Construction of polynuclear lanthanide (Ln = DyIII, TbIII, and NdIII) cage complexes using pyridine–pyrazole-based ligands: versatile molecular topologies and SMM behavior

Bala, Sukhen; Bishwas, Mousumi Sen; Pramanik, Bhaskar; Khanra, Sumit; Fromm, Katharina M.; Poddar, Pankaj; Mondal, Raju

doi:10.1021/acs.inorgchem.5b00334

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Construction of polynuclear lanthanide (Ln = Dy^III, Tb^III, and Nd^III) cage complexes using pyridine–pyrazole-based ligands: versatile molecular topologies and SMM behavior

Bala, Sukhen Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata, India
Bishwas, Mousumi Sen Physical & Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune, India
Pramanik, Bhaskar Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, India
Khanra, Sumit Department of Chemical Sciences, Indian Institute of Science Education and Research, Kolkata, Mohanpur, India
Fromm, Katharina M. Department of Chemistry, University of Fribourg, Switzerland
Poddar, Pankaj Physical & Materials Chemistry Division, CSIR-National Chemical Laboratory, Pune, India
Mondal, Raju Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Kolkata, India

08.09.2015

Published in:

Inorganic Chemistry. - 2015, vol. 54, no. 17, p. 8197–8206

English Employment of two different pyridyl–pyrazolyl-based ligands afforded three octanuclear lanthanide(III) (Ln = Dy, Tb) cage compounds and one hexanuclear neodymium(III) coordination cage, exhibiting versatile molecular architectures including a butterfly core. Relatively less common semirigid pyridyl–pyrazolyl-based asymmetric ligand systems show an interesting trend of forming polynuclear lanthanide cage complexes with different coordination environments around the metal centers. It is noteworthy here that construction of lanthanide complex itself is a challenging task in a ligand system as soft N-donor rich as pyridyl–pyrazol. We report herein some lanthanide complexes using ligand containing only one or two O-donors compare to five N-coordinating sites. The resultant multinuclear lanthanide complexes show interesting magnetic and spectroscopic features originating from different spatial arrangements of the metal ions. Alternating current (ac) susceptibility measurements of the two dysprosium complexes display frequency- and temperature-dependent out-of-phase signals in zero and 0.5 T direct current field, a typical characteristic feature of single-molecule magnet (SMM) behavior, indicating different energy reversal barriers due to different molecular topologies. Another aspect of this work is the occurrence of the not-so-common SMM behavior of the terbium complex, further confirmed by ac susceptibility measurement.

Faculty

Faculté des sciences et de médecine

Department

Département de Chimie

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