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

Abstract

CIvHI9CIO, Mr = 274.7, triclinic, P]-, a = 11.154 (3), b = 12.685 (2), c = 12.713 (2) A, a = 100.68 (1), fl = x 113.58 (1),), = 104.50 (2) °, V = 1511.1 (6)/~3, Z = 4, Dm = 1.22, Dx = 1.215 Mg m -3, Cu Ka, A = 1.5418 A, /z = 2.16 mm 1, F(000) = 584, T = 293 K, v 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 o fl-steering ability of the chloro group is not operative in this system as there are no CI-.-C1 interactions in the crystal lattice. All five benzylidene-DL-piperitone structures so far studied are a-packed and the molecular topology appears to be a deciding factor even in the presence of steering groups.