Reciprocating Thermal Behavior and Thermometry Studies of Tb3+ and Gd 3+ -Oxamato Single-Ion Magnets
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Cleber R Araujo Junior , Luana M Murad , Rafael V Perrella , Willian X. C. Oliveira , Carlos Basílio Pinheiro , Thais F Ramos , Patricia Patricio , Emerson F. Pedroso , Wallace C. Nunes , Pablo Rafael Trajano Ribeiro , Diego Muraca , Fernando Fabris , Marcelo Knobel , Fernando Aparecido Sigoli and Cynthia L. M. Pereira
First published on 24th September 2025
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 → 7FJ (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.