Inter-layer magnetic tuning by gas adsorption in -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 CO2, N-2, and O-2 gases in various isostructural layered magnets with a pi-stacked pillared-layer framework, , (M = Co, 1, Fe, 2, Cr, 3; Cp* = eta(5)-C5Me5; 2,3,5,6-F4PhCO2- = 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 CO2 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 CO2 than for O-2 and N-2, due to the CO2-gated transition. While adsorbent 1 with M = Co (S = 0) was an antiferromagnet with T-N = 75 K, 1 & SUP;CO2 was a ferrimagnet with T-C = 76 K, whereas 1 & SUP;N-2 and 1 & SUP;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 CO2, O-2, and N-2 can serve as crucial triggers for the change in magnetism as a function of variable parameter l(trans).