2-Cyano-5-({4-[N-methyl-N-(2-hy­droxy­eth­yl)amino] phen­yl}diazen­yl)pyridine

In the title compound, C(15)H(15)N(5)O, the benzene and pyridine rings make a dihedral angle of 30.86 (7)°. In the crystal, chains of mol­ecules are wrapped around the screw axes into compressed helices, through hydrogen bonding between the hy­droxy and cyano groups. The chains are linked by weak C—H⋯N and C—H⋯O inter­actions. The π conjugated unit of the mol­ecule is almost perpendicular to the helix axis, and the formation of the helix is allowed by a gauche-type torsion angle in the hy­droxy­ethyl tail. In this way, consecutive chromophore units along the chain are placed in a strict anti­parallel arrangement, and this is energetically favoured because of the high dipole moment of the mol­ecule.