Strategies for tuning the catalytic activity of zinc complexes in the solvent-free coupling reaction of CO2 and cyclohexene oxide

•In the coupling reaction of CO2 and cyclohexene oxide, the catalytic activity of zinc complexes can be easily tuned.•Triflate ancillary ligands can turn on the catalytic activity of zinc complexes bearing a chelating nitrogen donor ligand.•Zinc complexes bearing triflates can be good catalysts for the ring-expansive carboxylation of cyclohexene oxide with CO2.