The synthesis, crystal structures and photophysical properties of a series of cycloplatinated complexes are presented. The complexes have the general formula (C∧ N) Pt (O∧ O), where O∧ O is acetylacetonate and C∧ N represents 2-arylimidazoline ligands. All of them are luminescent in CH2Cl2 solution at room temperature. Different aryl group on N-1 of the ligand has no significant effect on the emission properties of the platinum complexes. ...