Four-step spin-crossover in an oxamide-decorated metal-organic framework

Four-step electron transfer coupled spin transition in a cyano-bridged [Fe2Co2] square complex

The design of molecular functional materials with multi-step magnetic transitions has attracted considerable attention. However, the development of such materials is still infrequent and challenging. Here, a cyano-bridged square Prussian blue complex that exhibits a thermally induced four-step electron transfer coupled spin transition (ETCST) is reported. The magnetic and spectroscopic analyses confirm this multi-step transition. Variable-temperature infrared spectrum suggested the electronic structures in each phase and a four-step transition model is proposed.

Synergetic Responses of Multiple Functions Induced by Phase Transition in Molecular Materials

Materials that integrate magnetism, electricity and luminescence can not only improve the operational efficiency of devices, but also potentially generate new functions through their coupling. Therefore, multifunctional synergistic effects have broad application prospects in fields such as optoelectronic devices, information storage and processing, and quantum computing. However, in the research field of molecular materials, there are few reports on the synergistic multifunctional properties. The main reason is that there is insufficient awareness of how to obtain such material. In this brief review, we summarized the molecular materials with this characteristic. The structural phase transition of substances will cause changes in their physical properties, as the electronic configurations of the active unit in different structural phases are different. Therefore, we will classify and describe the multifunctional synergistic complexes based on the structural factors that cause the first-order phase transition of the complexes. This enables us to quickly screen complexes with synergistic responses to these properties through structural phase transitions, providing ideas for studying the synergistic response of physical properties in molecular materials.

Guest-triggered "Soma-Iwamoto-type" penetration complex {Fe(4-methoxypyrimidine)2[M(CN)2]2}·Guest (M = Ag, Au)

Many laboratories have performed extensive studies on the spin-crossover (SCO) phenomenon. Herein, we synthesized novel "Soma-Iwamoto type" complexes containing a 4-methoxypyrimidine (4-MeOPmd) ligand, i.e., {Fe(4-MeOPmd)₂[Ag(CN)₂]₂} (1Ag), {Fe(4-MeOPmd)₂[Au(CN)₂]₂} (1Au), and {Fe(4-MeOPmd)₂[Ag(CN)₂]₂·0.25(4-MeOPmd)} (1Ag·0.25G). Moreover, we synthesized a 4,6-dimethoxypyrimidine (4,6-diMeOPmd) clathrate complex, i.e., {Fe(4-MeOPmd)₂[Ag(CN)₂]₂·0.25(4,6-diMeOPmd)} (2Ag·0.25G) and {Fe(4-MeOPmd)₂[Au(CN)₂]₂·0.25(4,6-diMeOPmd)} (2Au·0.25G). Some of these complexes, i.e., 1Ag·0.25G, 2Ag·0.25G, and 2Au·0.25G, demonstrated penetrated structures, which are very interesting given that they have rarely been reported to date. 1Au and 1Ag did not show the SCO phenomenon, 1Ag·0.25G showed a gradual multi-step SCO phenomenon, and 2Au·0.25G and 2Ag·0.25G showed an abrupt half SCO phenomenon.

Spin-Crossover Behaviors of Iron(II) Complexes Bearing Halogen Ligands in Solid State and Solution

Numerous Fe(II) spin-crossover (SCO) compounds have been developed in the past decades, while the reports on the SCO materials with halogen atoms acting as coordinating ligands remain rare. In this study, we synthesize three iron(II) halide complexes with a general formula of [Fe^II(Py5Me₂)X]⁺ (Py5Me₂ = 2,6-bis[1,1-bis(2-pyridyl)ethyl]pyridine, X = Cl^- or Br^-) that undergo complete SCO transitions at near room temperature. The SCO properties of these compounds are investigated in detail by magnetic measurements, variable-temperature single-crystal X-ray diffractions, and Mössbauer spectra analyses. Because of the good stability of the coordination structures and suitable ligand-field strength, these compounds show robust spin transitions in both solid state and solution.

2D/3D spin crossover porous coordination polymers based on isomeric tetrapyridyl benzene ligands

By employing cyanoborohydride and isomeric tetrapyridyl benzene ligands, a new three-dimensional (3D) [Fe(3-tpb)(NCBH3)2] (1·2H2O, 3-tpb = 1,2,4,5-tetra(pyridin-3-yl)benzene) and a two-dimensional (2D) [Fe(4-tpb)(NCBH3)2] (2·2-NapSMe and 2·H2O·3DMF, 4-tpb = 1,2,4,5-tetra(pyridin-4-yl)benzene, 2-NapSMe =...