A Zn-based coordination polymer with good ability for selective detectionof mercury ions in solution

[Zn(NCS)Cl(L)]n (Zn-SCP) is a one-dimensional coordination polymer with a terminalthiocyanate group. The flexible sulfur donor ligand is bridged between metal centers by the antianti-anti conformation which forms an infinite ۱D zigzag chain and the third and fourthcoordination spheres are occupied by terminal Cl- and NCS- anions [۱]. Considering the HSABconcept (Hard-Soft Acid Base) [۲], N-coordinated thiocyanate as a Lewis base has a good potentialfor coordinating mercury from its free sulfur atom. In this work, we have used Zn-SCP for thedetection of Hg۲+ from water solution with different consecrations. Mercury has been coordinatedto the free sulfur of thiocyanate groups as it was excepted. The IR spectrum of Zn-SCP showed aremarkable shift for the NCS peak from ۲۰۷۰ cm-۱ to ۲۱۲۰ cm-۱ which clearly shows the changein the coordination sphere. The white color of Zn-SCP powder was changed to grey bycoordination with mercury [۳]. It is worth mentioning that Zn-SCP has selectivity in the detectionof mercury and there were no changes for other metals such as Pb۲+, Cd۲+, or copper. FT-IR, UVvisible,and ICP have confirmed the binding of mercury to thiocyanate. The Hg۲+ ions which arecoordinated to the Zn-SCP could be removed from the water solution by simple filtration.

Keywords:

Mercury detection , Sulfur coordination polymer , Zn complex , Methimazolebased ligands