Triazinyl-imidazole polyamide network as an efficient multi-hydrogen bond donor catalyst for additive-free CO2 cycloaddition

A single-component synergistic catalytic system, in which multiple active sites act on a substrate with minimal energy input and promote efficient conversion of the substrate, is considered to be the most advanced technology for simulating enzyme catalytic reaction. The design principles of this technology are the driving force behind the pursuit of cost-effectiveness in industrial production, but the challenges remain formidable. Herein, three periodic mesoporous polyamides with triazine-derived networks (PMP-TDNs) were prepared via "one-pot" polycondensation, and used as non-metallic catalysts for cycloaddition of CO2 with epoxides without any additives to synthesis cyclic carbonates. The composition and physicochemical properties of PMP-TDNs were evaluated via different analytical methods to explore the crucial factors affecting catalytic activity. Especially, the activity of PMP-TDNs-MI with multiple hydrogen bond donor (HBD) and high-density N basic sites have been tested effectually; the results has demonstrated a superior reactivity for the cycloaddition of CO2 and a wide range of epoxides with reusability. The kinetics and thermodynamics of cycloaddition of CO2 with propylene epoxide by PMP-TDNS-MI were investigated, and the cooperative catalytic mechanism between the versatile active sites of catalyst was revealed based on the experimental results.