Neutral Re (I) complexes for anion sensing

Anion sensing properties toward F− , OAc− and H2PO4 − were studied for new mononuclear and dinuclear Re(I) complexes based on a five-substituted phenanthroline moiety bearing a thiourea hydrogen-bonding receptor. Log(K 1:1) values between 4 and 6 were obtained for the complexes by UV–vis titrations and between 3 and 5 by 1H NMR titrations. The effect of hydrogen-bonding versus deprotonation of the thiourea receptor upon addition of the anions was also evaluated by UV–vis and NMR titration techniques. In addition, an X-ray structure of the Re(I) precursor complex is reported and the chirality of the mononuclear and dinuclear complexes is discussed.