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‐propenyl­idene]‐3‐nitro­aniline, C₁₆H₁₄N₂O₃, (1a), N‐(E,2E)‐3‐(4‐methoxy­phenyl)‐2‐propenyl­idene]‐4‐nitro­aniline, C₁₆H₁₄N₂O₃, (2a), N‐{(E,2E)‐3‐4‐(di­methyl­amino)­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‐nitro­aniline, 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 optical materials.