A three-dimensional noncentrosymmetric zinc-4,4′,4′'-nitrilotribenzoate structure exhibiting second-harmonic generation responses

Abstract A coordination polymer [Zn(H-ntb)]n (1) based on the tritopic carboxylate linker of 4,4′,4′'-nitrilotribenzoate (H3-ntb) was reported here. Compound 1 crystallizes in a polar space group of Pca21 and contains two-dimensional layers formed from the left- and right-handed helical chains pillared by the benzoate moieties to give a three-dimensional structure. The present compound 1 features a noncentrosymmetric structure and displays a strong phase-matchable second-harmonic-generation (SHG) response of 1.2 times that of potassium dihydrogen phosphate (KDP). The inherent polarity of the 4,4′,4′'-nitrilotribenzoate and distortive [ZnO4] tetrahedrons as well as the asymmetric arrangement of the building blocks are responsible for the SHG activity for 1.