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Vela, S.*; Deumal, M.*; Shiga, Motoyuki; Novoa, J.*; Ribas-Arino, J.*
Chemical Science, 6(4), p.2371 - 2381, 2015/04
Times Cited Count：32 Percentile：68.19(Chemistry, Multidisciplinary)The magnetic properties of molecule-based magnets are commonly rationalized by considering only a single nuclear configuration of the system under study, usually X-ray crystal structure. Here, by means of a computational study in which the results obtained using such a static approach and those obtained by explicitly accounting for thermal fluctuations are compared, we uncover that the serious limitations of the static perspective when dealing with magnetic crystals whose radicals undergo wide-amplitude motions. As a proof of concept, these limitations are illustrated for magnetically bistable 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) material. The discovery that a single X-ray structure is not adequate enough to interpret the magnetic properties of TTTA is also expected to be decisive in other organic magnets with dominant exchange interactions propagating through labile 
networks.
Vela, S.*; Mota, F.*; Deumal, M.*; Suizu, Rie*; Shuku, Yoshiaki*; Mizuno, Asato*; Awaga, Kunio*; Shiga, Motoyuki; Novoa, J.*; Ribas-Arino, J.*
Nature Communications (Internet), 5, p.4411_1 - 4411_9, 2014/07
Recent years have witnessed a growing interest in the use of organic radicals as building blocks for bistable materials, i.e. materials that exist in two inter-exchangeable phases under identical thermodynamic conditions. The neutral radical TTTA is a prominent dithiazolyl-based compound because of its spin transition with a hysterisis nature near the room temperature. From ab initio molecular dynamics simulations, it has been evident that this phase transition is driven by the pair exchange dynamics of molecular stacking units accompanied by a significant gain of vibrational entropy.
