Easy Excited-State Trapping and Record High TTIESST in a Spin-Crossover Polyanionic FeII Trimer

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• 作者：Ver贸nica G贸mez ; Cristina S谩enz de Pipa贸n ; Pilar Maldonado-Illescas ; Jo茫o Carlos Waerenborgh ; Eddy Martin ; Jordi Benet-Buchholz ; Jos茅 Ram贸n Gal谩n-Mascar贸s
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：September 23, 2015
• 年：2015
• 卷：137
• 期：37
• 页码：11924-11927
• 全文大小：303K
• ISSN：1520-5126

文摘

Reaction of the polysulfonated triazole ligand L = 4-(1,2,4-triazol-4-yl)ethanedisulfonate) with iron(II) salts in water yields the trimeric species [Fe₃(渭-L)₆(H₂O)₆]^{6鈥?/sup>. This polyanion, as the dimethylammonium salt, shows a thermally induced spin transition above room temperature for the central Fe position in the trimer with a large hysteresis cycle (>85 K) and remarkably slow dynamics. This allows easy quenching of the metastable high-spin (HS) state via gradual cooling (5 K min鈥?). Once it is trapped, the HS state remains metastable. Thermal energy is not able to promote relaxation into the low-spin ground state below 215 K, with a characteristic T_TIESST = 250 K, the highest temperature ever observed for thermal trapping of an excited spin state in a switchable molecular material.}