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The chemical modification of polydiacetylenes is discussed as an approach to the modification of the electronic structure of this novel class of crystallographically ordered conjugated polymers. Single crystals of poly-1,6-di-N-carbazolyl-2,4-hexadiyne react with either NO2+BF4- or fuming HNO3 (gas or liquid) to introduce nitro groups in the 3 and 6 positions of carbazole rings. These reactions do not result in highly conductive materials. Poly-DCH crystals are inert to NOCl and concentrated HNO3 under conditions described herein.

The term "design" of a solid state polymerization, taken to imply the necessary crystallographic and mechanistic considerations, is introduced with a view toward discovery and development of new lattice controlled processes. Using examples from known solid state polymerizations, a qualitative discussion of several crystallographic and mechanistic issues is presented. With the caveat that such issues may not be easily separated, a central conclusion appears to be that mechanistic problems associated with initiation and propagation steps may hold the key to progress in this area. While chlorine, aqua regia, and nitric acid convert single crystals of poly-1, 6-di-N-carbazolyl-2, 4-hexadiyne (DCH) to amorphous solids, bromination, which proceeds more rapidly as temperature is lowered, results in a crystalline solid. These reactions are anisotropic and their products are characterized by spectroscopic and crystallographic techniques. It is concluded that the initial reactivity is controlled by carbazole energy levels, rather than those of the conjugated backbone.

X-ray rotation photographs of brominated poly-1, 6-di-N-carbazolyl 2, 4-hexadiyne (DCH) reveal a chain axis repeat distance indicative of the preservation of a polydiacetylene (PDA) structure. Weissenberg photographs of a partially reacted poly-DCH crystal display evidence of the formation of a new crystalline phase. Electron microscopy of chemically modified poly-DCH reveals preservation of a fibrous morphology. The modified polymers do not appear sensitive to electron beam radiation during image formation. The reaction of poly-DCH with bromine has been monitored by electron spin resonance spectroscopy. The g-value increases significantly in the course of the bromination. Static susceptibility measurements of poly-DCH and other PDAs reveal that they are primarily diamagnetic materials.

With an eye toward a study of crystalline monoacetylene solid state reactivity as an approach to crystallographically ordered polyacetylenes, the crystallographic and absorption and emission spectral characteristics of 10-undecynamide and the cyclohexylurethanes of 5-hexyn-1-o1 and 10-undecyn-1-o1 have been studied at ambient temperature. Spectral studies at short wavelengths were performed using vacuum ultraviolet radiation from the National Synchrotron Light Source. The compounds investigated are not thermally reactive at temperatures below their melting points and are effectively inert to 60Co gamma radiation at room temperature. The crystal structures of 10-undecynamide and the cyclohexylurethane of 5-hexyn-1-o1 have been solved, and both reveal contacts shorter than 3.70 Å between acetylenic carbon atoms. For 10-undecynamide, excitation at all wavelengths between 120 and 300 nm leads to emission at wavelengths greater than 300 nm.