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, [Image: see text] , (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 [Image: see text] 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).