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Biscrown stilbene S forms complexes of 1:1 and 2:1 composition with bisammonium viologen salt V⁴⁺ in acetonitrile solution. Both of the complexes exhibit spectroscopic behavior typical of molecular electron donor−acceptor complexes. The 1:1 complex [S·V]⁴⁺ has a very high thermodynamic stability (log K = 9.08), which is due to simultaneous interaction of the two ammonium groups of V⁴⁺ with the two 18-crown-6-ether units of S. The 2:1 complex (log K = 12.28) [S·V·S]⁴⁺ likely has a sandwich-type layered structure in which the acceptor salt is located between two complexed molecules of the biscrown stilbene.

The nonlinear optical quantities, second and third harmonics (β and γ), were predicted using a quantitative structure−property relationship (QSPR) approach. Molecular orbital ab initio calculations were applied to generate easily accessible variables to be used in the partial least-squares analysis. Simplified equations are presented that could be used to predict the experimental β and γ responses, prior to further investigations of potentially interesting molecules for use in optical materials.

Self-assembled monolayer films of a metallotetraazaphthalocyanine were prepared using two different reaction conditions. The films were characterized by ellipsometry, AFM, electronic absorption spectroscopy, semiempirical MO calculations, core-level XPS, and projection of a calculated structure of the chromophore onto a surface to obtain its silhouette area for comparison with surface concentration from absorption spectroscopy. A denser packing of the chromophores is found in the SAM film prepared with bromonaphthalene at 250 °C as compared with the film from the more polar solvent DMF at 120 °C. Data is consistent with an almost vertical orientation of the chromophores in the former film. A different number of bonds connecting the chromophore with the coupling molecule is suggested as an explanation to differences in the absorption bands for the two films.

Novel microspheres from copolymers of 1,5-dioxepan-2-one (DXO) and L-lactide (L-LA) were prepared by oil-in-water solvent evaporation and oil-in-oil solvent removal. The two preparation techniques were evaluated for sphere formulation and incorporation of two different drugs. Sustained release of these therapeutic substances was obtained. The consequences of altering the DXO : LA ratio, preparation method, and drug hydrophilicity were explored and identified as factors governing sphere quality, in vitro degradation, and drug release characteristics. We show that these relationships provide a powerful means of controlling the microsphere performance. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1877–1884, 1999