The title compounds, namely Methyl 2-methyl- 4 -phenylquinoline-3- carboxylate (I), C 18H 15NO 2, and (2E)-3-(3,4-dimethoxyphenyl)-1-(2-methyl-4 -phenylquinolin- 3-yl)prop-2-en-1-one (II), C 27H 23NO 3, comprising of the phenyl ring, exhibit differences in conformational behaviour with respect to the plane of the quinoline fragment. (I) contains the methyl ester moiety whereas (II) contains the chalcone fragment, consisting of a double bond and phenyl group containing dimethoxy groups as substituents. The dihedral angles between the phenyl group and the quinoline ring is 82.77 (7)° in (I), and 79.02 (8)° in (II) respectively. It is the weak C-H···O=C H-bond and C-H··· π interactions which dictate packing of molecules in (I). In (II), it is C-H···N and C- H··· π, involving the dimethoxy ring, which controls packing of molecules in the crystal lattice. In addition, p·· ·p aromatic stacking interactions involving the quinoline fragment is present in all the molecules. © Springer Science+Business Media, LLC 2012.