Control of pore structure by the solvent effect for efficient ethane/ethylene separation

•A family of C2H6-selective MOFs were prepared through the strategy of crystal engineering.•Co-9-ina exhibits ultra-high C2H6/C2H4 selectivity of 2.69 at 100 kPa and 298 K.•Excellent thermal and chemical stability.•High purity of C2H4 can be produced under ambient conditions in one step.