Two 3D nonlinear optical and luminescent lanthanide-organic frameworks with multidirectional helical intersecting channels†
Abstract
Two chiral lanthanide-organic frameworks, [Ln(Hpzc)(Hida)]n (1: Ln = Eu 1a; Sm 1b; H2pzc = pyrazole-3-carboxylic acid, H3ida = iminodiacetic acid) based on rigid and flexible ligands were hydrothermally synthesized and characterized. Both compounds 1a and 1b possess unprecedented 3D 3,5-connected lanthanide-organic frameworks with intersecting multidirectional helical channels. The luminescence properties reveal that complexes 1a and 1b exhibit the characteristic emission bands of Ln3+ ions. The photoluminescence spectrum of 1a reveals characteristic line-splitting at room temperature, depending on the site-symmetry of Eu3+ ions in the complex. Second-harmonic generation (SHG) measurements reveal that 1a exhibits moderate SHG signals.