Résumé : A mononuclear Ru(II) complex based on a new heptacyclic ligand (dpqp) has been prepared and characterized by NMR spectroscopy, ES mass spectrometry and electrochemistry. It forms dimers and aggregates of up to seven complex units in CH3CN solution observed by ESMS. The monomer has an extremely weak luminescence in water or even in organic solvent probably due to the existence of a low lying π-π* excited state centered on the heptacycle. In spite of the strong interaction of the complex with DNA, its luminescence is not enhanced by the DNA microenvironment. © 2007 Elsevier B.V. All rights reserved.