CO2-empowered Spin Transition in an Interdigitated Hofmann Co-ordination Polymer

The increased level of the anthropogenic emission of CO2 urges the development of CO2-responsive materials that can sense and memorize the system’s information and use it as an electronic output. Herein, we report the first case of a CO2-gated reversible spin-state switching in an interdigitated Hofmann-type coordination polymer [FeIIPd(CN)4L2] (1, L = methyl isonicotinate), showing a wide range of temperature (Teq) shift from ~150 K at PCO2 = 0 kPa to ~250 K at PCO2 = 100 kPa. Interestingly, the emergence of a stepped behavior below PCO2 = 10 kPa and overlapping magnetic susceptibility values with no change in the transition temperature (TH) above PCO2 = 10 kPa elucidate the selective stabilization of the LS state under the influence of the CO2 atmosphere. Based on the magnetic response and the phase transition diagram obtained under the respective PCO2, a plausible scenario of the spin-state switching can be inter-preted as 1LS (1LS + 1’LS) (1HS + 1’LS) 1’HS 1HS, where the CO2-free and CO2-encapsulated states are represent-ed as 1, and 1’, respectively. The highly selective CO2 sorption and the magnetic sensitivity based on the varied exter-nal CO2 pressure corroborate a novel and intriguing case for the development of CO2-responsive magnets henceforth.