Structures of (2E,5E)-2-(4-cyanobenzylidene)-5-(4-dimethylaminobenzylidene)cyclopentanone and (2E,5E)-2-benzylidene-5-cinnamylidenecyclopentanone

Abstract The X-ray crystal structures of ( 2E,5E )-2-(4-cyanobenzylidene)-5-(4-dimethylaminobenzylidene)cyclopentanone ( I ) and ( 2E,5E )-2-benzylidene-5-cinnamylidenecyclopentanone ( II ) are presented, compared to the gas phase structures calculated using density functional theory, and discussed in the context of the photophysical behavior exhibited by I and II . Compound I crystallizes in the triclinic space group P 1 ¯ with a  = 6.8743(2) A, b  = 8.8115(2) A, c  = 14.9664(4) A, α  = 77.135(2)°, β  = 81.351(2)°, γ  = 80.975(2)°, and Z = 2, and exhibits a planar structure. Compound II crystallizes in the monoclinic space group C 2/ c with a  = 33.4281(10) A, b  = 11.9668(4) A, c  = 7.8031(2) A, β  = 92.785(2)°, and Z  = 8, and adopts a nonplanar structure in the solid state and calculated structure.