The relaxation dynamics of a series of molecular liquids with modified structures from aldehyde with a fixed number of carbon atoms is studied. Structural modification is made by introducing oxygen into the main chain, or by incorporating end group moieties such as ethyl, acrylate, methacrylate and dihydroxyl. Broadband dielectric measurements were performed on the glass-formers. The experimental results emphasize the importance of intermolecular interactions and molecular rigidity in determining the kinetic fragility and non-exponential parameters of the structural alpha-relaxation. (C) 2012 Elsevier B.V. All rights reserved.