Effect of doping on the photodimerization reaction and the modulation of magneto-optical properties of erbium-and neodymium-anthracene complexes
Combining photoreactive anthracene moieties with lanthanide ions,we obtained three new isostructural mononuclear compounds with the formulas Ln(SCN)2(NO3)(depma)2(4-hpy)2(Ln=Er(1Er),Nd(2Nd),Y(3Y),where depma is 9-diethylphosphonomethylanthracene,and their single molecule magnet and photodimerization behaviors were studied.All contain face-to-faceπ-π interacted anthracene groups that meet the Schmidt rule for a[4+4]pho-tocycloaddition reaction.1Er and 2Nd show characteristic near-infrared(NIR)luminescence owing to the efficient energy transfer from the ligand to the lanthanide ion,while 3Y displays excimer emission in the visible region.As a result,only 3Y underwent photocycloaddition reaction under 395 nm UV light irradiation to form[Y(SCN)2(NO3)(depma2)(4-hpy)2]n(3Y-UV).Magnetic studies revealed a field-induced slow relaxation of the magnetization at low temperatures for compounds 1Er and 2Nd,and the dominant relaxation process was the Raman process for 2Nd.After doping ErⅢ or NdⅢ into 3Y,we constructed the isomorphic samples Ln0.1Y0.9(SCN)2(NO3)(depma)2(4-hpy)2(Ln=Er(1Er@Y),Nd(2Nd@Y)).Interestingly,the diluted samples exhibited an incomplete photocycloaddition reac-tion,accompanied by changes in their luminescence colors from yellow-green to blue.Furthermore,partial photocy-cloaddition of anthracene groups in 2Nd@Y led to a slight change in the magnetic dynamics,manifested by an in-crease in the n value of the Raman process from 3.8(2Nd@Y)to 5.2(2Nd@Y-UV)which is attributed to the change in its phonon structure.CCDC:2303850,1Er;2303856,2Nd;2303854,3Y.
anthracene-based phosphonate complexlanthanide single molecule magnetphotoluminescencedoping effect
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