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Monolayers of Stober silica particles were prepared on the surface of water and deposited onto glass substrates by the Langmuir–Blodgett method. Prior to film formation the surface of the silica particles was methoxylated by washing with methanol at room temperature. The surface methoxylation was characterized by FTIR, 13C CP MAS NMR and 29Si MAS NMR investigations. Good quality hexagonally close-packed (hcp) films of silica particles were prepared from methanol dispersions of the methoxylated spherical (d=689 nm) monodisperse particles. Large (10×10 μm of size), perfectly hcp ordered domains were found in scanning electron microscopic pictures of such monolayers deposited on glass substrates. Addition of the cationic surfactant decyltrimethyl ammonium bromide (DTABr) to the spreading suspensions decreased the ordering quality. All the particle monolayers showed first and second order Bragg diffraction at the wavelengths λ=1450 and 780–790 nm, respectively. The SiO2 background light transmission decreased with loss of ordering caused by the addition of DTABr.

Several chromophores based on ferrocene, [Fe2( 5 -C5H5)2(CO)2(-CO)(-CCH3)] + and terthiophene or dithienylbenzo[c]thiophene have been synthesized. Both thienyls have been shown to act as good donor end groups in their own right but contrary to our expectations the benzo[c]thiophene merocyanine has a lower hyperpolarizablity (344 × 10 − 30 esu) than its thienyl congener (650 ×10 −30 esu). The structure of 2-[(E)-2-ferrocenylethenyl]-5-(2-thienyl)thiophene has been determined by single crystal X-ray diffraction. The terminal thienyl (thp) group is disordered over two orientations about the bithienyl C(sp 2 )C(sp 2 ) bond such that the two sulfur atoms in either thp ring are positioned trans/cis in the ratio 0.628(4):0.372(4). The integrity of the alkenyl CC remains with a bond length of 1.332(2) A and the CC lengths adjacent are 1.453(4)/1.441(4) A . Twisting of the rings from planarity occurs along the Fc–CC–(thp)–(thp) axis: the angle which the ethenylthiophene CCC4H2S moiety makes with the C5H4 is 11.2(2)°, and with the major orientation of the disordered terminal thienyl group, 16(1)°. © 2001 Elsevier Science B.V. All rights reserved.