A series of nitro-containing stilbene derivatives were synthesized by Wittig reaction of substituted benzaldehyde with nitro-benzyltriphenylphosphonium salt. It was observed that the configuration of the stilbene derivatives depended on the substituents of the substituted benzaldehyde, when the Wittig reactions were carried out in CH₂Cl₂. The main products are the E-stilbene for the substituents NMe₂, OMe, Me, Cl and H, but the Z-stilbene for the substituents CN and NO₂. Furthermore the comparison of the Z/E ratio in the reactions of three benzyltriphenylphosphonium salts with six substituted benzaldehydes was made. The results showed that the Z/E ratio of stilbene products diminished as the substituent electron withdrawing effect of group Y in the benzaldehyde decreased in the reaction of p-NO₂C₆H₄CH₂P^＋Ph₃ with YC₆H₄CHO, while the above Z/E change trend was not observed in the reactions of PhCH₂P^＋Ph₃, p-MeC₆H₄CH₂P^＋Ph₃ with YC₆H₄CHO, respectively. The molecular configuration of the target compounds was identified through the determination of their crystal structures, and their structures were also deliberately characterized by ¹H NMR, GC-MS, IR and UV-Vis techniques.

Key words: stilbene, nitro-benzyltriphenylphosphonium, substituted benzaldehyde, crystal structure, molecular configuration