Exploring the balance between spin frustration and single-ion effects in triangular Dy3 complexes

Abstract

We report the synthesis, structures, and magnetic properties of a series of triangular Dy₃ complexes with [Dy₃(hmci)₃(MeOH)₆]·3MeOH·2MeCN·2H₂O (1) and [Dy₃(hmcb)₃(MeOH)₆]·3MeOH·1H₂O (2) (H₃hmci = 2-hydroxy-3-methoxy-5-iodobenzaldehyde hydrazone, H₃hmcb = 2-hydroxy-3-methoxy-5-bromobenzaldehyde hydrazone). These complexes adopt a calixarene-like triangular topology with phenoxide-bridged Dy³⁺ ions, leading to near-perpendicular orientation of anisotropic axes relative to the Dy₃ plane. Magnetic studies and theoretical calculations reveal rare examples of Ising spin frustration driven by dipolar interactions, while retaining a zero-field single-molecule-magnet (SMM) behavior. Furthermore, halogen substitutions at the para position of the ligands fine-tune the local crystal field environment, enabling modulation of the relaxation dynamics and slow magnetic relaxation profiles. These findings underscore the critical role of ligand design in tailoring spin frustration and optimizing the zero-field SMM performance of triangular Dy₃ complexes.