posted on 2018-02-20, 18:43authored byAsami Tsukiashi, Manabu Nakaya, Fumiya Kobayashi, Ryo Ohtani, Masaaki Nakamura, Jack M. Harrowfield, Yang Kim, Shinya Hayami
Iron(III) spin-crossover
(SCO) complexes [Fe(qsal)2]BS·MeOH·H2O (1), [Fe(qsal)2](NS)·MeOH (2), [Fe(qnal)2](NS) (3), and [Fe(qnal)2]PS·MeOH·CH2Cl2 (4) (Hqsal, N-(8-quinolinyl)salicylaldimine; Hqnal, N-(8-quinolinyl)-2-hydroxy-1-naphthaldimine; BS, benzenesulfonate;
NS, 1-naphthalenesulfonate; PS, 1-pyrenesulfonate) have been synthesized
and characterized by X-ray structure determinations and temperature-dependent
magnetic susceptibility measurements. The aromatic counteranions BS,
NS, and PS can be used for the tuning of intermolecular coupling through
a variety of weak interactions. All of the complexes show temperature-dependent
SCO behavior. but the light-induced excited spin-state trapping (LIESST)
effect was observed only for 1, 3, and 4 when the samples were illuminated (λ 808 nm) for 1
h at 5 K. In particular, 59% of the LS form of 1 was
converted to the metastable HS state by illumination, equal to the
highest degree of conversion yet known for LIESST in [Fe(qsal)2]+ derivatives. The lack of a LIESST effect for 2 may be due to the relatively limited degree of interaction
between the cations and anions in the lattice, reflected in a much
longer minimum Fe···Fe separation in this complex in
comparison to the others.