Abstract
The increased anthropogenic emission level of CO(2) urges the development of CO(2)-responsive materials, but is it possible to regulate the inherent electronic properties through weak physisorption of a ubiquitous gas such as CO(2)? Herein, we intended to answer this imperative question by the first case of CO(2)-actuated variable spin-state stabilisation in an interdigitated Hofmann-type coordination polymer [Fe(II)Pd(CN)(4)L(2)] (1, L = methyl isonicotinate), showing a wide shift in transition temperature (T (eq)) from 178 K at P (CO(2)) = 0 kPa to 229 K at P (CO(2)) = 100 kPa. Interestingly, the emergence of a stepped behaviour in the heating process below P (CO(2)) = 10 kPa and overlapping magnetic susceptibility values above P (CO(2)) = 10 kPa elucidate the selective LS state stabilisation solely correlated with the extent of CO(2) accommodation. Based on the magnetic response and phase transition diagrams obtained under respective P (CO(2)) , a plausible scenario of the spin-state switching can be interpreted as (1(ls) + ) → (1(hs) + ) → 1(hs) at P (CO(2)) ≤ 10 kPa, → 1(hs) at 100 kPa < P (CO(2)) ≥ 32 kPa and → → 1(hs) at 100 kPa, where 1 and 1' represent CO(2)-free and CO(2)-encapsulated states, respectively. The cooperative CO(2) sorption with SCO based on the varied CO(2) pressure corroborates a novel case for developing CO(2)-responsive magnetic materials henceforth.