Two new Zn(II) and Cd(II) coordination polymers derived from 1,3,5-tris (3-carbonylphenyloxy)benzene and 4,4′-bis(imidazolyl)biphenyl ligands: Syntheses, structure and luminescent sensing of antibiotics

Two new coordination polymers with formulae [Zn(HL)(bb)]n (1) and [Cd(HL)(bb)]n (2) (H3L = 1,3,5-tris(3-carbonylphenyloxy)benzene and bb = 4,4 '-bis(imidazolyl)biphenyl) have been synthesized solvothermally and structurally characterized by elemental analysis, IR, single crystal X-ray diffraction and thermal analyses. Single crystal X-ray diffraction studies reveal that compounds 1 and 2 show similar three-fold interpenetrating 4-con-nected 2D framework structure with the sql topological net and the Schla center dot fli symbol of {44 & sdot;62} and are further extended into 3D supramolecular network by inter-molecular hydrogen bonding. Compound 1 have been used as turn-off luminescent sensor and displayed sensitive and selective luminescence sensing for nitrofurazone anti-biotic (NFZ) with Ksv of 0.87 x 103 M-1 and 1.98 ppm limit of detection (LOD). The plausible mechanistic pathway for the detrioration in the luminescent intensity of 1 in presence of antibiotics have been explained with the help of theoretical calculations. The calculations indicated that the decline in fluorescence intensity of 1 was accredited to the electron/energy transfer as well as weak interactions operating between 1 and antibiotic.