Modulation of magnetization dynamics of an Er(iii) coordination polymer by the conversion of a ligand to a radical using UV light

Abstract

Light-induced substance conversion is highly promising for creating new radical-based compounds. Herein, we report an Er(III) coordination polymer [Er(CA)(ACA)(DMF)(H₂O)]_n (1) and its Y(III)-diluted analogue 1@Y (H₂CA = 2,5-dichloro-3,6-dihydroxy-p-quinone, HACA = 9-anthracene carboxylic acid) with the light-induced transformation of the ligand to a radical. The χ_MT values of light-transformed products 1a and 1a@Y are higher than those of 1 and 1@Y, respectively, due to the formation of radicals by ultraviolet light irradiation, confirmed by EPR measurement as well. The effective energy barriers for magnetization reversal (U_eff) decrease from 72 K for 1 to 67 K for 1a, and from 117 K for 1@Y to 94 K for 1a@Y. This work not only provides a new light-conversion system but also reveals the nature of photo-induced variation of magnetic properties.