Molecular recognition is an important concept in many areas of chemistry, with enzymes as the model of perfection for catalytic efficency and specificity. A number of clever enzyme mimetic systems such as crown ethers, cyclodextrins, and calixarenes have been designed as artificial receptor sites to bind appropriate substrate molecules or ions. In this article, molecular recognition occured at the air-water interface by using surface monolayers was reviewed. Typical host molecules such as crown ether, cyclodextrin, and calixaren were modified with long alkyl chains to form surface monolayers, and they could selectively bind alkali metal ions at the air-water interface. The observed selectivity to ions corresponded well with that in bulk solutions. Specific interactions different from those in bulk solutions were observed for a diaminotriazine-functionalized monolayer which efficiently bound barbituric acids and nucleic acid bases by complementary hydrogen bonding. Chiral monolayers could recognize the chirality of guest molecule in the subphase, and also induced stereo-selective molecular recognition within the monolayer. Surface monolayers could two-dimensionally organize biopolymers (e. g., protein) and synthetic polymers in the subphase. Biotin-carrying monolayers bound specifically proteins such as streptavidin in the subphase, andconsequently produced 2D-protein crystals. These situations were visualized by means of a fluorescence microscopy technique. Polymeric amphiphiles, which contain a well-defined polymer segment as hydrophilic part, formed stable surface monolayers, and they could recognize the chain-length of guest polymers in the subphase through multiple hydrogen bonding and other interaction modes.

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Design concepts and fabrication technologies of functional membranes with molecular recognition are reviewed along with these applications to biosensors. Novel enzyme membranes have been disigned to recognize specifically their corresponding substrates and transfer electrons to electrodes through various molecular interfaces such as electron mediators and conducting polymers. These enzyme membranes are applied to fabricate new biosensors. Technology has also developed to assemble anti-body in a membrane form. Antibody membranes are applied to fabricate immunosensors.

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This paper deals with fabrications and properties of ultrathin membranes/films of conducting polymers toward molecular device and quantum functional material, which is to be considered to develop a new field of the membrane science and technology. To realize the functionalized conducting polymer membranes on this scope, the following three approaches are described; (a) functionalizations of conducting polymer membranes with functional molecules which gift a various functions to the membranes; (b) fabrications of ultrahigh anisotropic conducting polymer multilayered membrane by LB method; (c) syntheses of conducting polymer hetero-multilayers which show a quantum size effect, by a potential programmed electropolymerization method.

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The process of vision is an example of a light induced change in the properties of a bilayer membrane. As a biomimetic visual system, photoelectrochemical control of the ion-blocking ability of the Langmuir-Blodgett (LB) film was demonstrated on a gold optically semi-transparent electrode (Au OTE) coated with multilayers containing photoresponsive amphiphilic compounds. A stable monolayer was formed by spreading a chloroform solution of a photosensitive ionic amphiphilic compound on an aqueous subphase containing an ionic polymer with opposite charge. In addition to the increase in stability, the cross sectional area of the amphiphilic molecule usually increased on polyion complexation from that of the same amphiphilic molecule in the absence of the ionic polymer. Deposition of the monolayer onto the solid substrate as a very homogeneous LB film was possible. The increase in molecular area allows various photochemical reactions, which otherwise do not occur due to the steric hindrance, to proceed in the resulting LB films. A rapid decrease in emission of the polyion complexed pyrene LB films was observed upon UV irradiation in air. Application of this very sensitive quenching procedure to optical memory will be also presented as one of photochemical amplification systems.

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The present review is mainly concerned with the macromolecular organic nonlinear optical materials for frequency doubling. Organic polymer materials are expected to apply the optical devices for the transparent, easy processability and so on. Recently some studies were carring out about the polymer, chromophore and device structures. These topics are introduced in this review. One of the major problems for poled polymer systems is the lack of thermal stability after aligningchromophore units. In order to prevent the decay, some ferroelectric or crosslinkable polymers carrying chromophore moiety were prepared. They showed large d coefficients and stability. Previously, the chromophores having shorter absorption wavelength band than the harmonic wavelength have been used. However, it has made possible to apply the longer absorption wavelength chromophores by using Cherenkov type phase matching. Besides, it has reported that the novel two-directional charge transfer molecules possessed large off-diagonal, β components has shown a small decay of d ₃₃ even when the order parameter has relaxed. In optical waveguide structure, quasi phase matching accomplished by periodically poled or bleached waveguide structure was effective method to obtain harmonic light. As the practical and adroid method to achieve phase matching in waveguide, a attempt was made to adjust and suppress the phase matching condition by continuing to apply external dc voltage during frequency doubling. The guide-layer made of low T_g polymer was effective for quick response of chromophore alignment and change of refractive index against external electric field.

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In recent years, much attention has been devoted to Langmuir-Blodgett (LB) films consisting of organized molecular assemblies in the form of ultrathin layers. Concomitantly, there has been an in-creased need for establishment of characterization methods of LB film structures. Among the various analytical methods applicable to thin organic films, Fourier transform infrared (FT-IR) spectroscopy provides the most powerful tool for the analysis of constituent groups in molecules.
Recently, we proposed a new method for quantitative evaluation of-the molecular orientation by combining FT-IR reflection-absorption (RA) and transmission techniques, and applied it to the study of LB films of cadmium stearate, azobenzene-containing long-chain fatty acids and their barium salts, and polyion complexes. Here, I outline this method and results obtained for LB films of C_m H _2m-1, -φ-N=N-φ- (CH₂) _n-COOH (m=8 or 12, n=3 or 5) and their barium salts. Furthermore, I discuss about relationship between the molecular orientation evaluated by the above method and pyroelectricity in alternating (noncentrosymmetric) Y-type LB films consisting of a phenylpyrazine-containing long-chain fatty acid and perdeuterated stearic acid as well as of their barium salts. Finally, I describe new FT-IR reflection techniques such as metal overlayer attenuated total reflection (ATR) method for improving the sensitivity of spectral measurements and external reflection method for thin organic films extended on nonmetalic substrates with the absorption coefficients less than unity.

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The melting temperature (T_m) and the crystalline relaxation temperature (Tα_c) of monolayers on the water surface were evaluated by a combination of two kinds of measurements, the subphase temperature (T_sp) dependence of monolayer modulus based on the π-A isotherm and also, the T _sp dependence of the electron diffraction (ED) patterns of monolayer. T_m, and T _{α c} of monolayers on the water surface are important to decide the phase structure or molecular aggregation state in the monolayers and also, formation of a large-area defect-diminished monolayer. Monolayer prepared from fatty acid molecules with nonionic hydrophilic groups is classified into a crystalline monolayer and an amorphous one in the case of T _sp below and above T_m of the monolayer on the water surface, respectively. Formation of the crystalline or amorphous monolayers is independent of the magnitude of surface pressure. The π-A isotherm for fatty acid monolayer represents the aggregating process of isolated domains grownright after spreading a solution on the water surface. The crystalline monolayer is further classified into the two types; crystalline domains are assembled, resulting in aligning along their crystallographic axes due to an induced sintering at interfacial region among monolayer domains by surface compression at T_sp below T _{α c} and also, domains are gathered without any special orientation among domains above T _{α c}. Monolayer prepared from amphiphilic molecules with ionic hydrophilic groups is classified into a compressing-crystallized monolayer (pressure-induced crystallization) and an amorphous one at T_sp below and above T_m, respectively. In a region of very low surface pressure, even though T_sp is below T_m, spontaneous crystallization is suppressed from strong repulsion among hydrophilic groups. This indicates that a pressure-induced crystallization is induced by compressing the amphiphilic molecules on the water surface.

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