Changes in the aggregation patterns of Z-2,3-diphenylpropenoic acid and its methyl ester on substituting the olefinic hydrogen with CF3 group—an FT-IR study

While in the unsubstituted Z-2,3-diphenylpropenoic acid and its methyl ester the olefinic protons rarely were part of any hydrogen bonding interaction, upon substitution by CF3 group, the possibility of (aromatic)C–H⋯F intermolecular hydrogen bond appeared and indeed realised for the molecules (E-2,3-diphenyl-3-CF3-propenoic acid and its methyl ester) in the solid state. This type of close contact was indicated experimentally by FT-IR spectroscopy.