Easy Excited-State Trapping and Record High TTIESST in a Spin-Crossover Polyanionic Fe(II) Trimer.
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(μ-L)6(H2O)6](6-). 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(-1)). 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 TTIESST = 250 K, the highest temperature ever observed for thermal trapping of an excited spin state in a switchable molecular material.
Institute of Chemical Research of Catalonia (ICIQ), Avinguda Paisos Catalans 16, E-43007 Tarragona, Spain.
Verónica
V
Gómez
Institute of Chemical Research of Catalonia (ICIQ), Avinguda Paisos Catalans 16, E-43007 Tarragona, Spain.
Cristina
C
Sáenz de Pipaón
Institute of Chemical Research of Catalonia (ICIQ), Avinguda Paisos Catalans 16, E-43007 Tarragona, Spain.
Pilar
P
Maldonado-Illescas
Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa , 2695-066 Bobadela LRS, Portugal.
João Carlos
JC
Waerenborgh
Institute of Chemical Research of Catalonia (ICIQ), Avinguda Paisos Catalans 16, E-43007 Tarragona, Spain.
Eddy
E
Martin
Institute of Chemical Research of Catalonia (ICIQ), Avinguda Paisos Catalans 16, E-43007 Tarragona, Spain.
Jordi
J
Benet-Buchholz
Institute of Chemical Research of Catalonia (ICIQ), Avinguda Paisos Catalans 16, E-43007 Tarragona, Spain.|Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluis Companys, 23, E-08010 Barcelona, Spain.
José Ramón
JR
Galán-Mascarós