Reciprocating thermal behavior and thermometry studies of Tb³⁺- and Gd³⁺-oxamato single-ion magnets

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Araujo Junior, Cleber R. ; Murad, Luana M. ; Perrella, Rafael V. ; Oliveira, Willian X. C. ; Pinheiro, Carlos B. ; Ramos, Thais F. ; Patricio, Patricia S. O. ; Pedroso, Emerson F. ; Nunes, Wallace C. ; Ribeiro, Pablo R. T. ; Muraca, Diego ; Fabris, Fernando ; Knobel, Marcelo ; Sigoli, Fernando A. ; Pereira, Cynthia L. M.

• Document type: Journal article
• Source: INORGANIC CHEMISTRY FRONTIERS; v. N/A, p. 17-pg., 2025-09-24.

Abstract

Single-ion magnets (SIMs) are prominent candidates for promoting new technologies in quantum information processing (QIP). Herein, we present two new isostructural oxamato derivatives, namely, {n-Bu4N[Ln(H2edpba)2]}n, Ln = Tb3+ (1) and Gd3+ (2) [H2edpba2- = N,N '-2,2 '-ethylenediphenylenebis(oxamate)], that are thermostable up to similar to 290 degrees C. Single-crystal X-ray diffraction reveals that 1 and 2 are one-dimensional coordination polymers with a ribbon-like structure, and their metal centers are eight-coordinated with a D4d 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 a zero magnetic field, while Raman, Orbach, and reciprocating thermal behavior (RTB) mechanisms arise at higher fields. Conversely, RTB and the bottleneck effect were observed at 2. 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 5D4 -> 7FJ (J = 6-0) transitions of terbium(iii) ions. By monitoring the temperature-dependent lifetime of the 5D4 state after the intensity decay of the emission band attributed to the 5D4 -> 7F5 (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. (AU)

• FAPESP's process: 23/17024-1 - EMU: Acquisition of compressor, chiller and gas for helium liquefying system in the Cryogenic Workshop of IFGW
• Grantee: Odilon Divino Damasceno Couto Júnior
• Support Opportunities: Research Infrastructure Program - Small Medium Sized
• FAPESP's process: 21/08111-2 - Development of rare earth based light converters: luminescent markers, optical sensors, and amplifiers
• Grantee: Hermi Felinto de Brito
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 24/00198-0 - Hierarchical luminescent core@shell nanocrystals based on rare earth fluorides for intracellular temperature sensing and imaging
• Grantee: Rafael Vieira Perrella
• Support Opportunities: Scholarships in Brazil - Post-Doctoral