Coordination-Induced Spin-State Memory via Cooperative binding

Abstract

Molecular magnetic units capable of Coordination-Induced Spin-State Switching (CISSS) are embedded within a soft porous crystal (SPC) framework, enabling cooperative and bistable spin-state memory at room temperature. The transformation between the open-pore high-spin state [Ni₂(hbih)(py)₆]·py·H₂O (CN6) and the closed-pore low-spin state [Ni₂(hbih)(py)₂] (CN4) exhibits pronounced magnetic hysteresis. Crucially, Hill analysis yields a coefficient (n ≈ 12), quantitatively evidencing strong cooperativity in guest-induced switching, underlying a large kinetic barrier (10,726 cm⁻¹ and 13,610 cm⁻¹ for association and dissociation, respectively). Such high cooperativity and the associated energy barriers enable photo-thermal manipulation for reversible, inkless, and non-contact information printing, affording a storage half-life of 289 days. This study highlights a bottom-up strategy to realize framework-level cooperative bistability in molecular magnetic materials through the synergy of CISSS chemistry and SPC architectures.