Reciprocating Thermal Behavior and Thermometry Studies of Tb3+ and Gd 3+ -Oxamato Single-Ion Magnets

Abstract

Single-ion magnets (SIMs) are prominent candidates for promoting new technologies in quantum information processing (QIP). Herein, we present two isostructural new thermostable up to ~290 ^oC oxamato derivatives, {n-Bu₄N[Ln(H₂edpba)₂]}_n , Ln = Tb³⁺(1) and Gd³⁺ (2) [H ₂edpba²⁻=N,N'-2,2′-ethylenediphenylenebis(oxamate)]. Single-crystal X-ray diffraction reveals that 1-2 are one-dimensional coordination polymers with a ribbon-like structure, and metal centers are eight coordinated with a D _4d symmetry. Cryomagnetic studies disclose the presence of slow magnetic relaxation (SMR) behavior for 1 and 2. For 1, the Raman effect dominates the SMR at zero magnetic field, while Raman, Orbach, and reciprocating thermal behavior (RTB) mechanisms arise at higher fields. Otherwise, RTB was observed at 2 at low field. Solid-state photoluminescent data display a remarkable green luminescence emission, with intense and sharp bands ranging from 480 to 700 nm in the spectra, which are attributed to the ⁵ D₄ → ⁷F_J (J = 6-0) transitions of terbium(III) ions. By monitoring the temperature-dependent lifetime of the ⁵D₄ state following the intensity decay of the emission band attributed to the ⁵D₄ → ⁷ F₅ (546 nm) transition, the complex shows a reasonable thermometric performance with a relative sensitivity of 2.77% K⁻¹ at 448 K. 1 behaves as a zero-field SIM and as a photoluminescent thermometer.