraction measurements. Their crystal structures were unraveled from powder diffraction data by a rather unconventional structure determination approach, without the a priori knowledge of the unit cell parameters. Inline with shorter analogues, successfully employed in the formation of porous MOFs with intriguing functional properties, L1 and L2 are promising to construct higher-porosity materials, potentially capable of hosting nano-sized guests.