Luminescent DyIII single ion magnets with same N6O3 donor atoms but different donor atom arrangements, ‘fac’-[DyIII(HLDL-ala)3]·8H2O and ‘mer’-[DyIII(HLDL-phe)3]·7H2O

Abstract

Two DyIII complexes with same N6O3 donor atoms but different donor atom arrangements ‘fac’-[DyIII(HLDL-ala)3]·8H2O (1) and ‘mer’-[DyIII(HLDL-phe)3]·7H2O (2) were synthesized, where H2LDL-ala and H2LDL-phe are tridentate NNO ligands of N-[(imidazol-4-yl)methylidene]-dl-alanine and N-[(imidazol-4-yl)methylidene]-dl-phenylalanine, respectively. Each DyIII ion is coordinated by three mono-deprotonated mono-negative NNO tridentate ligands to form a nona-coordination geometry of a tricapped trigonal prism (TTP). 1 consists of enantiomers ‘fac’-[DyIII(HLD-ala)3] and ‘fac’-[DyIII(HLL-ala)3], while 2 consists of ‘mer’-[DyIII(HLD-phe)2(HLL-phe)] and ‘mer’-[DyIII(HLD-phe)(HLL-phe)2]. The temperature dependence of the magnetic susceptibilities and field-dependence of the magnetization of two complexes showed the different magnetic profiles and the Stark splitting of the ground state 6H15/2 due to the crystal field effect on DyIII ion (4f9, J=15/2, S=5/2, L=5, gJ=4/3, 6H15/2). Luminescence spectra were observed and the fine structures assigned to the 4F9/2→6H15/2 transitions are partially observed. 1 and 2 showed an out-of-phase signal with frequency-dependence in alternating current (ac) susceptibility under a dc bias field of 1000 Oe, indicative of field induced single ion magnet (SIM). The ac magnetic susceptibilities under 1000 Oe dc field of 2 showed the maximum peaks at the higher temperature than those of 1, indicating that the energy barrier of 2 is larger than that of 1.