Frontiers in Chemistry (Aug 2021)

Iron(II) Spin Crossover Coordination Polymers Derived From a Redox Active Equatorial Tetrathiafulvalene Schiff-Base Ligand

  • Ya-Ru Qiu,
  • Ya-Ru Qiu,
  • Long Cui,
  • Jing-Yuan Ge,
  • Mohamedally Kurmoo,
  • Mohamedally Kurmoo,
  • Guijun Ma,
  • Jian Su

DOI
https://doi.org/10.3389/fchem.2021.692939
Journal volume & issue
Vol. 9

Abstract

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Two polymorphic FeII coordination polymers [FeIIL (TPPE)0.5] 1) and [(FeII3L3 (TPPE)1.5)] 2), were obtained from a redox-active tetrathiafulvalene (TTF) functionalized ligand [H2L = 2,2’-(((2-(4,5-bis-(methylthio)-1,3-dithiol-2-ylidene)benzo(d) (1,3) dithiole-5,6-diyl)bis-(azanediyl))bis-(meth anylylidene)) (2E,2E')-bis(3-oxobutanoate)] and a highly luminescent connector {TPPE = 1,1,2,2-tetrakis[4-(pyridine-4-yl)phenyl]-ethene}. Complex 1 has a layered structure where the TPPE uses its four diverging pyridines from the TPPE ligand are coordinated by the trans positions to the flat TTF Schiff-base ligand, and complex 2 has an unprecedented catenation of layers within two interpenetrated frameworks. These coordination polymers reserved the redox activity of the TTF unit. Complex 1 shows gradual spin transition behavior without hysteresis. And the fluorescence intensity of TPPE in 1 changes in tandem with the spin crossover (SCO) transition indicating a possible interplay between fluorescence and SCO behavior.

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