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-nitrophenoxy)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.