We report the use of 3,3-bis(2-imidazolyl) propionic acid (bip-OH, 1) as a new chelating bis(imidazole) ligand. The synthesis and full characterization of complexes Re(bip-O)(CO) 3 2 and [Ru(bpy) 2 (bip-OH)] 2+ 3 is reported. Both complexes show interesting spectroscopic properties, namely IR for compound 2 and 1 H NMR for 3, respectively. The free carboxylic acid functionality of 1 may be used for the coupling to biomolecules. We have prepared two peptide nucleic acid (PNA) decamers to which the rhenium complex 2 is coupled. All reactions were carried out by solid phase synthesis methods. The Re–PNA oligomer conjugates Re(CO) 3 (bip– tgt cta gca a –NH 2 ) 4 and Re(CO) 3 (bip– agg agc aac t-Lys–NH 2 ) 5 were obtained in good yield and high purity after HPLC purification and identified by their mass spectra. The interaction of 5 with complementary DNA yields a melting temperature of (53.9±1) °C. This is the first DNA melting temperature reported for an organometallic metal–PNA conjugate.