Synthesis, Structure, and Characterization of Two Zn/Cd Coordination Polymers with Flexible Disulfide Carboxylate Derivatives

Abstract

Two novel d10 metal coordination polymers [Cd2(Hmna)4]n (1), [Zn2(ddca)2 (dpe)]n·nH2O (2) (H2mna = 6‐mercaptonicotinic acid, H2ddca = 6, 6'‐dithiodinicotinic acid, dpe = 1, 2‐bis(4‐pyridyl)ethylene), were hydrothermally synthesized and characterized by single‐crystal X‐ray diffraction. Compound 1 is a cyclic double chain structure containing 16‐number and 32‐number circles with (Hmna)– ligands as bridges, in which the starting H2ddca reagent was unprecedentedly converted into H2mna ligands via in situ cleavage of S–S bonds during the course of hydrothermal treatment. In compound 2, two five‐coordinate zinc centers are connected with carboxylate groups of H2ddca ligands to give a binuclear [Zn2(CO2)4] unit, which are linked by dpe ligands to form a 2D network structure. It is worth noting that compound 2 displays a twofold 2D+2D parallel interpenetration framework containing a polyrotaxane‐like motif. In addition, the thermal stablities and photoluminescence properties of compounds 1 and 2 were also studied.

Coordination Polymers and Clusters Based on the Versatile Mercaptonicotinate Ligands

“…Current studies demonstrate that novel architectures can be fabricated by the employment of two types of d ‐block metal ions or the introduction of nitrogen‐containing auxiliary ligands , , . In contrast to the common ligands, the synthesis of mercaptonicotinate ligand‐based coordination materials involves several kinds of in situ metal/ligand reactions that have been studied by many researchers , , , , . These previously reported materials generally possess unique structures because of the integrated chelating donors which are capable of coordinating with metal ions.…”

“…On the contrary, the facile cleavage of a disulfide bond can bring about the thiolate ligands (reaction type b). By employing in situ ligand reactions, three novel coordination polymers based on mercaptonicotinate ligands were obtained , , . Interestingly, all of the reported structures involved in the in situ cleavage of a disulfide bond were prepared under hydro‐ or solvothermal conditions within the temperature range of 120–160 °C.…”