Syntheses, Structure, and Fluorescent Probes for Sensitive Detection for Nitrobenzene of Two Cd(II) Coordination Polymers

Two Cd(II)-based coordination polymers (Cd-CPs), named {[Cd(casb)(bbibpy)]·2H2O}n (Cd-CP-1) and [Cd(bpydb)(bbibpy)(H2O)]n (Cd-CP-2), were successfully constructed under the condition of solvothermal (H2casb is 4-((carboxylatoethyl)sulfanyl)benzoic acid, H2bpydb is 4,4'-(4,2'-bipyridine-2,6-diyl)dibenzoic acid, bbibpy is 5,5'-bis(benzimidazol-2-yl)-2,2′-bipyridine]. Cd-CP-1 and Cd-CP-2 were characterized by X-ray single-crystal diffraction, elemental analysis and thermogravimetric (TG) analysis. X‑ray single crystal diffraction analysis reveals that Cd-CP-1 has a one-dimensional (1D) ladder structure and crystallizes in the triclinic system, space group P-1, and Cd-CP-2 has a 1D chain structure and crystallizes in the monoclinic system, space group P21/c. Furthermore, the fluorescence quenching experimental results showed that Cd-CP-1 and Cd-CP-2 exhibit selective fluorescence sensing nitrobenzene. The concentration-fluorescence experimental results showed that the detection limits of two complexes for nitrobenzene are 6.54 × 10–6 M, 1.17 × 10–7 M based on 3σ/Ksv, respectively.