Inter-layer magnetic tuning by gas adsorption in π-stacked pillared-layer framework magnets.

Magnetism of layered magnets depends on the inter-layer through-space magnetic interactions ( J NNNI ). Using guest sorption to address inter-layer pores in bulk-layered magnets is an efficient approach to magnetism control because the guest-delicate inter-layer distance ( l trans ) is a variable parameter for modulating J NNNI . Herein, we demonstrated magnetic changes induced by the adsorption of CO 2 , N 2 , and O 2 gases in various isostructural layered magnets with a π-stacked pillared-layer framework, , (M = Co, 1, Fe, 2, Cr, 3; Cp* = η 5 -C 5 Me 5 ; 2,3,5,6-F 4 PhCO 2 - = 2,3,5,6-tetrafluorobenzoate; TCNQ = 7,7,8,8-tetracyano- p -quinodimethane). Each compound had almost identical adsorption capability for the three types of gases; only CO 2 adsorption was found to have a gated profile. A breathing-like structural modulation involving the extension of l trans occurred after the insertion of gases into the isolated pores between the [Ru 2 ] 2 -TCNQ ferrimagnetic layers, which is more significant for CO 2 than for O 2 and N 2 , due to the CO 2 -gated transition. While adsorbent 1 with M = Co ( S = 0) was an antiferromagnet with T N = 75 K, 1⊃CO 2 was a ferrimagnet with T C = 76 K, whereas 1⊃N 2 and 1⊃O 2 were antiferromagnets with T N = 68 K. The guest-insertion effect was similarly confirmed in 2 and 3, and was characteristically dependent on the type of sandwiched spin in as M = Fe ( S = 1/2) and Cr ( S = 3/2), respectively. This study reveals that common gases such as CO 2 , O 2 , and N 2 can serve as crucial triggers for the change in magnetism as a function of variable parameter l trans .