Lanthanide‐Based Layer‐Type Two‐Dimensional Coordination Polymers Featuring Slow Magnetic Relaxation, Magnetocaloric Effect and Proton Conductivity

• Published in: Chemistry, an Asian journal an Asian journal, 2019-10, Vol.14 (20), p.3702-3711
• Main Authors: Bera, Siba Prasad, Mondal, Arpan, Konar, Sanjit
• Format: Article
• Language: English
• Subjects: Chemistry; Coordination polymers; Dysprosium; Erbium; High temperature; lanthanides; Magnetic induction; Magnetic properties; magnetic refrigeration; Magnetic relaxation; Nodes; proton conductivity; Protons; Relative humidity; Relaxation time; single-molecule magnets; Tensors; Two dimensional analysis
• ISSN: 1861-4728; 1861-471X
• DOI: 10.1002/asia.201900842

Three lanthanide‐based two‐dimensional (2D) coordination polymers (CPs), [Ln(L)(H2O)2]n, {H3L=(HO)2P(O)CH2CO2H; Ln=Dy3+ (CP 1), Er3+ (CP 2)} and [{Gd2(L)2(H2O)3}.H2O]n, (CP 3) were hydrothermally synthesized using phosphonoacetic acid as a linker. Structural features revealed that the dinuclear Ln3+ nodes were present in the 2D sheet of CP 1 and CP 2 while in the case of CP 3, nodes were further connected to each other forming a chain‐type arrangement throughout the network. The magnetic studies show field‐induced slow magnetic relaxation property in CP 1 and CP 2 with Ueff values of 72 K (relaxation time, τ0=3.05×10−7 s) and 38.42 K (relaxation time, τ0=4.60×10−8 s) respectively. Ab‐initio calculations suggest that the g tensor of Kramers doublet of the lanthanide ion (Dy3+ and Er3+) is strongly axial in nature which reflects in the slow magnetic relaxation behavior of both CPs. CP 3 exhibits a significant magnetocaloric effect with −ΔSm=49.29 J kg−1 K−1, one of the highest value among the reported 2D CPs. Moreover, impedance analysis of all the CPs show high proton conductivity with values of 1.13×10−6 S cm−1, 2.73×10−3 S cm−1 and 2, 6.27×10−6 S cm−1 for CPs 1–3, respectively, at high temperature (>75 °C) and maximum 95 % relative humidity (RH). Three lanthanide‐based 2D coordination networks with dinuclear nodes and chain‐type arrangement of the metal ions have been investigated for field‐induced slow magnetic relaxation, magnetocaloric effect, and proton conductivity.