Photocontrollable Magnetism and Photoluminescence in a Binuclear Dysprosium Anthracene Complex

By incorporating photoreactive anthracene moieties into binuclear Dy2O2 motifs, we obtain two new compounds with the formulas [Dy-2 (SCN)(4)(L)(2)(dmpma)(4)] (1) and [Dy-2(SCN)(4)(L)(2)(dmpma)(2) (CH3CN)(2)] (2), where HL is 4-methyl-2,6-dimethoxyphenol and dmpma is dimethylphosphonome-thylanthracene. Compound 1 contains face-to-face pi-pi interacted anthracene groups that meet the Schmidt rule for a [4 + 4] photocycloaddition reaction, while stacking of the anthracene groups in compound 2 does not meet the Schmidt rule. Compound 1 undergoes a reversible single-crystal-to-single-crystal structural transformation upon UV-light irradiation and thermal annealing, forming a one-dimensional coordination polymer of [Dy-2(SCN)(4)(L)(2)(dmpma)(2) (dmpma(2))](n) (1UV). The process is concomitant with changes in the magnetic dynamics and photoluminescent properties. The spin-reversal energy barrier is significantly increased from 1 (55.9 K) to 1UV (116 K), and the emission color is changed from bright yellow for 1 to weak blue for 1UV. This is the first binuclear lanthanide complex that exhibits synergistic photocontrollable magnetic dynamics and photoluminescence. Ab initio calculations are conducted to understand the magnetostructural relationships of compounds 1, 1UV, and 2.

Automated summary

In this study, two new compounds with unique structures and properties were synthesized by incorporating photoreactive anthracene moieties into binuclear metal motifs. One of the compounds undergoes a reversible structural transformation under light and heat treatment, accompanied by changes in magnetic dynamics and photoluminescent properties. This is the first binuclear metal complex that exhibits photocontrollable magnetic dynamics and photoluminescence.