Alkenone-enol-alkenone [2+2+2] Cyclotrimerization Producing Functional Coordination Polymers with Excellent Adsorption Performance

[2+2+2] cycloaddition reactions are one of the most elegant routes for the construction of six-membered rings. Here, we report initially the alkenone-enol-alkenone [2+2+2] cycloaddition reaction and introduce the cycloaddition into the system of in situbuilding complexes, where three novel coordination polymers (CPs) with functional groups, namely {[CdCl2(L1)]}n(1), {[CdCl2(L2)]}n(2), and {[CdCl2(L3)]}n(3), have been obtained. Particularly, the new 1,2,3,4,5-pentasubtituted cyclohexanols ligands L1, L2, and L3 are created from the starting chalcone derivatives via the [2+2+2] cyclotrimerization. Cadmium chloride not only plays the role of constructing CPs but also acts as a catalyst to promote the cycloaddition reaction. In addition, benefiting from numerous exposed carbonyl and hydroxyl function groups, CPs 1–3are applied to the adsorptive removal of dyes (congo red (CR) and methyl orange (MO)) from aqueous solutions. As a result, 1–3show excellent dye adsorption capacity. 1exhibits maximum CR adsorption capacity of 485.4 mg g–1, and 3has ultrahigh MO uptake capacity of 492.6 mg g–1. Experimental results suggest that the dye removal effect derives from the interactions between dye molecules and the exposed carbonyl and hydroxyl groups.