Development of Molecular Recognition Reaction at the Interface and Analysis of Recognition Functions by Laser Spectroscopy

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As to molecular recognitions at the interface, hydrogen bonding receptors were synthesized and their functions were evaluated, paying attentions to recognition functions used in living systems. Reactivities and adsorption behaviors of molecules at the interface were analyzed by resonant second harmonic(RSH) spectroscopy, time resolved total internal reflection fluorescence spectroscopy(TIRF), electrochemical STM, QCM, dynamic interfacial tensiometry, and liquid droplet polarographic measurements.As a new generation of fluoroionophores based on the photoinduced electron transfer process, novel pyrene-based receptors which are donor-spacer-acceptor systems were developed. A fluorophore as an electron acceptor, pyrene, was linked to an ion receptor as an electron donor by a polymethylene chain. In these systems, a formation of an intramolecular exciplex between the excited pyrene and the ion receptor is controlled by ion complexation, resulting in the spectral responses to allow analytica … More lly useful ratiometric measurements, that is, a ratio of the exciplex emissin to the monomer emission can be used to cancel out the environmental effect. In a pyrene/thiourea system, where the thiourea group functions as an anion binding site, the maxima of the exciplex emission enhanced by anion binding were foamed to be clearly anion dependent. This dependency is another advantage of the exploitation of the exciplex emission for ion sensing. In a pyrene/amidobenzo-15-crown-5 system, where the amidobenzo-15-crown-5 group functions as an cation binding site, the fluorescence maximum of the exciplex emission was red-shifted with increasing solvent polarity, indicating the charge-transfer nature of the emission. The intensity of the emission band decreased by adding alkali metal ions. This decrease reflects the stabilities of the 1 : 1 complex.As for molecular recognitions at liquid-Liquid interfaces, complexation reactions of hydrogen-bonding reveptors with anions were examined by electrolyte ascending electrode polarography, and the facilitated aniontransfer across the interface was observed for the first time. It was found that sulfate was remarkably facilitated regardless its hydrophilic nature.As mentioned above, several ionophores were developed and examined their functions. Some of the ionophores were demonstrated to recognize anions effectively through hydrogen-bond at liwuid-liquid interfaces. Less