Synthesis of (BiSe) 1+δ (Bi 2 Se 3 ) 1+γ (BiSe) 1+δ TiSe 2 by Directed Self-Assembly of a Designed Precursor

Lygo, Alexander C.; Wood, Suzannah R.; Ditto, Jeffrey; Johnson, David C.

doi:10.1021/acs.chemmater.8b04229

Abstract Co‐crystallization of the spin‐crossover (SCO) cationic complex, [Fe(1‐bpp)₂]²⁺(1‐bpp=2,6‐bis(pyrazol‐1‐yl)pyridine) with fractionally charged organic anion TCNQ^δ−(0<δ<1) afforded hybrid materials [Fe(1‐bpp)₂](TCNQ)_3.5 ⋅ 3.5MeCN (1) and [Fe(1‐bpp)₂](TCNQ)₄ ⋅ 4DCE (2), where TCNQ=7,7,8,8‐tetracyanoquinodimethane, MeCN=acetonitrile, and DCE=1,2‐dichloroethane. Both materials exhibit semiconducting behavior, with the room‐temperature conductivity values of 1.1×10⁻⁴ S/cm and 1.7×10⁻³ S/cm, respectively. The magnetic behavior of both complexes exhibits strong dependence on the content of the interstitial solvent. Complex1undergoes a gradual temperature‐driven SCO, with the midpoint temperature ofT_1/2=234 K. The partial solvent loss by1leads to the increase in theT_1/2value while complete desolvation renders the material high‐spin (HS) in the entire studied temperature range. In the case of2, the solvated complex shows a gradual SCO withT_1/2=166 K only when covered with a mother liquid, while the facile loss of interstitial solvent, even at room temperature, leads to the HS‐only behavior.

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