Tunable Nonlinear Optical Property and Photocatalytic Activity on Luminescent Chiral Lanthanide Chains

Five chiral ( P 2 1 ) isostructural lanthanide coordination complexes Ln(pic) 3 [pic=picolinic acid, Ln=La ( 1 ), Gd ( 2 ), Nd ( 3 ), Sm ( 4 ) and Eu ( 5 )] have been hydrothermally generated, featuring one dimensional right‐handed 2 1 helical chains constructed from LnN 3 O 6 of square antiprism geometry and N , O ‐chelated pic − groups, in which 3 , 4 and 5 have been reported, but we explore undiscovered properties of their own systematically. In special, 1 undergoes an abnormal transformation of symmetry as the temperature cooling to 100 K. TG‐DSC studies demonstrated that all isologues have good thermal stability with the decomposition temperature up to 400°C. Then, UV‐Vis‐NIR transmission spectroscopy measurements indicated that they possess a short‐wavelength absorption edge onset at 377 nm, corresponding to the optical band gap of 3.29 eV. Meanwhile, powder second harmonic generation (SHG) measurements revealed that the SHG intensity of 1 , 2 , 4 and 5 may be about 1.2, 2.0, 0.9 and 0.75 times that of KH 2 PO 4 , respectively. Interestingly, 1 and 3 exhibit efficient photocatalytic degradation for MB (Methylene Blue) upon UV‐light irradiation. Moreover, both 1 and 2 show strong blue luminescence.