ELSEVIER Surface Science386 (1997) 245-248 surface science Deposition of photo-generated mixed-valent Fe(II)-Fe(III) complexes at the surface of Langmuir monolayers Nobuo Kimizuka *, Tsutomu Asai, Shinji Ohno, Kunitaka Fujiyoshi, Toyoki Kunitake Department of Chemical Science and Technology, Faculty of Engineering, Kyushu University, Fukuoka 812, Japan Received5 November1996;acceptedfor publication 26 February 1997 Abstract A mixed-valentFe(II) Fe(III) complexwas deposited at the surface of cationic monolayersby photoirradiation of the aqueous subphase containing equimolar Fe 3÷ and Fe(CN)3- ions. The photo-depositionprocesswas detected in situ by the measurement of reflectance spectra at the air-water interface at a constant surface pressure. The present technique provides a first example of the photo-induced mineralizationprocess at the air-water interface. © 1997 ElsevierScienceB.V. Keywords." Iron; Liquid-gas interfaces; Physical adsorption; Reflectionspectroscopy;Self-assembly 1. Introduction Biomimetic fabrication of inorganic materials that are directed by organic molecular assemblies have been attracting much interest, because they provide useful approaches to control the inorganic nanostructures [1,2]. We have reported that macroscopically oriented self-supporting films were obtained by casting aqueous dispersions of a lipid bilayer membrane [3], and these multibilayer films provide two-dimensional matrices for the preparation of molecularly controlled polysiloxane networks [4], metal oxides [5], quantized cadmium sulfides [6], lead halide clusters [7] and bimetallic /~-cyano complexes [8]. In these studies, inorganic nanostructures are regulated by the two-dimen- sional space of the host multibilayer, as well as by electrostatic and van der Waals interactions acting * Correspondingauthor. Tel.: (+ 81) 92 642.3597;fax: (+ 81) 92 642.3611;e-mail: kimitcm@mbox.nc.kyushu-u.ac.jp 0039-6028/97/$17.00© 1997ElsevierScience B.V. All rights reserved. Pll S0039-6028 (9 7 ) 00322- I at bilayer surfaces. Langmuir monolayers provide another class of molecular templates which enable oriented nucleation of inorganic crystals [9], semi- conductor particles [10] and electrochemically gen- erated metal particles [11]. However, there has been no report on photo-regulation of the mono- layer-directed mineralization process. In this paper, we report a novel photo-induced deposition process of a #-cyano Fe (II)-Fe (III) mixed-valent complex at the monolayer surface. #-Cyano bime- tallic complexes are known as catalysts for water photolysis [12] and were recently highlighted as photo-responsible molecule-based magnets [13]. 2. Experimental Preparation of ammonium amphiphile 1 (see Scheme 1) has been described previously [14]. The pressure-area isotherms of the surface monolayer (rc-A curve) were measured with a computer- controlled film balance (USI system, model FSD-