Slow magnetic relaxation in a Tb(iii)-based coordination polymer

Abstract

A Tb(III)-based coordination polymer (polyTb) was synthesized by complexation of Tb(NO₃)₃·(6H₂O) and 4′,4′′′′-[1,1′-biphenyl]-4,4′-diylbis[6,6′′-bis(ethoxycarbonyl)2′:6′,2′′-terpyridine](L). The polymer structure was determined by Job's plots, DFT calculation, and X-ray absorption fine structure (XAFS) measurement. Job's plots indicated that the mole ratio (Tb ion : L) is 1 : 1. The optimized model structures suggested a La model: the LaN₆⋯(OC)₂ model. The bond distances of La–O and La–N are ∼2.80 Å and 2.60 Å, respectively. The EXAFS fitting indicated that the bond distances of Tb–O and Tb–N are 2.65 Å and 2.95 Å, respectively. polyTb shows field-induced magnetic relaxation in the solid and solution state. The luminescence of polyTb, originating from an f–f transition, was observed (ϕ = 6.9%). polyTb formed a porous structure on a Si substrate, whereas a fibrous complex structure was formed on glass. polyTb chains are orientated on glass, which were determined by XRD.