Switching the Multiple Function Channels in 2D Hofmann-Type Coordination Polymers

The modulation of multifunctional molecular materials by utilizing the stimuli-responsive spin crossover (SCO) has attracted considerable research interest due to its potential applications in information storage and smart switching devices. However, the complexity of achieving the integration and interconnection of multiple functions constitutes a formidable challenge. Herein, we present a pair of 2D Fe^II-based Hofmann-type coordination polymers (HTCPs), namely {Fe^II(aep)₂[Ag^I(CN)₂]₂}·0.3DMF (<b>1</b>) and {Fe^II(avp)₂[Ag^I(CN)₂]₂} (<b>2</b>), using fluorescence ligands 4-[2-(9-anthracenyl)ethynyl]pyridine (aep) and 4-[2-(9-anthryl)vinyl]pyridine (avp), respectively. Both complexes exhibit one-step SCO, with transition temperatures of 216 K for complex <b>1</b> and 255 K for complex <b>2</b>. Their dielectric properties align well with the observed magnetic behaviors, demonstrating the dielectric transition process caused by the change of spin state. A variable-temperature fluorescence study reveals the coexistence of SCO and luminescent properties in both complexes, with a remarkable synergistic coupling observed in complex <b>2</b> due to the shorter distance between the SCO centers and the fluorophore. These findings underscore the potential of HTCPs as a promising platform for modulating multiple functions. By manipulating their spin states through external stimuli, SCO materials will promisingly advance the development of next-generation molecule-based sensors and devices.