Rhodamine Salicylaldehyde Hydrazone Dy(III) Complexes: Fluorescence and Magnetism

 Three new dysprosium(III) complexes [Dy 2 (HL 1 -o) 2 (L 1 )-

(NO 3 ) 3 ][Dy(NO 3 ) 5 ]·1.5ACE·0.5Et 2 O (1), [Dy(L 1 ) 3 ]·2.5MeOH·MeCN

(2), and [Dy(L 2 ) 3 ]·MeOH·MeCN (3) (HL 1 = rhodamine B

salicylaldehyde hydrazine, HL 2 = rhodamine B 3-methylsalicylaldehyde

hydrazine) were synthesized and characterized. Purple complex 1

contains two ring-open ligands HL 1 -o and shows fluorescence of the

rhodamine amide moiety, whereas yellow complexes 2 and 3 are

comprised of ring-close ligands (L 1/2 ) − and display fluorescence of the

salicylaldehyde Schiff base part. For 2 and 3, Dy(III) ions are nine

coordinated by the six oxygen and three nitrogen atoms of three chelate

(L 1/2 ) − ligands, but the arrangements of the three ligands are different

owing to the methyl substituent on HL 2 . There are three short

predominant Dy−O phenoxy bonds in 2 and 3. The largest O phenoxy −Dy−

O phenoxy angle is 148.64(17)° for 2 and 89.63(13)° for 3. Magnetic studies

reveal that complex 2 is a field-induced single-molecule magnet (U eff = 104.2 K under a dc magnetic field of 2000 Oe), and 3

exhibits only a magnetic relaxation behavior owing to the quantum tunneling of magnetization (QTM). Furthermore, ab initio