Hyperfine Interactions

, 239:37 | Cite as

Spin crossover in two 1D Fe(II) polymers with 1,2,4-triazole thiourea building blocks

  • Houria Benaissa
  • Aurelian Rotaru
  • Yann GarciaEmail author
Part of the following topical collections:
  1. Proceedings of the 4th Mediterranean Conference on the Applications of the Mössbauer Effect (MECAME 2018), Zadar, Croatia, 27-31 May 2018


The 1D chain [Fe(Etutrz)3](ClO4)2 ⋅ 1.5H2O (2) (Etutrz = 1-ethyl-3-(4H-1,2,4-triazol-4-yl) thiourea), displays pronounced thermochromism with a purple color at 77 K while the sample is white at 300 K. Investigation of magnetic properties reveal an abrupt spin transition around 227 K. Differential scanning calorimetry studies on cooling display a first order phase transition at around 200 K with an entropy variation of ΔS = 61.3 J mol− 1 K− 1. 57Fe Mössbauer spectroscopy of 2 confirms a complete spin transition with a 100% high-spin population at 300 K (isomer shift δHS = 1.04(1) mm/s, quadrupole splitting ΔEQ = 2.86(2) mm/s). The Fe(II) ions convert to the low-spin state at 78K (δLS = 0.53(2) mm/s). The quadrupole splitting, ΔEQ = 0.29(2) mm/s, confirms the presence of distorted octahedra within the 1D chain. The 1D chain [Fe(Etutrz)3](BF4)2 ⋅2MeOH (1) exhibits a different magnetic behavior with a gradual spin conversion at T1/2 = 221 K, whereas thermochromic properties are maintained.


57Fe Mossbauer spectroscopy Coordination polymers Spin crossover 1D chains Sensors 



We acknowledge support from the Fonds National de la Recherche Scientifique-FNRS (PDR T.0102.15), WBI-Romanian Academy, WBI (stipendium of excellence for H. B.) CNCS-UEFISCDI, project number PN-II-RU-TE-2014-4-2695 (Contract No. 267/01.10.2015) CNFIS-FDI-2018-058 project and COST action CA15128. We thank GFSM for supporting attendance of H.B. to GFSM 2017 (Béni-Mellal) and GFSM 2018 (Bordeaux).


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© Springer Nature Switzerland AG 2018

Authors and Affiliations

  1. 1.Institute of Condensed Matter and NanosciencesUniversité Catholique de LouvainLouvain-la-NeuveBelgium
  2. 2.Department of Electrical Engineering and Computer Science & Research Center MANSiD“Stefan cel Mare” UniversitySuceavaRomania

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