Highly stable Ni(II)/Zn(II)-CPs as multiresponsive luminescent sensors for detection of IO₄⁻, 2,6-dichloro-4-nitrophenol and folic acid

Coordination polymer (CP) materials have an important application as sensors. In this work, two new Ni(II)/Zn(II)-CPs of sebacic acid (H₂seb) and 1,6-bis(benzimidazole)hexane (bbimh), {[Ni₃(seb)₃(bbimh)₄]·7H₂O}_n (1) and {[Zn(seb)(bbimh)]·H₂O}_n (2), were constructed as luminescent sensors. Ni(II)-CP 1 features a three-dimensional (3D) (4,5)-connected framework including 1D channels occupied by water molecules. Zn(II)-CP 2 shows a 3D supramolecular network with 6-connected pcu topology. Both CPs have good stability in aqueous solution as well as in EtOH. Luminescence sensing studies reveal that 1 and 2 display high luminescence quenching efficiency toward IO₄⁻, 2,6-dichloro-4-nitrophenol (2,6-DCNP) and folic acid (FA). Both CPs also display excellent sensitivity with limits of detection toward IO₄⁻, 2,6-DCNP and FA as low as 1.23 μM, 13.26 nM and 13.04 μM for 1 and 1.26 μM, 30.61 nM and 15.70 μM for 2, respectively. Additionally, the two CPs were also demonstrated to be ultrasensitive and selective sensors for the detection of IO₄⁻ in swimming pool water, 2,6-DCNP in farmland sewage and FA in human serum. The experimental results suggest that the synthesized Ni(II)/Zn(II)-CPs have potential application as luminescence sensing materials in environmental pollution and human health.