Spirooxazine-based Optical Sensing of Metal Ions Using Laser Beam

The use of a He-Ne laser beam at the wavelength of 632.8 nm and with optical intensity of ∼ 1 mW/cm2 was proposed to monitor the reversible photo-chemical isomerization of a spirooxazine derivative bearing sulfobutyl substituent on the indoline part of the molecule. This laser wavelength is suitable to probe the photo-induced conversion between the conformers of the tested photochromic spirooxazine in solutions, as well as for metal ions detection through sensing the open-ring form of this compound. The usefulness of the proposed feasible method for optical sensing of metal ions, in particular, in aqueous media, was estimated.