1
|
de Oliveira Maciel JW, Lemes MA, Valdo AK, Rabelo R, Martins FT, Queiroz Maia LJ, de Santana RC, Lloret F, Julve M, Cangussu D. Europium(III), Terbium(III), and Gadolinium(III) Oxamato-Based Coordination Polymers: Visible Luminescence and Slow Magnetic Relaxation. Inorg Chem 2021; 60:6176-6190. [PMID: 33861078 DOI: 10.1021/acs.inorgchem.0c03226] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The reaction of aqueous solutions of EuIII, TbIII, and GdIII ions with Na2Hpcpa [H3pcpa = N-(4-carboxyphenyl)oxamic acid] afforded three new isostructural oxamate-containing lanthanide(III) coordination polymers of general formula {LnIII2(Hpcpa)3(H2O)5·H2O}n [Ln = Eu (1),Tb (2), and Gd(3)]. Their structure is made up of neutral zigzag chains running parallel to the [101] direction where double syn-syn carboxylate(oxamate)-bridged dilanthanide(III) pairs (Ln1 and Ln2) are linked by three Hpcpa2- ligands, one of them with the μ-κ2O,O':κO″ coordination mode and the other two with the μ3-κ2O,O':κO″:κO'''. Additionally, two of those chains are interlinked through hydrogen bonding and π-π type interactions, resulting in a porous structure with channels where water molecules are hosted. The emission properties of 1 and 2 are evaluated as a function of the temperature, exhibiting an emission in red and green, respectively. The external quantum yield for 2 is approximately 7 times that obtained for 1, indicating that the oxamate ligand is a better sensitizer for TbIII ions. The temperature dependence of the dc magnetic properties of 1-3 reveals a different magnetic behavior depending on the nature of the LnIII ion. A continuous decrease of χMT occurs for 1 upon cooling, and finally χMT tends to vanish, as expected for the thermal depopulation of the six magnetic 7FJ excited states (J = 1-6) of the EuIII ion with a nonmagnetic 7F0 ground state. χMT for 2 decreases sharply with decreasing the temperature due to the depopulation of the splitted mJ levels of the 7F7 ground state of the magnetically anisotropic TbIII ion. A very weak antiferromagnetic interaction between the magnetically isotropic GdIII ions across the double carboxylate(oxamate) bridge is responsible for the small decrease of χMT at low temperatures for 3. The dynamic (ac) magnetic properties of 2 and 3 reveal a slow magnetic relaxation with very incipient frequency-dependent χM″ signals below 6.0 K (2) and frequency-dependent χM″ peaks below 10.0 K (3) under nonzero applied dc magnetic fields, being thus new examples of field-induced single molecule magnets (SMMs).
Collapse
Affiliation(s)
| | - Maykon Alves Lemes
- Instituto de Química, Universidade Federal de Goiás, Goiânia, Goiás, Brazil, 74690-900
| | - Ana Karoline Valdo
- Instituto de Química, Universidade Federal de Goiás, Goiânia, Goiás, Brazil, 74690-900.,Instituto Federal de Educação, Ciência e Tecnologia Goiano, Iporá, Goiás, Brazil, 76200-000
| | - Renato Rabelo
- Departament de Química Inorgànica/Instituto de Ciencia Molecular (ICMol), Facultat de Química de la Universitat de València, València, Paterna, Spain, 46980
| | - Felipe Terra Martins
- Instituto de Química, Universidade Federal de Goiás, Goiânia, Goiás, Brazil, 74690-900
| | | | | | - Francesc Lloret
- Departament de Química Inorgànica/Instituto de Ciencia Molecular (ICMol), Facultat de Química de la Universitat de València, València, Paterna, Spain, 46980
| | - Miguel Julve
- Departament de Química Inorgànica/Instituto de Ciencia Molecular (ICMol), Facultat de Química de la Universitat de València, València, Paterna, Spain, 46980
| | - Danielle Cangussu
- Instituto de Química, Universidade Federal de Goiás, Goiânia, Goiás, Brazil, 74690-900
| |
Collapse
|
2
|
Kamenskyi D, Tkáč V, Čižmár E, Khrustalyov V, Kutko K. Magnetic anisotropy in CsGd(MoO 4) 2probed by EPR spectroscopy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:385801. [PMID: 32422625 DOI: 10.1088/1361-648x/ab940b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
Here we report electron paramagnetic resonance (EPR) study of rare-earth paramagnet CsGd(MoO4)2. Multifrequency EPR measurements allowed us to directly probe the splitting of the lowest8S7/2multiplet of Gd3+ion and revealed the rhombic type of single-ion anisotropy. An easy-axis anisotropy approximation with a rhombic distortion of the Gd3+local environment describes obtained EPR spectra and yield energies of8S7/2splitting. Within this model, we discuss the configuration of the lowest Gd3+multiplet, its zero-field splitting, and the anisotropy of magnetic properties in CsGd(MoO4)2. We argue that the zero-field splitting of8S7/2induces a multiple structure of EPR spectra in CsGd(MoO4)2.
Collapse
Affiliation(s)
- D Kamenskyi
- Experimental Physics V, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, 86159 Augsburg, Germany
- Molecular Photoscience Research Center, Kobe University, 657-8501 Kobe, Japan
| | - V Tkáč
- Institute of Physics, P J Šafárik University, Park Angelinum 9, 040 01, Košice, Slovakia
| | - E Čižmár
- Institute of Physics, P J Šafárik University, Park Angelinum 9, 040 01, Košice, Slovakia
| | - V Khrustalyov
- B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine (ILTPE), Nauky Avenue 47, Kharkiv 61103, Ukraine
| | - K Kutko
- B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine (ILTPE), Nauky Avenue 47, Kharkiv 61103, Ukraine
| |
Collapse
|