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ABSTRACT: Mixed LB films of the CT complex of TMB * TCNQ and stearic acid (SA) were prepared. The structures, molecular orientation and morphology of the mixed LB films were characterized by IR, UV-Vis-NIR, XRD and AFM. Our results show that TMB * TCNQ could be deposited on solid substrates by mixing with SA. The complex is mixed-stack, and the degree of charge transfer is 0.35. The chromophore planes of both TCNQ and TMB are perpendicular to the substrate surface and the hydrocarbon chain of SA is inclined at an angle with respect to the substrate surface. There are two kinds of diffraction bands in the XRD spectra, and they probably arise from SA and TMB * TCNQ, respectively. The morphology of mono- and multilayer mixed LB films with molar ratio 1 : 1 consists of many nanorods and particles, and the amount of nanorods and particles increase with increasing the number of monolayers.
Guang pu xue yu guang pu fen xi = Guang pu 06/2008; 28(5):1140-4. · 0.84 Impact Factor
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ABSTRACT: Control of crystal polymorph and size is very important in many application fields. Herein we demonstrate that Langmuir–Blodgett (LB) films of stearic acid (SA) and octadecylamine (ODA) can serve as templates and generate different polymorphs of glycine crystals. In the neutral aqueous solutions, γ-glycine crystallizes on LB films of ODA while the polymorphic outcome becomes the α-form on LB films of SA. These observed results could be explained by the electrostatic interactions and geometric lattice matching at the LB film/crystal interfaces, respectively. By keeping the appropriate supersaturation, we have successfully controlled the number of crystals grown on LB films; for example, in some certain cases, only one piece of crystal was grown on LB films in solution. Therefore, large crystals of centimeter size could be prepared. These experimental results suggest a new approach to produce an organic crystal with bulk scale.
11/2007;
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ABSTRACT: Herein we report a new method to collect a qualified infrared spectrum of a solute in solution by two solvent cells with different thickness during background single-beam spectrum scanning. By collecting the background spectrum with two cells (two stages), we successfully achieved accurate solvent compensation between a sample and a reference, namely, the solvent amounts in the sample and background measurements could become congruent. Therefore, the solvent bands were thoroughly suppressed in the infrared spectrum and a qualified spectrum of the solute was obtained.
Analytical Sciences 08/2007; 23(7):869-70. · 1.25 Impact Factor
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ABSTRACT: Oriented crystallization of CuSO4·5H2O on a Langmuir–Blodgett (LB) film of stearic acid has been studied in the temperature ranges of 73–68 °C and 53–20 °C, respectively. This is the first time that the LB film at temperature above its melting point has been served as a template to induce nucleation and growth of crystals. The experimental results demonstrated that the LB film in the liquid state has the ability of directing the nucleation and growth of crystals. Moreover, X-ray diffraction patterns of the as-prepared crystals revealed that the orientation of the attached crystals on the LB film is affected by temperature greatly. The (1¯ 2 2) peak is very strong in crystals grown at higher temperature but absent at lower temperature. These results implied that structural changes in the LB film tuned by temperature determine the orientation of the attached crystals. The morphologies of the crystals showed that the orientation changes of the attached crystals influence the shapes and colors of CuSO4·5H2O crystals strongly.
Journal of Crystal Growth 310(22):4652-4655. · 1.73 Impact Factor
