Two reversible transformable mercury(ii) coordination polymers as efficient adsorbents for removal of dibenzothiophene

Abstract

Three new compounds of Hg(II) have been synthesized, [Hg(quinoxaline)₂(NO₂)₂] (1), [Hg₃(μ-quinoxaline)₂(μ-SCN)₆]_n (2) and [Hg(μ-quinoxaline)(μ-CN)₂]_n (3) through the reaction between a quinoxaline ligand and mercury(II) salts which have then been analyzed using IR spectroscopy and thermal gravimetric (TGA) analysis. Furthermore, these compounds have also been characterized using single-crystal X-ray crystallography. The single-crystal X-ray data of compound 1 shows the complex to be a monomer of mercury(II). The structural studies of compounds 2 and 3 show that these structures are two- and three-dimensional coordination polymers of mercury(II). Under mild reaction conditions, the mentioned compounds exhibited high efficiency and reusability in desulfurization removal of model oil which was prepared by dissolving dibenzothiophene in n-hexane. Furthermore, the DBT removal in the solution obeys first order reaction kinetics and the activation energy of the adsorption process was found to be 16.57 kJ mol⁻¹. Finally, solid state crystal to crystal transformation of these compounds was investigated.