Light-induced thermal hysteresis and high-spin low-spin domain formation evidenced by optical microscopy in a spin-crossover single crystal

Interface versus Bulk Light-Induced Switching in Spin-Crossover Molecular Ultrathin Films Adsorbed on a Metallic Surface

“…Accessing under light excitation at low temperature a state with more molecules in the LS state, compared to the low temperature phase, has been reported in the literature in the case of hidden structural phases. − Our results are not comparable as (i) we are using visible light and not infrared to induce this anomalous light effect, (ii) scanning tunneling microscopy measurements never provided evidence for structural phase transition under visible light, and (iii) the photoswitching occurs randomly in the molecular network without showing any spin-state organization . It thus seems unlikely that our system can evolve under light at low temperature to a hidden phase.…”

Exploring the influence of counterions on a hysteretic spin-transition in isomorphous iron(ii) complex salts

“…55 Hence, [Fe(bpp) 2 ] 2+ complexes with ϕ ≤ 172° are generally less likely to exhibit SCO below room temperature. 54 However, at 120–150 K ϕ in phase C of 2a [167.62(7)°] 22 and 2b [168.09(9)°] differ by only 4 σ , and are essentially equal crystallographically. Hence the molecular structure in phase C cannot, by itself, explain the inactivity of 1b towards SCO.…”

“…Producing new SCO materials to meet those specifications is still a challenging goal of molecular design and crystal engineering. [19][20][21] More fundamentally, SCO materials are useful mechanistic models of phase transitions in molecular crystals, at the macroscopic 22 and atomistic levels. 23,24 SCO transitions exhibiting wide thermal hysteresis have particular interest.…”

Spin Crossover Coordination Polymers with Pyridine-Like Modification through Selective Guest Molecules

“…From every saved image, we can extract the optical density (OD), defined as O D = log ⁡ 10 true( I normali normaln normalc normali normald normale normaln normalt I normalt normalr normala normaln normals normalm normali normalt normalt normale normald true) where I incident corresponds to the bright field intensity while I transmitted corresponds to the intensity of the transmitted light through the single crystal. The OD which is the key parameter of the OM data analysis (recorded images) directly relates to the HS fraction, n HS , of the single crystal, corresponding to the fraction of metal ions in the HS state, through the relation: n H S = ⟨ O D false( x , y false) ⟩ − O D L S O D H S − O D L S where OD HS and OD LS are respectively the OD values in the HS and LS states and ⟨OD( x , y )⟩ is the spatially averaged optical density over the crystal at given temperature, T . In addition, each image of the experimental OM data was split into three OD components: red, green, and blue, depending on the single crystal thickness and color.…”

“…I incident corresponds to the bright field intensity while I transmitted corresponds to the intensity of the transmitted light through the single crystal. The OD which is the key parameter of the OM data analysis (recorded images) directly relates to the HS fraction, n HS , of the single crystal, corresponding to the fraction of metal ions in the HS state, through the relation:48 …”