Linearly, circularly, or non-polarized light induced supramolecular arrangement ofdiastereomer Schiff base Ni (II), Cu (II), and Zn (II) complexes by azobenzenein PMMA matrix

摘要

Three pairs of diastereomers of Schiff base bis(N-2-hydroxy-1-isopropyl-3,5-di-bromosalicydenaminato)nickel(II), copper(II), and zinc(II) complexes and their organic/inorganic hybrid materials with azobenzene (AZ) in PMMA cast thin films have been investigated by means of polarized electronic and IR spectra and CD (circular dichroism) spectra. Due to Weigert effect for AZ, not only AZ but also metal complexes dispersed separately increased optical anisotropy after linearly polarized UV light irradiation, while supramolecular chirality after circularly polarized UV light irradiation. Besides control results by non-polarized light, optical anisotropy and supramolecular chirality were confirmed by polarized spectra (overlapped π-π* and n-π* bands and d-d bands for electronic or C=N bands for IR) and CD spectra, respectively. Degree of induced optical anisotropy mainly depends on flexibility of central metal ions (less depends on diastereomers about ligands), while degree of induced supramolecular chirality mainly depends on chilarity of ligands. In other words, optical active complexes are easy to form chiral supramolecular arrangement after circularly polarized UV light irradiation.