Molecular design, characterization, and application of multiinformation dyes (MIDs) for optical chemical sensings. 3. Application of MIDs for λ_max-tunable ion-selective optodes

By utilizing "multiinformation dyes (MIDs)", which have plural spectral change characteristics such as an absorption maximum wavelength (λ_max) shift based on a polarity change and an absorbance change due to protonation, novel λ_max-tunable ion-selective optodes were proposed and prepared by employing MIDs with membrane solvents having different polarities. For controlling the detecting λ_max of the optode, the novel polar membrane solvent [2-[[6-(2-nita)phenoxy)hexyl]oxy]methyl]isobutane-1,3-diol was designed and synthesized, which was used together with a typical membrane solvent nitrophenyl octyl ether. By mixing these two membrane solvents, the λ_max position of the optode detection wavelength can be shifted and controlled and was successfully applied to a λ_max-tunable Li⁺-selective optode based on a highly Li⁺-selective ionophore TTD14C4. The λ_max tuning technique is useful for preparing an optode system using a low-cost light source such as a light-emitting diode or a popular laser.