Two interpenetrated diamondoid coordination networks, Dia-4-M (M= Ni and Co), are synthesized. Both materials exhibit preferential binding of C2H6 over C2H4, because C2H6 molecules can be well accommodated within the pores through stronger host–guest interactions. Such C2H6-selective porous materials not only exhibit decent C2H6/C2H4 selectivity but also display ultra-high C2H6 uptake. Display omitted •Reversed selective C2H6/C2H4 separation was due to the enhanced host–guest interaction.•Dia-4-Co exhibits ultra-high C2H6 uptake (103 cm3 g−1).•Exceptional recyclability for Dia-4-Co and Dia-4-Ni.•High purity (99.9%) of C2H4 can be produced in one step under ambient conditions. The separation of ethane (C2H6) from ethylene (C2H4) is one of the most challenging and important tasks in chemical industry. Herein we report two interpenetrated diamondoid (dia) coordination networks, Dia-4-M M(pba)2 (pba = 4-(4-pyridyl)benzoate); M = Ni or Co), that can directly capture ethane from ethane-ethylene mixtures with reverse C2H6/C2H4 separation. Both materials not only exhibit ultra-high C2H6 uptake (100 cm3 g−1 for Dia-4-Ni; 103 cm3 g−1 for Dia-4-Co) but also display good C2H6/C2H4 selectivity (1.76 for Dia-4-Ni; 2.04 for Dia-4-Co). Such C2H6/C2H4 separation performance was confirmed by dynamic breakthrough experiments. Dia-4-M could extract low concentrated of C2H6 from C2H6/C2H4 mixture (v(C2H6)/v(C2H4) = 1:9 and 1:15) and produce high purity (99.9%) of C2H4 under ambient conditions. The mechanism for selective C2H6/C2H4 separation was clarified through Grand Canonical Monte Carlo (GCMC) simulations and Density functional theory (DFT) calculations. Overall, this research demonstrates that Dia-4-M has a significant potential as effective C2H6-selective adsorbents for the purification of ethylene in practice.