Rationally Designed, Polymeric, Extended Metal–Ciprofloxacin Complexes

Reactions of the antimicrobial fluoroquinolone ciprofloxacin (cfH) with metal salts in the presence of aromatic polycarboxylate ligands or under basic conditions produce fourteen new metal–cfH complexes, namely, [Ba 2 (cf) 2 (1,4‐bdc)(H 2 O) 2 ]⋅H 2 O ( 1 ), [Sr 6 (cf) 6 (1,4‐bdc) 3 (H 2 O) 6 ]⋅2 H 2 O ( 2 ), [M 2 (cfH) 2 (bptc)(H 2 O) 2 ]⋅8 H 2 O (M = Mn( 3) and Cd( 4 )), [M(cfH)(1,3‐bdc)] (M = Mn( 5 ), Co( 6 ), and Zn( 7 )), [Zn 2 (cfH) 4 (1,4‐bdc)](1,4‐bdc)⋅13 H 2 O ( 8 ), [Ca(cfH) 2 (1,2‐Hbdc) 2 ]⋅2 H 2 O ( 9 ) and [M(cf) 2 ]⋅2.5 H 2 O (M = Mn( 10 ), Co( 11 ), Zn( 12 ), Cd( 13 ), and Mg( 14 )) (1,4‐bdc = 1,4‐benzenedicarboxylate, bptc = 3,3′,4,4′‐benzophenonetetracarboxylate, 1,3‐bdc = 1,3‐benzenedicarboxylate, 1,2‐bdc = 1,2‐benzenedicarboxylate). Their structures were determined by single‐crystal X‐ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric analyses. The structures of 1 and 2 consist of unique two‐dimensional arm‐shaped layers. Compounds 3 and 4 are isostructural and feature one‐dimensional structures formed from the interconnection of [M 2 (cfH) 2 (H 2 O) 2 ] dimers with bptc ligands. Compounds 5 – 7 are isostructural and contain double‐chain‐like ribbons constructed from [M 2 (cfH) 2 (CO 2 ) 2 ] dimers and 1,3‐bdc. Compound 8 consists of a pair of [Zn(cfH) 2 ] 2+ fragments bridged by a 1,4‐bdc into a dinuclear dumbbell structure. Compound 9 is a neutral monomeric complex. To the best of our knowledge, compounds 1 – 9 are the first examples of metal‐quinolone complexes that contain aromatic polycarboxylate ligands. Compounds 10 – 14 are isostructural and exhibit interesting two‐dimensional rhombic grids featuring large cavities with dimensions of 13.6×13.6 Å. Up to now, polymeric extended metal–cfH complexes have never been reported.