Structures of Three Chalcones Derived from 6-Methoxy-2-naphthaldehyde

Abstract  In the molecular structures of three new structurally related chalcone derivatives, namely (2E)-1-(2-hydroxyphenyl)-3-(6-methoxy-2-naphthyl)prop-2-en-1-one, C₂₀H₁₆O₃, I, (2E)-1-(2-chloropyridin-4-yl)-3-(6-methoxy-2-naphthyl)prop-2-en-1-one, C₁₉H₁₄ClNO₂, II, and (2E)-3-(6-methoxy-2-naphthyl)-1-pyridin-4-ylprop-2-en-1-one, III, C₁₉H₁₅NO₂, the configuration of the keto group is syn with respect to the olefinic double bond. In all three structures the molecules pack with weak intermolecular C–H···O interactions utilizing both the methoxy and keto oxygen’s in I, the methoxy oxygen in II and the keto oxygen in III. These interactions link the molecules into chains diagonally along the (011) plane of the unit cell in I and III and along the (010) plane in II. The dihedral angle between the phenyl and 2-napthyl rings in I is 31.7(3)°. In II and III the dihedral angle between the pyridyl and 2-naphthyl rings is 14.4(9)° and 1.8(9)°, respectively. C–H···O hydrogen bonding interactions influence these twist angles of these rings in I–III while weak π–π stacking interactions between naphthyl rings in I and III and also between pyridyl and naphthyl rings in II help stabilize crystal packing. [I: P2 ₁ /c, a = 7.6635(4) ?, b = 11.8047(6) ?, c = 16.7584(7) ?, β = 99.271(5)°, V = 1496.25(13) ?³; II: Pbca, a = 14.1424(4) ?, b = 6.0957(2) ?, c = 33.1458(11) ?, V = 2857.43(16) ?³; III: P2 ₁ /c, a = 11.5155(4) ?, b = 6.0020(2) ?, c = 22.4645(8) ?, β = 103.002(4)°, V = 1512.85(9) ?³]. Index Abstract  Crystal structures from three Chalcones derived from 6-methoxy-2-naphthaldehyde are reported and their geometric and packing parameters described.