Mapping the spatial arrangement of chemical functional groups and their interactions is of significant importance to problems ranging from lubrication and adhesion to recognition in biological systems. A force microscope has been used to measure the adhesive and friction forces between molecularly modified probe tips and organic monolayers terminating in a lithographically defined pattern of distinct functional groups. The adhesive interactions between simple CH(3)/CH(3), CH(3)/COOH, and COOH/COOH functional groups correlate directly with friction images of sample surfaces patterned with these groups. Thus, by monitoring the friction between a specifically functionalized tip and sample, one can produce friction images that display predictable contrast and correspond to the spatial distribution of functional groups on the sample surface. Applications of this chemically sensitive imaging technique are discussed.

as a synthetic intermediate in the production of indenyllanthanide and -actinide complexes. It has appreciable solubility in aromatic hydrocarbons; Sm(C9H7)3,23 U(C9H7)3C1,25 and Sc(C9H7)326 were all initially prepared from toluene solutions of Mg(C9H7)2 mixed with the anhydrous metal chloride.

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A series of novel poly(2,5-dialkoxy-p-phenyleneethynylene)s (PPEs) has been prepared by the palladium-catalyzed cross-coupling polycondensaton of aryl acetylenes and aryl iodides. Different alkoxy side chains including n-hexadecyloxy, n-octyloxy, (2-ethylhexyl)oxy, (2-methylpropyl)oxy, (3-(dimethylamino)propyl)oxy, and (7-carboxyheptyl)oxy groups were attached to the rigid-rod polymer main chain. With this structural concept, polymers having an identical conjugated backbone but different supramolecular structures in the solid state could be achieved. X-ray diffraction measurements on thin films show that the polymers which have sterically hindered side chains are essentially disordered, while those with only linear side chains can form lamellar structures with significant degrees of long-range order. High photoluminescence (PL) quantum yields, up to 0.86 in solution and 0.36 in the solid state, have been measured for the new materials. While the solution quantum yields are independent of the functionalization, solid-state quantum efficiencies were found to be related to the degree of long-range order in the samples, decreasing with increasing order. The coplanar orientation of the conjugated polymer backbones is assumed to lead to the formation of excimer complexes which provide nonemissive decay channels for the excited states. These nonemissive orientations are more significant in the materials having a greater degree of long-range order.

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