Observing Kinetic Selectivity in Anthracene Photodimerization through Selective Quenching by Excited States of Proximate Rare Earth Cations

作者：Kevin Ruoff, Mitchell Zembower, Tyler G. Gong, Tuna Sagdan, Morgan Noody, G.S. Chen, Michael R. Gau, Alexandra M. Bacon, Cherie R. Kagan, Eric J. Schelter · 发表于：Journal of the American Chemical Society · 年份：2026 · DOI：10.1021/jacs.6c06165 · 研究领域：Lanthanide and Transition Metal Complexes、Organometallic Complex Synthesis and Catalysis、Magnetism in coordination complexes

Toward the development of new separation strategies for rare earth elements (REs; La–Lu, Y, Sc), the discovery of divergent reactivity for RE complexes is an essential first step. We report the synthesis, photophysical characterization, and photodimerization reactivity of a series of kinetically inert rare earth coordination compounds encapsulated by a 1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid (DO3A) ligand appended with a triazole-bridged anthracene arm, RE(DO3A-anthracene), 2-RE (RE = La–Pr, Sm–Lu, Y). Ultraviolet (UV) light irradiation of all 2-RE compounds produces the respective photodimers, 3-RE . The reaction kinetics are studied using UV–vis spectroscopy and are found to have no correlation with the size of the RE cation, a rare outcome in rare earth chemistry. A dichotomy is found between diamagnetic, fast-reacting congeners and paramagnetic, slow-reacting congeners, with 2-Ce, 2-Gd, and 2-Tb as notable paramagnetic, fast-reacting exceptions. We hypothesize that photodimerization can occur for this system by a singlet and/or triplet pathway, the latter of which can be suppressed by the addition of a triplet quencher (cyclooctatetraene, COT), which promotes the singlet-only pathway. The reaction rates of the singlet-only pathway correlate well with the fluorescence lifetimes of 2-RE . The findings presented here are discussed in the context of a previously reported solid-state photodimerization of a series of anthracene-based rare earth compounds, wherein di...