Two-Dimensional Spin-Crossover Molecular Solid Solutions with Tunable Transition Temperatures across 90 K

Abstract

Spin-crossover (SCO) materials exhibit remarkable potential as bistable switches in molecular devices. However, the spin transition temperatures (T c ) of known compounds are unable to cover the entire ambient temperature spectrum, largely limiting their practical utility. This study reports an exemplary two-or Cl, x = 0 to 1), in which the adjacent layers are adhered via hydrogen bonding. Notably, the T c of this system can be fine-tuned across 90 K (227− 316 K) in a linear manner by modulating the fraction x of the L F ligand. Elevating x results in strengthened hydrogen bonding between adjacent layers, which leads to enhanced intermolecular interactions between adjacent SCO molecules. Single-crystal diffraction analysis and periodic density functional theory calculations revealed that such a special kind of alteration in interlayer interactions strengthens the Fe III N 2 O 2 S 2 ligand field and corresponding SCO energy barrier, consequently resulting in increased T c . This work provides a new pathway for tuning the T c of SCO materials through delicate manipulation of molecular interactions, which could expand the application of bistable molecular solids to a much wider temperature regime.

Accurate Prediction of the Magnetic Ordering Temperature of Ultralow-Temperature Magnetic Refrigerants

“…The interlamellar bridge of carbonate or μ 2 –O carboxylate generally shows negligible antiferromagnetic coupling, indicating that the magnetic interaction in 1 is dominated by the magnetic exchange in the 2D layer. Therefore, the extremely weak antiferromagnetic interaction in 1 can be mainly assigned to the competition between the antiferromagnetic and ferromagnetic exchange interactions. − …”

Activating a high-spin iron(ii) complex to thermal spin-crossover with an inert non-isomorphous molecular dopant

“…38–55 We, and others, have also investigated doping as a way to introduce new functionality into SCO materials. 42,55–60 Two examples are particularly relevant to this work, where doping a complex into a host lattice changes its spin state properties. First, low-spin [Fe(terpy) 2 ][ClO 4 ] 2 (terpy = 2,2′:6′,2′′-terpyridine) is activated towards light-induced spin state trapping 38 at low temperatures when doped into isomorphous [Mn(terpy) 2 ][ClO 4 ] 2 .…”

Constructing Alkyl Chain Modified FeII Spin Crossover Complexes through Complementary Pair Strategy

“…[5] Consequently, Fe II -based SCO materials are believed promisingly in applications of information storage media, display devices, and molecular switches. [6] In pursuit of controlling SCO behavior, a myriad of strategies have been explored, ranging from the application of external physical stimuli such as light, [7] pressure, [8] temperature, [9] and electromagnetic fields, [10] to chemical approaches involving the manipulation of the first coordination sphere, the electronic influence of substituents, [11] the presence of co-crystallized solvent molecules, [12] and the selection of counterions. [13] Despite these advancements, the precise manipulation of transition temperatures and a thorough understanding of the SCO-structural relationship remain critical challenges, underscored by the high sensitivity of SCO properties to environments.…”