A combinatorial chemistry approach to new materials for non-linear optics.I. Five Schiff bases

A combinatorial chemistry approach has been used to synthesize an array of Schiff bases, five of which, namely N-[(E,2E)-3-(4-methoxyphenyl)-2-propeny lidene]-3-nitro- aniline, C16H14N2O3, (1a), N-[(E,2E)-3-(4-methoxyphenyl)-2 -propenylidene]-4-nitroaniline, C16H14N2O3, (2a), N-{(E,2E)-3[4-(dimethylam ino)phenyl]-2-propenylidene}-3-nitroaniline, C17H17N3O2, (1b), N-{(E,2E)-3- [4-(dimethylamino)phenyl]-2-propenylidene}-4-nitroaniline, C17H17N3O2, (2b) , and N{(E,2E)-3-[4-(dimethylamino)phenyl]-2-propenylidene}-2- methyl-4-nit roaniline, C18H19N3O2, (3b), have been structurally characterized. A stack structure is observed for (1a) and (1b) in the crystal phase. Experimental and calculated molecular structures are discussed for these compounds which belong to a chemical class having potential applications as non-linear opt ical materials.