Novel synthesis and characterisation of 3,3-dimethyl-50-(2-benzothiazolyl)- spironaphth(indoline-2,30-[3H]naphth[2,1-b] [1,4]oxazine) derivatives

Novel modified spirooxazines (SOs) with additional chelating groups were synthesised and the crystal structure of one of these was determined. UV–vis spectroscopic characterization of the photoisomerization of the SO derivatives shows that the photochromic behaviour is altered with Zn2+ coordination. In particular, addition of a group as in carboxylic acid 5 to the indole section of the SO increases the lifetime of the merocyanine Zn 2+ complex by 20-fold compared to the methylated indole 6

Chelation ability of spironaphthoxazine with metal ions in silica gel

Spironaphthoxazine (SNO) and three metal ions, Mg2+, Zn2+, and Al3+, were dispersed in silica gels by the sol-gel method. The chelation ability of SNO with the metal ions in silica gels was investigated by measuring the fluorescence spectra and was compared to that of 8-hydroxyquinoline (8-HQ) in ethanol and silica gels. A merocyanine-type isomer photoderived from SNO as well as 8-HQ easily formed complexes of the metal ions in the order of Al3+, Zn2+, and Mg2+ because the coordination ability of the metal ions to such ligands depended on their electron affinity. The changes in the fluorescence spectra of the silica gel samples during light irradiation were also investigated. The relative band intensity due to the intermediate species between the original SNO and the merocyanine species decreased and that of the complex increased with the UV irradiation time. The reverse process was observed during visible irradiation. The UV irradiation effects on the chelation of SNO and its photochromic property also depended on the electron affinity of the metal ions.ArticlePHOTOCHEMICAL & PHOTOBIOLOGICAL SCIENCES. 11(7):1164-1173 (2012)journal articl