Co–NC–W and Fe–NC–W Electron‐Transfer Channels for Thermal Bistability in Trimetallic {Fe₆Co₃[W(CN)₈]₆} Cyanido‐Bridged Cluster

Abstract

The design and construction of switchable materials attracts tremendous interest owing to the potential in information storing and processing or molecular sensing. [1][2][3][4] The archetypal examples involve a diversity of Fe II -, [5,6] Fe III - [7] or Co IIbased [8][9][10] spin-crossover (SCO) compounds, Co III/II -catecholate/semiquinone systems, [1,11] as well as d-d bimetallic and sd-d trimetallic cyanide-bridged systems revealing chargetransfer-induced spin transitions (CTIST). [12][13][14][15][16][17][18] Some of these compounds, for example Prussian blue analogues, are particularly promising from the point of view of photoswitching between nonmagnetic and magnetized (that is, T B , T C ) states, owing to magnetic coupling through molecular bridges in discrete species [14,15] and extended networks. [17,18] Such bistability also emerged in the magnetochemistry of octacyanidometalates, exploiting metal-to-metal electron transfer in HS Co II L[W V (CN) 8 ] 3À (L = pyrimidine, 4-methylpyridine) [19,20] or canonical SCO in Fe II L[Nb IV (CN) 8 ] 4À extended networks [21] (L = 4-pyridinealdoxime). A magnetic hysteresis loop with a coercivity of 1-3 T were observed in an optically excited low-temperature metastable phase.

Spin crossover in Hofmann-like coordination polymers. Effect of the axial ligand substituent and its position

“…In these solids, the CN ligands at their N ends can be combined with appropriate organic ligands for tuning the energy splitting between the t 2g and e g orbitals to make possible the HS -LS transition. Of that family of solids, the SCO has been reported for ferrous tetracyanides; [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41] copper(I), 42 silver(I), 43 and gold(I) dicyanides; 44 octacyanides; [45][46][47] nitroprussides, [48][49][50][51][52][53][54][55][56][57][58] and other cyanide-based 3d transition metal coordination polymers. 59,60 We believe that enough qualitative information is available on the SCO in these coordination polymers to rationalize ligand and metal effects in order to design materials with the desired behavior.…”

Site Selectivity for the Spin States and Spin Crossover in Undecanuclear Heterometallic Cyanido-Bridged Clusters

“…1.4 × 2.5 × 2.5 nm ( 4 R / 4 S ), considering the distance between the most remote atoms along three cluster axes. Various metallic core compositions embedded within the same topological scaffold and the related SCO scenarios open a promising route for molecular design toward advanced cocrystal salts involving switchable polynuclear clusters 88 , 89 and molecular hierarchical systems such as heterotrimetallic solid solutions 55 , 56 , 59 , 60 or core–shell composites; 90 the solubility and stability of these forms in various organic solvents might be one of the prerequisites in further research. Moreover, the research on SCO transitions in multisite clusters might provide better characteristics (e.g., larger cooperativity, SCO site speciation, multistep transitions, etc.).…”

Oxygen-Independent Radiodynamic Therapy: Radiation-Boosted Chemodynamics for Reprogramming the Tumor Immune Environment and Enhancing Antitumor Immune Response

“…17 The metal-to-metal charge transfer (MMCT) of W and Fe have been reported previously under high temperature. 18,19 And the W based POM has been verified to be excited by X-ray as an effective radiosensitizer. 20 Therefore, we hypothesize that POMs that contain W and Fe ions have the potential for radiation boosted chemodynamics.…”

“…In the present study, we synthesized the polyoxometalate K 21 Na 8 [KFe 12 (OH) 18 (α-1,2,3-P 2 W 15 O 56 ) 4 ]•70H 2 O (referred to as Fe 12 -POM) involved in the formation of a "super" tetrahedral structure. This cluster consisted of four P 2 W 15 units acting as X-ray energy antennas, transferring energy to the Fe 3 core, which served as an energy and electron receptor.…”