The effect of ligand design on the structural and photophysical properties of Nd(III) complexes with Schiff bases of the [(phenylimino)methyl]phenol-type

Three mononuclear Nd(III) complexes [Nd(HL1)2(NO3)3] (1, HL1=2-methoxy-6-[(E)-(phenylimino)methyl]phenol), [Nd(HL2)3(NO3)3] (2, HL2=5-methoxy-2-[(E)-(phenylimino)methyl]phenol) and [Nd(HL3)2(NO3)3]·CH3OH (3, HL3=2-methoxy-6-{(E)-[(2-methoxyphenyl)imino]methyl}phenol) were prepared in a 1:3 ratio (M:L) in methanol. The effect of the ligand substituents and their positions (meta versus para) on the electronic and photophysical properties of the complexes is demonstrated. Single-crystal X-ray diffraction studies show that HL1 and HL3 coordinate bidentate via the phenolate and methoxy oxygens, while HL2 is bound monodentately through the phenolate oxygen, with the coordination environment completed by three η2-chelated nitrates. The significant differences observed in the coordination chemistry of the three Nd(III) complexes provides the opportunity for biological application investigations.