Integration of a semi-rigid proline ligand and 4,4′-bipyridine in the synthesis of homochiral metal-organic frameworks with helicesElectronic supplementary information (ESI) available: IR spectra, TGA, powder X-ray diffraction patterns and CIF files. CCDC 1050241 and 1050242. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt01151e

A pair of 3-D homochiral metal-organic frameworks (HMOFs) based on a mixed semi-rigid 5-(2-carboxypyrrolidine-1-carbonyl)isophthalate (PIA) ligand and rigid 4,4′-bipyridine (bipy), [Co 3 (( R )-PIA) 2 (bipy) 3 ]·6H 2 O ( 1-D ) and [Co 3 (( S )-PIA) 2 (bipy) 3 ]·6H 2 O ( 1-L ) are synthesized and structurally characterized. They are enantiomers and exhibit three-dimensional open frameworks. In each structure, the PIA ligands link the Co centers into homochiral frameworks with large open channels that are occupied by the bipy ligands. Interesting helical chains built from the connectivity between PIA ligands and Co centers are presented. Antiferromagnetic coupling is observed in 1-D . These results demonstrated that the mixed ligand approach is successful for the construction of HMOFs. A pair of 3D HMOFs have been synthesized, which contain helical chains and large open channels that are occupied by bipy.