Room‐Temperature Photoinduced Electron Transfer in a Prussian Blue Analogue under Hydrostatic Pressure

Abstract

The high technological demand for system miniaturization led to the "top-down" approach of the nanosciences. As the size of technological components progressively reaches that of the molecular level, the idea to use materials exhibiting intrinsically molecular properties becomes more and more appealing. [1][2][3][4][5][6] The use of light is one of the most promising ways to control various physical properties of organic [1] , metalorganic, and coordination compounds [2a,c-e, 3, 4, 6c] and this type of control could have future applications in the elaboration of molecular memories and switching devices.Among these compounds, coordination compounds that exhibit photoinduced charge transfers and/or spin transitions involving the metallic d orbitals can have the following attributes: stability over successive cycles, short addressing times associated with such electronic transitions, full reversibility, and chemical stability. Although the photomagnetic properties of these compounds appear to have great potential for technological applications, the low relaxation temperature of the metastable state and therefore the low working temperature strongly limits their use in practical applications. To date, very few methods for enabling the photomagnetic effect to function at room temperature have been proposed: in 2002 Shimamoto et al. discovered that the low-temperature phase could be phototransformed into the high-temperature phase within the broad thermal hysteresis loop of a sodium derivative of a CoFe Prussian blue analogue (PBA); [7] later, Bozdag et al. reported a different kind of photomagnetic effect, which probably originates from a photoinduced structural distortion.[8] Herein, we demonstrate, using synchrotronbased energy-dispersive X-ray absorption spectroscopy, that a room-temperature photoinduced

Coherent structural trapping through wave packet dispersion during photoinduced spin state switching

“…The obtained initial XANES amplitudes of the intermediate match the expected formal Fe 3+ MLCT spectrum ( Fig. 1d ) approximated by shifting the LS spectrum by 1 eV, I MLCT /I LS = I LS (E+ 1 eV )/I LS (E) , as suggested by previous XANES studies on similar compounds 17 18 . The lifetime τ MLCT =120(10) fs of this clear fingerprint of the MLCT intermediate is compatible with the lifetime found by XES 5 .…”

Oriented assembly of anisotropic nanoparticles into frame-like superstructures

“…The Co-H 2 O sites act at the same time both as electron donor toward the Fe III sites (electron acceptors) and as proton donor toward the hydroxyl ions (proton acceptors). This type of electron transfer in PBAs which is mediated by chemical modification (specifically, ion insertion) has been reported before ( 46 , 53 ), and is distinct from other means using external stimuli, such as photoradiation ( 44 ), temperature ( 48 ), and pressure ( 49 ).…”

“…Toward this goal, we choose Prussian blue analogs (PBAs) as the target materials in view of the limited success in exploiting these PBA-type materials for colloidal assembly and their transformation versatility toward functional materials with retainable structures ( 41 – 43 ). Besides, the Co-Fe combination is one of the most important PBA-type materials with switchable magnetic and electronic properties ( 44 – 49 ), which enables promising application in catalysis to be realized ( 50 ). Comprehensive investigations reveal that phase transition, epitaxial growth, confined assembly, and OA are involved in the formation process for the superstructures reported here.…”

Influence of the number of alkali cation on the photo-induced CoIIIFeII↔CoIIBordage1, Bleuzen2 2020Radiation Physics and ChemistrySelf Cite7060View full textAdd to dashboardCite

“…Some of them indeed present a photo-induced (PI) Co III Fe II →Co II Fe III charge transfer depending on the nature and number of alkali cations inserted in the unit cell (Escax et al, 2003). For instance, CoFe PBA without alkali cation presents a Co III Fe II →Co II Fe III PI charge transfer at room temperature (RT) and 2Gpa (Cafun et al, 2012). Nevertheless, no PI charge transfer is observed at ambient pressure whatever the temperature, neither in the case of 4 alkali cations per unit cell (Bleuzen et al, 2000).…”