In situ formation of an unprecedented 3D microporous CuCN coordination polymer based on a semirigid tetrahedral linker

► An unprecedented triply-interpenetrating 3D coordination polymer [Cu4(CN)4(tpom)]n with ths-z topology. ► It was formed by in situ generation of CN from acetonitrile. ► It exhibits relatively high thermal stability and weak photoluminescent emissions at RT. ► It selectively adsorbs 0.8 wt% H2 at 77 K and 1 atm.