Crystal structure of 1-{(Z)-[(2E)-3-(4-chloro­phen­yl)-1-phenyl­prop-2-en-1-yl­idene]amino}-3-ethyl­thio­urea

In the title thio­semicarbazone compound, C(18)H(18)ClN(3)S, the CN(3)S residue is almost planar (r.m.s. deviation = 0.0031 Å) and forms dihedral angles of 65.99 (7) and 34.60 (10)° with the phenyl and chloro­benzene rings, respectively; the dihedral angle between the aromatic rings is 85.13 (8)°. The conformation about the C=N bond is Z, and that about the C=C bonds is E. The imine N and ethyl N atoms are syn and are linked by an eth­yl–imine N—H⋯N hydrogen bond. This H atom also forms an inter­molecular hydrogen bond to the thione S atom, resulting in a supra­molecular helical chain propagating along the b axis. The chains are consolidated into a three-dimensional architecture by phenyl-C—H⋯Cl contacts and weak π–π inter­actions between centrosymmetrically related chloro­benzene rings [inter-centroid distance = 3.9127 (15) Å].