Spontaneous resolution of novel Zn complexes in the formation of 3D metal–organic frameworks based on 2,2′-biimidazole ligand

The novel three-dimensional chiral framework of the four-coordinate zinc complexes, [Zn4(biim)3(ina)2] (1a and 1b) (H2biim = 2,2′-biimidazole, ina = isoniconate), has been prepared via hydrothermal reaction. X-ray single crystal diffraction analysis shows the biim2− in title complexes acts as a tetradentate ligand and links four different Zn2+ ions. Spontaneous chiral resolution occurs in solvo-thermal reaction, which was confirmed by solid-state circular dichroism spectra. Photoluminescent spectra of compound 1 exhibit an intense blue emission at 440 nm.