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We have prepared supramolecular systems of chiral Schiff base Ni(II), Cu(II), Zn(II) complexes and colloidal gold nanoparticles (AuNP) of 10 nm diameters. They demonstrated that direct adsorption of chiral Schiff base metal complex on the surface of AuNP owing to observation of clear induced CD spectra for the first time. We observed and discussed induced CD bands on AuNP from chiral Schiff base Ni(II), Cu(II), Zn(II) complexes.

In this study, we report the synthesis, characterization, and chiroptical properties of azo-group-containing chiral salen type Schiff base Ni(II), Cu(II), and Zn(II) complexes absorbed on gold nanoparticles (AuNPs) of 10 nm diameters. Induced circular dichroism (CD) around the plasmon region from the chiral species weakly adsorbed on the surface of AuNP were observed when there were appropriate dipole–dipole interactions at the initial states. Spectral changes were also observed by not only cis-trans photoisomerization of azo-groups but also changes of orientation due to Weigert effect of azo-dyes after linearly polarized UV light irradiation. Spatial features were discussed based on dipole-dipole interactions mainly within an exciton framework.

Abstract:We have here synthesized new chiral Schiff base Ni(II), Cu(II), Zn(II) complexes (Ni, Cu, Zn) and hybrid materials with azobenzene (AZ) in polymethyl methacrylate (PMMA). Linearly polarized UV light irradiation of these hybrid materials slightly increased their optical anisotropy of AZ as well as the complexes, which were measured with polarized IR and UV-Vis spectra and discussed based on TD-DFT calculations. Non-linear concentration (viscosity) dependence of PMMA solutions about artifact peaks suggested weak intermolecular interactions due to the flexibility of complexes by inserted methylene chains. Molecular modeling indicated that large spaces around complexes in PMMA resulted in easy molecular orientation (Ni > Cu > Zn) as short-term saturation of the UV light irradiation.

Abstract:The authors have prepared supramolecular systems as artificial metalloproteins composed of several chiral salen-type Mn(II) and Co(II) complexes in a HSA (human serum albumin) matrix. The docking was discussed by UV-vis spectral changes and a ligand-protein docking simulation program. After linearly polarized UV light irradiation, that anisotropy of molecular orientation of the complexes increased was confirmed by polarized IR spectra. The authors have observed that the electrochemical behavior of the aligned complexes incorporating diphenyl groups in HSA can be tuned without UV radiation damage of HSA higher structures.