Photocontrollable Magnetism and Photoluminescence in a Binuclear Dysprosium Anthracene Complex.

By incorporating photoreactive anthracene moieties into binuclear Dy 2 O 2 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 (CH 3 CN) 2 ] ( 2 ), where HL is 4-methyl-2,6-dimethoxyphenol and dmpma is dimethylphosphonomethylanthracene. Compound 1 contains face-to-face π-π 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 .