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Exploring Tuning of Structural and Magnetic Properties by Modification of Ancillary β-Diketonate Co-ligands in a Family of Near-Linear Tetranuclear DyIII Complexes

Research paper by Joydev Acharya, Sourav Biswas, Jan van Leusen, Pawan Kumar, Vierandra Kumar, Ramakirushnan Suriya Narayanan, Paul Kögerler, Vadapalli Chandrasekhar

Indexed on: 14 Jun '18Published on: 01 Jun '18Published in: Crystal Growth & Design



Abstract

Three, near-linear tetranuclear DyIII complexes have been synthesized and characterized. By varying the electronic and steric demand of the ancillary β-diketonate co-ligands, subtle changes in the geometry around the DyIII centers have been achieved. Correlation of these structural changes with the magnetic behavior of the complexes has been studied.Three tetranuclear DyIII complexes, [Dy4(LH)2(CH3OH)4(acac)6] (1), [Dy4(LH)2(CH3OH)4(hmacac)6]·2CH3OH (2), and [Dy4(LH)2(CH3OH)4(dpacac)6]·2CHCl3·2CH3OH·2H2O (3), have been synthesized and characterized [LH4 = (2E,N′E)-N′-(2,3-dihydroxybenzylidene)-2-(hydroxyimino)propanehydrazide; acacH = acetylacetone; hmacacH = 2,2,6,6-tetramethyl-3,5-heptanedione; dpacacH = dibenzoylmethane]. The structural elucidation of these complexes reveals two types of DyIII centers in terms of the number of ancillary β-diketonate co-ligands coordinated to the metal centers. Detailed magnetic studies have been carried out on 1–3 which reveal a slow relaxation of magnetization at low temperatures. The relaxation of complexes 2 and 3 is distributed in three temperature ranges: lower temperature process, transition range, and higher temperature process. In the higher temperature range, the best fitting of the data for 2 yields τ0 = (6.3 ± 3.6) × 10–6 s and Ueff = (23.8 ± 4.0) K, and for 3, τ0 = (9.4 ± 5.9) × 10–6 s, Ueff = (29.0 ± 6.3) K.

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