Microstructural and dynamical properties resulting from the hydrogen bonding interactions between ibuprofen molecules in the liquid state have been investigated by means of molecular dynamics computer simulations. Individual and collective dipole autocorrelation functions were calculated. They reveal that the behavior of the long time collective dipole correlation is dominated by the individual function due to antiparallel dipoles correlations in agreement with a value of the Kirkwood correlation factor significantly smaller than unity. The exact numeration of hydrogenbonding associating structures, their shapes cyclic or linear is a question that we have considered here. The existence of very stable small aggregates such as cyclic dimers and trimers is shown. The presence of these stable cyclic associating structures within homogeneous disordered phase are demonstrated to have a striking influence on the dynamical properties and might be at the origin of the unconventional Debye type process detected in this system. A comparison is made with the Debye-type relaxation found in microstructured monohydroxy alcohols.