来源：ACS Publications
Facilitating different chemistries between the rare earth (RE = La–Lu, Sc, Y) ions is of significant interest for their separations. While the bulk of attention has been on maximizing the small differences in their ground state chemistry, interest is beginning to shift toward the differences in their electronic excited states. In this work, we demonstrate modulation of the photostationary state of an azobenzene derivative, Na1, via chelation to a series of REIIIDO3A (DO3A = 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid) complexes. The extent of photoisomerization of 1– follows the trend in REIII Lewis acidity with two exceptions: SmIII and ErIII. UV–vis spectroscopy, titration experiments, and computational analysis show that these exceptions are a result of energy transfer rather than differences in ground state chemistry. These results open a pathway to differentiate REs by new photochemical means.
In this work, we study the photophysical properties of a chelating azobenzene derivative upon coordination to REIII complexes: [REIII(DO3A)-1]−. We demonstrate a Lewis acidity trend in the extent of isomerization at the optimized photostationary state (PSS). Importantly, a break in this trend is observed for RE = Sm or Er, which reach much lower Z/E ratios at the PSS than would be expected based on Lewis acidity. This is attributed to energy transfer from excited ligand 1 to SmIII and ErIII excited states, quenching photoisomerization (Figure 1c). These results are an important finding toward generating single ion-selective reactivity among a series of REs that disrupts typical trends in the chemistry of these metals, toward a new basis for selective RE separations.