Lanthanide-acetate-phthalate coordination polymers: Energy transfer, white light emission and colorimetric titration

Abstract

Motivated by the use of mixed sensitizers and photophysical properties of lanthanide coordination polymers, a new series of homometallic [LnIII(phth)(OAc)(H2O)] frameworks (LnIII = NdIII (I), SmIII (II), EuIII (III), GdIII (IV) and TbIII (V), H2phth = phthalic acid, HOAc = acetic acid) as well as three series of heterometallic [Tb1-xEux(phth)(OAc)(H2O)], [Tb1-yNdy(phth)(OAc)(H2O)] and [Eu1-zNdz(phth)(OAc)(H2O)] were synthesized and characterized. Single crystal structures of the homometallic frameworks were elucidated. The isostructure of all the synthesized frameworks was ensured and their solid-state photoluminescent and colorimetric properties were examined from which the sensitizing ability of phth2− and OAc-, their triplet state energies and substantial influence of non-radiative relaxation in III were revealed and discussed. Based on both spectroscopic and colorimetric perspectives, the inter-lanthanide energy transfers (TbIII-to-EuIII, TbIII-to-NdIII and EuIII-to-NdIII) and colorimetric titration in the heterometallic frameworks were investigated. The results are presented and discussed. In addition, potential of II (SmIII) as a stable, single-component white light luminophore was demonstrated.