Solid-state photobehaviour and crystal packing of o-chlorobenzylidene-DL-piperitone: influence of molecular topology on photobehaviour

Abstract

C₁₇H₁₉ClO, M_r = 274.7, triclinic, PĪ, a = 11.154 (3), b = 12.685 (2), c = 12.713 (2) Å, α = 100.68 (1), β = 113.58 (1), γ = 104.50 (2)°, V = 1511.1 (6) ų, Z = 4, D_m = 1.22, D_x = 1.215 Mg m_-3, Cu Kα , λ = 1.5418 aÅ, μ = 2.16 mm^-1, F(000) = 584, T = 293 K, R = 0.057 for 3481 observed reflections. The title compound is photostable in the crystalline state and lattice-energy calculations have been employed to rationalize the photobehaviour. The well-known beta-steering ability of the chloro group is not operative in this system as there are no Cl …Cl interactions in the crystal lattice. All five benzylidene-DL-piperitone structures so far studied are alpha-packed and the molecular topology appears to be a deciding factor even in the presence of steering groups.