A Practical Synthesis and X-Ray Crystal Structure of (E)-4-(1-naphthylvinyl)pyridine and Related Compounds

The synthesis, structure, and photoreactivity of (E)-4-(1-naphthylvinyl)pyridine ((E)-4-1-nvp; 1) and its coordination compounds has been investigated. Synthesis of (1) via Wittig olefination resulted in a challenging isomer separation and purification process. By synthesizing (1) via a Horner-Wadsworth-Emmons reaction, high stereoselectivity and purity was achieved. The crystal structure of (1) revealed significant intramolecular rotation facilitated by CH···pi interactions, ultimately preventing olefin stacking in both the solid-state structure of (1) and a cocrystal with a structural isomer. Novel Ag(I) and Zn(II) coordination complexes that utilize (1) as a ligand were also synthesized and fully characterized, facilitating the examination of the relationship between molecular planarity and secondary bonding contributions via Hirshfeld surface analyses. These findings deepen our understanding of intermolecular interactions involving (E)-4-1-nvp and offer insights for designing novel photoresponsive materials capable of solid-state [2+2] cycloaddition.