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

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 548 nm.

Graphical abstractFive new metal–organic frameworks exhibiting structural diversity, from infinite chain to 3D framework, have been synthesized from reactions with pamoic acid (H2PA) under solvothermal conditions. The compound {[Cd(PA)(bpp)(CH3OH)]·CH3OH}n displays strong green luminescence with an emission maximum at 548 nm.Figure optionsDownload full-size imageDownload as PowerPoint slide