Enhanced dielectricity coupled to spin-crossover in a one-dimensional polymer iron(ii) incorporating tetrathiafulvalene

Ya-Ru Qiu; Long Cui; Pei-Yu Cai; Fei Yu; Mohamedally Kurmoo; Chanel F Leong; Deanna M D'Alessandro; Jing-Lin Zuo

doi:10.1039/d0sc02388d

Enhanced dielectricity coupled to spin-crossover in a one-dimensional polymer iron(ii) incorporating tetrathiafulvalene

Chem Sci. 2020 May 27;11(24):6229-6235. doi: 10.1039/d0sc02388d. eCollection 2020 Jun 28.

Authors

Ya-Ru Qiu¹, Long Cui¹, Pei-Yu Cai¹, Fei Yu^{1

2}, Mohamedally Kurmoo^{1

3}, Chanel F Leong⁴, Deanna M D'Alessandro⁴, Jing-Lin Zuo¹

Affiliations

¹ State Key Laboratory of Coordination Chemistry , School of Chemistry and Chemical Engineering , Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210023 , P. R. China . Email: [email protected].
² School of Chemistry and Materials Science , Nanjing University of Information Science and Technology , Nanjing , 210044 , P. R. China.
³ Institut de Chimie de Strasbourg , CNRS-UMR7177 , Université de Strasbourg , 4 rue Blaise Pascal , Strasbourg 67000 , France . Email: [email protected].
⁴ School of Chemistry , The University of Sydney , Sydney , New South Wales 2006 , Australia.

Abstract

In designing multifunctional materials for potential switches that can be used as memory devices, the high-spin (HS) to low-spin (LS) crossover (SCO) one-dimensional polymer, [Fe^II(L)(4,4'-bpy)] _n , was constructed from a designed redox-active tetrathiafulvalene (TTF) functionalized Schiff-base and the ditopic linker 4,4'-bipyridine (bpy). It exhibits an 8 K hysteretic SCO centred at T _1/2 = 325 K which is coupled to changes in its dielectric constant. The crystal structures above and below the transition temperature reveal similar parallel linear ···Fe-bpy-Fe-bpy··· chains displaying expansion of the Fe^II octahedron in the HS state. Density functional theory (DFT) calculations reveal a concerted electronic charge and spin change represented by the Mülliken charge of the Fe and the magnitude and direction of the dipole moment which substantiate the experimental observations.