Two novel entangled metal–quinolone complexes with self-threading and polythreaded characters

Reactions of quinolones with metal salts in the presence of aromatic polycarboxylate ligands under hydrothermal conditions yield two novel entangled metal–quinolone complexes, namely [Cd2(saraH)2(bpdc)2]·4.5H2O (1) and [Mn(sara)2]·2.5H2O (2), (saraH = sarafloxacin, bpdc = 4,4′-biphenyldicarboxylate). Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, X-ray powder diffraction, and TG analyses. Compound 1 is an uncommon 2D self-threading network, which represents the first entangled network constructed from mixed sarafloxacin and dicarboxylate ligands. Compound 2 exhibits a novel (2D → 3D) polythreaded architecture that is constructed from 2D 44-sql nets with side arms, which represents the first example of polythreaded metal–sarafloxacin complex. A comparison of the structures of 1 and 2 shows that the pH plays a crucial role in tuning the structures of the metal–quinolone complexes. Furthermore, the luminescent properties of compound 1 are discussed.