Design and synthesis of hydrogen-bonded organic frameworks based on Ni4L4 cubane units

The construction of hydrogen-bonded organic frameworks (HOFs) by strong intermolecular hydrogen bonding interactions has received much attention in recent years. Different from common reported organic molecules based HOFs, we demonstrate here the Ni4L4 cubane (L ​= ​S-1,2-bis(benzimidazole-2-yl)) containing carboxylate ligands is a powerful subunit for the construction of HOFs. In this subunit, four Ni2+ ions are coordinated by four LH ligands to form typical cubane structure, two carboxylic ligands occupy the remaining four coordination sites in bridging mode. Based on this structure, a series of carboxylic ligands containing potential H-bond sites are employed to control the self-assembly of Ni4L4 cubane to generate different HOFs with improved stability and tunable magnetic properties.