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Two novel lead(II) coordination polymers with the same mixed ligands, [Pb(AAP)(NIP)] ( I) and {[Pb(AAP)(NIP)] · 2HO} ( II) (AAP = 4-aminoantipyrine and NIP = 5-nitroisophthalate), were prepared by controlling the pH value of the reaction mixture. Complexes I and II were characterized by X-ray single-crystal diffraction analyses (CIF files CCDC nos. 936101 ( I) and 936102 ( II)). Complex I with terminal AAP molecule displays a linear chain with hemidirected Pb ions connected by bis-bidentate chelating-NIP anions. By contrast, complex II exhibits a dimeric {Pb(AAP)}-based coplanar layer extended by bidentate chelating-bidentate chelating and bridging-NIP anions. Obviously, the pH-directed structural difference is dominated by the competitive binding modes of the AAP and carboxylate groups of NIP ligands. Both complexes display different thermal stability due to structural difference and similar emissions originated from the intra- and/or inter-ligand electron transfer, suggesting their potential application as luminescent materials. [ABSTRACT FROM AUTHOR]

A novel layered MOF, {[Pb(HBic)(HBic)Cl] · 2HO} ( I), was hydrothermally obtained by the reaction of PbCl with 1- H-benzimidazole-5-carboxylic acid (HBic) and fully characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR, TG-DTA, and luminescent spectra. Structural analysis suggests that complex I is a 2D layer assembled from helical Pb(II)-HBicchains and bridging chloride linkers, which is H-bonded together into a 3D supramolecular network. Additionally, I in the solid-state exhibits a favorable fluorescent emission at room temperature due to the intraligand charge transfer, suggesting its potential application as fluorescence materials. [ABSTRACT FROM AUTHOR]