Two chemically robust Cd(ii)-frameworks for efficient sensing of levofloxacin, benzaldehyde, and Fe3+ ions

Abstract

Two luminescent Cd(II)–organic frameworks [Cd₂(L1)(tdc)₂(H₂O)]_n (1) and [Cd(L2)_0.5(tdc)]_n (2) (L1 = 1,5-bis(1-(pyridine-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)pentane, L2 = 1,6-bis(1-(pyridine-4-ylmethyl)-1H-benzo[d]imidazol-2-yl)hexane, and H₂tdc = 2,5-thiophenedicarboxylic acid) were hydrothermally synthesized and characterized. 1 displays a rare binodal (3,4)-connected 2D cem-d network, while 2 exhibits a 3D mog (moganite) framework. The two MOFs are highly thermally durable and water-stable in a wide pH range from 3 to 12. Interestingly, 1 and 2 represent the first reported examples of multi-responsive probes based on MOFs for selectively detecting levofloxacin, benzaldehyde, and Fe³⁺ ions with reusability. The luminescence sensing mechanisms of the two CPs were explored in detail.