Hydrothermal syntheses and crystal structures of PbII coordination polymers based on a N,O-donor ligand

In this article, four new lead(II) coordination polymers based on a N,O-donor ligand 2′-(1 H-1,3,7,8-tetraaza-cyclopenta[l]phenanthren-2-yl)biphenyl-2-carboxylic acid (HL) have been hydrothermally synthesized, namely, [PbL2]·2H2O (1), [PbL2]·2H2O·CH3CH2OH (2), [Pb5L2(m-BDC)4]·3H2O (3) and [Pb2L2(p-BDC)] (4), where m-BDC = 1,3-benzenedicarboxylate and p-BDC = 1,4-benzenedicarboxylate. Compound 1 shows a 2D bilayer structure, which is further extended into a 3D supramolecular structure through π–π stacking interactions. Compound 2 shows a 3D supramolecular structure based on a zero-dimensional molecule by π–π stacking interactions of neighboring molecules. Compound 3 shows a 2D layer structure. Compound 4 displays a 1D chain-like structure, which is then stacked by π–π interactions to result in a 2D supramolecular structure. Solid-state luminescent spectra of four lead(II) complexes indicate intense fluorescent emissions.

Graphical abstractFour PbII metal-organic frameworks with distinct structures based on a N,O-donor ligand have been successfully synthesized by varying the solvents and organic aromatic acids, where photoluminescent properties were also investigated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Four lead(II) complexes have been hydrothermally synthesized. ► Phenanthroline derivative and two aromatic acids were used as the ligands. ► PL spectra of four complexes indicate intense fluorescent emissions.