Structural diversity and fluorescent properties of new metal–organic frameworks constructed from pamoic acid and different N-donor ligands

Abstract

Five new metal–organic frameworks, namely [Cd(PA)(H2O)(DMF)2]n (1), {[Co(PA)(4,4′-bipy)(H2O) (CH3OH)]·DMF}n (2), {[Cd2(PA)2(4,4′-bipy)1.5(H2O)3]·2DMF·2H2O}n (3), {[Ni(PA)(bpp)(H2O)2]·DMF}n (4) and {[Cd(PA)(bpp)(CH3OH)]·CH3OH}n (5), (H2PA=pamoic acid, 4,4′-bipy=4,4′-bipyridine, bpp=1,3-bi(4-pyridyl) propane), have been solvothermally synthesized and characterized by elemental analysis, IR and X-ray diffraction. Complex 1 displays a zigzag chain structure, while both 2 and 4 are 2D layered polymers. In complex 3, two crystallographically independent Cd2+ ions are bridged by PA2− anions alternately to form an infinite (Cd–PA2−)n chain, which extends into a 2D network through 4,4′-bipy linkers. Complex 5 possesses a 3D framework with the point symbol of (83·102·12). Various weak interactions may play a key role in stabilizing the observed structures. Their luminescent properties and thermal stabilities have also been investigated. Complex 5 displays strong green luminescence with an emission maximum at 548nm.