Synthesis, Crystal Structures, H2S, and Iodine Uptake Properties of Four New Coordination Polymers Constructed from Group 12 Transition Metal Ions and a Bidentate Sulfur Donor Ligand

In the current work, we have managed to design and synthesize a set of four new sulfur coordination polymers, namely, [ZnCl2(Ls)2]n (1), [CdCl2(Ls)2]n(2), [Cd(NCS)(μ2-SCN)2(Ls)2]n(3), and {[Hg(μ2-Cl)(Ls)2]-[ClO4]}n(4) using a branch tube method. They have been fully characterized using several techniques including elemental analysis, Fourier transform infrared spectroscopy, powder X-ray diffraction, photoluminescence spectroscopy, UV−vis, and single-crystal X-ray diffraction. Polymer 1 was synthesized directly by the reaction of zinc ions with the L s ligand, while polymer 2, which is isostructural with 1, was synthesized by a single-crystal-to-single-crystal postsynthetic modification of polymer 1 where Zn(II) ions were substituted by Cd(II) ions. The effect of the anion on changing the topology has been carried out in polymer 3 using a thiocyanate anion in which SCN− groups were bonded to the metal centers in both terminal and bridging coordination fashions to form a two-dimensional network structure. The competition between halogen and uncoordinated perchlorate anions along with the Ls ligand constructed a cationic one-dimensional network structure in {[Hg(μ2-Cl)(Ls)2][ClO4]}n in which halogen atoms bridged between the metal centers and perchlorates counterbalanced the charge. The title polymers were considered as iodine and H2S adsorbents, and their kinetics were studied in detail. All polymers showed extreme stability toward both pollutants, and polymer 4 removed more than 99% of I2 from the solution. The presence of halogen and ClO4− anions in polymer 4 was the key factor for its best removal efficiency in this group